{"paper_id":"1e5bc8b2-1eb0-41d0-bef9-3b74fe408a32","body_text":"Crossing the divide: Use of health services during the handover period from child and adolescent to adult mental health services, 2008-2021. A Norwegian National register study. | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Crossing the divide: Use of health services during the handover period from child and adolescent to adult mental health services, 2008-2021. A Norwegian National register study. Sara Lyster, Ottar Bjerkeset, Johan Håkon Bjørngaard, Sara Marie Nilsen, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8133858/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Adolescence and early adulthood represent periods of heightened vulnerability to mental health disorders. In Norway, mental health care shifts from child and adolescent mental health services to adult mental health services at age 18, which may result in fragmented transitions and treatment discontinuity. The aim of this study was to examine health service use and patterns between ages 15 and 21, with particular attention to the transition in specialist mental health services that typically occur around age 18. Methods We conducted a population-wide registry study including all Norwegians aged 15–21 between 2008 and 2021 (n = 1,313,077). Health service utilization was analyzed using Poisson regression. Subgroup analyses included individuals with established mental health needs, namely all adolescents with a GP-recorded mental health diagnosis (n = 372,109) and those with child and adolescent mental health service contact at age 17 (n = 71, 779). Results Specialist mental health service use peaked at age 16, declined sharply after 18, and reached its lowest levels around 20. In contrast, GP and out-of-hours GP consultations increased steadily, particularly after age 18, while somatic and acute somatic services remained stable. The same pattern appeared in both subgroup analyses, of youth with a GP-recorded mental health diagnosis and in those with recent contact with child and adolescent mental health services at age 17. Conclusion Specialist mental health service use declines sharply after the transition to adult care, while GP reliance increases. These findings suggest structural rather than clinical causes, highlighting the need for better continuity across the change in mental health service levels. Mental Health Services Child and Adolescent Mental Health Adults Mental Health Transition of care Health Service Utilization Background The prevalence of psychological distress and mental disorders in adolescents and young adults is steadily increasing, along with their overall impact on individuals and society ( 1 ). This is a developmental period marked by vulnerability for onset of mental health disorders ( 2 , 3 ). Adolescents typically receive care from children and adolescent mental health services and transition to adult mental health services around age 18. This handover is frequently characterized by fragmentation and discontinuity, leading to drop-out or delays in care ( 4 ). General practitioners (GPs), including out-of-hours services, often serve as the first point of contact, yet may lack the resources to manage complex mental health needs ( 5 – 7 ). Somatic health services may also be involved, particularly when mental health issues present physical symptoms or self-harm, but integration with psychiatric services remains limited. While the appropriate level of service use is not well established, challenges in coordination are likely to affect continuity of care during this critical window. Adolescence is also a period of critical life transitions such as completing high school, entering higher education or employment, moving out of the family home, and developing autonomy ( 8 – 11 ). For adolescents facing mental health challenges, the combination of increased responsibilities and service disruptions can be particularly difficult. These challenges have been associated with adverse outcomes, including educational disruption, difficulties entering the workforce, reduced social independence, and increased contact with the criminal justice system ( 8 , 12 , 13 ). In many countries, the separation between child and adolescent and adult mental health services at age 18 poses a barrier to continued care ( 14 ). Entry into adult services often requires meeting more stringent criteria, including symptom severity thresholds, co-payment, and regular attendance ( 9 , 15 , 16 ). Research from different health care systems shows that this transition is often poorly coordinated, with limited joint planning, differing eligibility criteria, and cultural differences between the services. These issues may stem from the two services having different models of care: child and adolescent care typically offers holistic support and addresses a broader spectrum of less severe difficulties, while adult services focus on treating more severe psychiatric disorders within a biomedical framework ( 10 , 17 , 18 ). The abrupt shift in services combined with broader developmental challenges often reduces engagement during this period. Financial barriers may further contribute, where young people are required to pay user fees for GP visits from age 16, while co-payments for specialist mental health services apply from age of 18 in Norway. Some young people disengage even before transition age, particularly those with milder symptoms or inconsistent attendance, resulting in further gaps in care ( 19 , 20 ). Poorly coordinated handovers and limited treatment options exacerbate discontinuity and can significantly affect service users, caregivers, and the capacity of mental health services to deliver high-quality care ( 6 , 21 – 23 ) The aim of this study is to investigate patterns of health service use between ages 15 and 21, covering the period in which many adolescents transition from child and adolescent to adult mental health services. Methods Setting Norway provides universal healthcare with equal access across two administrative levels. Specialist care, including hospitals and mental health services, is managed by regional health authorities, while municipalities oversee primary care such as GPs and social services. National health registries cover the entire population and include information on service type, frequency, and diagnoses in child and adolescent mental health care ( 24 ). Child and adolescent mental health services provide specialized care for individuals under 18, with some flexibility up to 21. Referrals typically come from GPs, school health services, or child welfare services. Services include outpatient clinics, day treatment, and inpatient units, mainly within public hospitals. At age 18, patients are eligible for adult mental health services, which are regulated by the Mental Health Care Act and the Specialist Health Services Act. Until now, user fees have applied from age 18, but from 2025 services will be free up to age 27. Contract specialists, typically psychologists, in own practices, are also engaged through government contracts to provide outpatient services. Coordination remains challenging due to separate laws and administrative structures for child and adult services. From birth, all individuals are entitled to a named regular GP, facilitating continuous care, including mental health support and coordination across services ( 25 , 26 ). Both regular GP consultations and out-of-hours GP services are available, with the latter operating 24/7. Co-payments for both types of GP services are introduced at age 16. Somatic healthcare includes hospital admissions, outpatient contacts and surgeries, while acute somatic care provides 24-hour emergency access. Data sources and variables Using a de-identified unique linkage key, based on the personal ID number, we linked data across national health and administrative registers. We used data from the Norwegian Patient Registry, which contains specialist care data, and the Control and Payment of Health Reimbursement (KUHR) database, which records primary care activity, including mental health diagnoses, coded as P-codes in the ICPC-2 system ( 27 ). Background demographic data was available from Statistics Norway. Statistics Norway provided demographic and educational data for individuals and parents. KUHR included information on GP affiliation and out-of-hours GP use. The Norwegian Patient Registry contained ICD-10 diagnoses, specialist mental health contacts, and hospital admissions. Study population The study included 1,313,077 individuals aged 15–21 between 2008 and 2021. Subgroup analyses examined individuals with a P diagnosis (N = 372,109) in GP records. They also included individuals with at least one contact in child and adolescent mental health services aged 17 (N = 71, 779), representing those potentially eligible for continued specialist care. Covariates Covariates included age, sex, immigration status, educational attainment, parental education, and calendar year. Foreign born were defined as foreign-born individuals with two foreign-born parents and four foreign-born grandparents. Norwegian born were therefore individuals born in Norway. Parental education grouped as low parental education included primary, lower secondary, upper secondary and short post-secondary education. High parental education was presented as bachelor’s level and beyond to indicate socioeconomic status. The individuals’ educational attainments were grouped as high or low, where their last reported educational achievement was used. Low educational attainment was grouped as finished upper secondary/high school, while high educational attainment was grouped as finished any education above secondary/high school level. ICPC-2- P- diagnosis (P-diagnosis), as an indicator of psychological symptoms, status was defined as “ever” versus “never”. Calendar year was included to control temporal trends. Statistical analysis Analyses were conducted with STATA/MP 18.0. Using a panel data longitudinal dataset, we analyzed the number of contacts with child and adolescent mental health care, adult mental healthcare, GP, out-of-hours GP, somatic care and acute somatic care using panel data methods to be able to observe individuals at multiple times over years to control for unobservable heterogeneity and estimate effects more precisely. We used Poisson regression, with standard errors clustered at the individual level to account for correlated observations. We adjusted for variations between the calendar years with dummy variables for each year of follow-up, and for sex. The study also presents descriptive statistics for the whole population health care use showing mean, standard deviation, minimum and maximum contacts within each health care service. Subgroup analyses To assess continuity of care among those with established mental health needs, we conducted two subgroup analyses. First, we examined individuals with at least one P-diagnosis recorded in GP or out-of-hours GP services (N = 372,108). Second, we analyzed those with contact with child and adolescent mental health services at age 17 (N = 71,779), representing patients who in principle could require continued follow-up in adult services. These subgroups allowed us to evaluate whether observed age-related changes reflected the general population only, or also those with documented or ongoing specialist care needs. Results Descriptive statistics Table 1 shows that, on average, individuals had 1.55 contacts with a general practitioner (GP) per year, making this the most frequently used service. Contacts with specialist mental health services were less common (mean = 0.54), followed by somatic and acute somatic services (mean = 0.51) and out-of-hours GP services (mean = 0.27) (Table 1). The mean number of contacts associated with a mental diagnosis was 0.25 per person per year, indicating that a relatively small proportion of total healthcare use involved a recorded mental health diagnosis. Table 1 revealed distinct age-related patterns across service types. The mean number of contacts with specialist mental health services declined with age, from 0.66 at age 15 to 0.40 at age 21. In contrast, contacts with GP increased steadily, from a mean of 1.20 at age 15 to 1.75 at age 21, while out-of-hours GP contacts rose from 0.20 to 0.31 over the same period. The mean number of contacts for somatic and acute somatic care remained relatively stable, ranging from 0.51 at age 15 to 0.55 at age 21. Additionally, GP and out-of-hours GP contacts involving a psychiatric diagnosis increased with age, from 0.19 at age 15 to 0.33 at age 21. Primary analysis - Health care service utilization Use of GP services increased steadily with age, from a relative ratio (RR) at 0.92 for the age of 16 (95%CI 0.92–0.92) to a RR of 1.21 at age 19 (95%CI 1.21–1.22) and remained stable through age 21 compared with the age of 15 (table 2). The same pattern was visible in the use of out-of-hours GP services, a sharp increase during late adolescence, with a RR = 0.80 at age 16 (95%CI 0.79–0.80) and peaking at the age of 19 = 1.28 (95%CI 1.27–1.28) relative to the age of 15. Indicating a growing reliance on primary care as adolescents transition into adulthood. The out-of-hour GP use declined slightly to a RR = 1.07 by age 21 (95%CI 1.06–1.08) compared to the reference age, suggesting that acute help-seeking outside regular hours becomes more frequent toward the end of adolescence but stabilizes thereafter. Specialist mental health services were most frequently used in mid-adolescence, with a RR = 1.23 at age 16 (95%CI 1.22–1.24) and 1.31 at age 18 (95%CI 1.30–1.33) compared to the 15-year-olds. However, use declined notably after age 18, reaching RR = 0.72 at age 19 (95%CI 0.71–0.73) and remaining below the reference level at older ages, until 21. This indicates a substantial drop in specialist mental health service engagement in early adulthood. For acute somatic services, use remained relatively stable but with minor fluctuations. RRs ranged from 0.89 at age 16 (95%CI 0.87–0.90) to 1.10 at age 21 (95%CI 1.08–1.11) relative to the age of 15, suggesting a small increase in physical health service utilization with age. Subgroup analysis 1 - Health Care Utilization for the ones with P-diagnosis Sub-analyses (Graph 3, Table 3) revealed the use of general practitioner and out-of-hours GP services remained relatively stable across ages for adolescents with a p diagnosis, with a slightly higher use of GP = 1.14 (95% CI 1.14-1-15) and out-of-hours GP at 19 at 1.22 (95% CI 1.21–1.23) relative to the 15 year olds within the same group. Those with a P-diagnosis had the highest use of specialist mental health services at age 18 RR 1.31 (95%CI 1.30–1.32), with a drop to 0.73 (95% CI 0.72–0.73) within the age of 19 relative to the age of 15. The RR rose steadily to 1.10 by the age 21 (95% CI 1.09–1.12). The use of specialist mental health services for this group declined after the age of 18, with an RR of 1.23 at the age of 16 (95% CI 1.22–1.24) and to 0.87 by the end of age 18 (95% CI 0.86–0.88) compared to the age of 15. Among individuals without a P-diagnosis, there was a gradual increase in GP use with age (table 3, graph 3), where the RR was 0.91 (95% CI 0.90–0.91) at age 16 and peaked at 1.29 (95% CI 1.29–1.29) at age 19, relative to age 15. GP use stabilized by age 21 with an RR of 1.04 (95% CI 1.04–1.05). For out-of-hours GP consultations, use increased from RR 0.80 (95% CI 0.79–0.80) at age 16 to RR 1.33 (95% CI 1.32–1.34) at age 19, before stabilizing around RR 1.06 (95% CI 1.05–1.07) by age 21. In contrast, specialist mental health service use declined markedly after mid-adolescence, with RR 1.23 (95% CI 1.20–1.26) at age 16, peaking at RR 1.47 (95% CI 1.42–1.53) at age 18 relative to the age of 15. The use of out-of-hour GP dropped to a RR of 1.08 (95% CI 1.00-1.16) by age 21, with the lowest use observed at age 20 (RR 0.57, 95% CI 0.54–0.61) compared to 15. Acute somatic and somatic service utilization remained relatively stable across ages, showing only minor increases from RR 1.06 (95% CI 1.05–1.07) at age 16 to RR 1.08 (95% CI 1.07–1.09) at age 21, suggesting consistent use of somatic and emergency care throughout late adolescence and early adulthood. Subgroup analysis 2 - Mental health utilization for the population with one or more contacts in child and adolescent mental health services the year they turned 17 Sub-analysis within the population with one or more contacts in child and adolescent mental health services the year they turned 17 (Table 5, graph 5) showed smaller to no increases in GP use with a RR at 0.96 (95% CI 0.96–0.97) at age 16 and RR of 1.04 at age 18 (95% CI 1.04–1.05) compared to the age of 15. The use of out-of-hours GP services had a higher rise, whereas at 16 the RR was 0.85 (95% CI 0.83–0.86) and 1.11 at the age of 18 (95% CI 1.1–1.15) relative to the age of 15. Regardless of gender, parental education, education, immigration background, or diagnostic status, there was a marked reduction in specialist mental health utilization beginning at age 18, with RR dropping steadily to their lowest levels around age 20 (Table 5). The overall RR for the use of specialist mental health services for this population (table 6 and graph 5) declined from 1.58 (95% CI 1.56–1.59) at age 18 to 0.74 (95% CI 0.73–0.76) by age 21 compared to 15. Utilization of acute somatic and somatic services remained stable across the age span with modest fluctuation in RR. The findings for this subgroup were interpreted cautiously due to potential regression to the mean. Discussion Main findings The main findings from this study of 1.3 million Norwegian adolescents and young adults showed a marked decrease in specialist mental health service use, accompanied by an increase in consultations with GPs and out-of-hours GP services after age 18, coinciding with the crossing from child and adolescent to adult mental health services. The reduction in use of specialist mental health services was also evident in subgroup analyses of individuals with a mental health diagnosis set by a GP and those with contact with child and adolescent services at age 17. Health Service utilization in adolescents and young adult population Results from the Norwegian Young HUNT study show a marked rise in adolescent anxiety and depression symptom level over the past two decades ( 28 ). Against this backdrop, our results revealed a decline in specialist service use and a simultaneous increase in GP and out-of-hours GP consultations after age 18, despite continued or growing mental health needs in this age group. This shift reflects both a shortfall in adult mental health capacity and the structural handover at age 18, when many adolescents are discharged from child services without coordinated transfer to adult care ( 19 , 29 ). GP consultations increasingly involve psychosocial issues and conversation therapy ( 30 ), but concerns remain about whether primary care has sufficient resources and expertise to manage complex mental health conditions ( 31 ). As young people age out of children’s mental health services, many find themselves with limited alternatives, particularly in regions where adults mental health capacity is stretched or thresholds for acceptance are high ( 18 ). Financial factors also play a role. In Norway, co-payments begin at age 16 for GP visits and at 18 for specialist mental health services, with specialist care substantially more expensive. The observed rise in GP use may therefore reflect both gaps in specialist availability and relative affordability, as child services often discharge young adults to their GP after 18 ( 32 ). Earlier studies found reduced GP use after the introduction of co-payments, suggesting that the increase we observe represents a structural shift in service provision rather than a decline in need ( 33 ). Norway is however subsidized, having an annual user fee of maximum NOK 3278, where one visit to the GP is approximately NOK 240 and a visit to the specialist mental health services after the age of 18 is maximum NOK 386. Despite this reliance on GPs, barriers to care remain high. Young people are less likely than adults to seek professional help for conditions such as depression ( 34 , 35 ). Stigma, confidentiality concerns, reliance on informal support, and difficulties navigating the health system are common obstacle ( 36 – 38 ). Barriers are especially pronounced among males and those from minority or indigenous backgrounds ( 39 ). Even adolescents with high symptom levels may disengage, particularly when faced with the new responsibility of scheduling appointments, renewing prescriptions, and adherent to treatment. Disengagement at this vulnerable stage increases risks of symptom worsening, unemployment, and long-term social exclusion, as well as a lack of trust to the health care system, motivation and hope for the future ( 17 , 40 , 41 ). Legal autonomy in health matters from age 16 may also leave some adolescents vulnerable if parental involvement is limited. The school absence policy introduced in 2016, requiring medical certificates after 10% absence, further contributed to high GP use among adolescents until it was suspended during the COVID-19 pandemic, when consultation rates dropped sharply ( 42 , 43 ). Service use in clinical subsamples Subgroup analyses of individuals with a P-diagnosis and those in contact with child and adolescent mental health services at age 17 revealed patterns of specialist and GP use that mirrored those of the general population. Together with population studies ( 28 ), this indicates that mental health needs do not diminish at age 18 but often persist or intensify into early adulthood. The sharp decline in specialist service use after 18 is therefore unlikely to reflect reduced need, but rather administrative and structural discontinuities in the system ( 31 , 44 ). Qualitative research in Norway, for example on anorexia nervosa, shows that discontinuity after 18 is commonly linked to poor coordination and cultural mismatch between child and adult services, rather than reduced need ( 45 , 46 ). International studies report similar problems, citing insufficient overlap between providers, inconsistent treatment approaches, and limited family involvement ( 4 , 11 , 17 , 19 ). Failure to address the needs of those not qualifying for adult services has long-term consequences. Disorders such as ADHD and attachment difficulties are at particular risk of disengagement ( 47 ). These groups already experience poorer outcomes, including high emergency care use, employment difficulties, and increased involvement with justice and social care systems ( 48 , 49 ). Many eventually re-enter adult services, often only in crisis or with severe, persistent difficulties ( 50 ). GP consultations among adolescents increased steadily from 2010 until the COVID-19 pandemic, when they temporarily declined ( 43 , 51 ). These findings should not be interpreted as reflecting a genuine reduction in mental health need. Conditions such as depression, anxiety, ADHD, and eating disorders are not expected to taper off at age 18, but rather increase through late adolescence and early adulthood ( 2 , 3 ). An important interpretation of our results is therefore that the marked decline in specialist mental health use after 18 reflects a change in administrative level and the current design of services, rather than a reduction in clinical demand. Contradictory, the MILESTONE study done on multiple European countries showed that only about 20% moved to adult mental services after being in children and adolescent mental health studies. A part of the study also found that those who left did not end up using more emergency services or needing more GP consultations ( 52 , 53 ). This study might suggest that there is more to explore within the shift between children and adolescent- and adult mental health services. The systems seems to identify the most unwell adolescents, but there may be gaps in care for others who still need support ( 47 ). Poor handovers between child and adult services often involve limited planning, stricter eligibility criteria, poor information exchange, and little family involvement. These discontinuities heighten the risk of disengagement, delayed treatment, and fragmented care during a critical period. Our findings, confirmed in sub-analyses of adolescents with a P-diagnosis and those in contact with child and adolescent mental health services at age 17, provide strong evidence of a structural break in service use around age 18. This decline reflects administrative boundaries rather than reduced clinical need. To reduce these gaps, coordinated handovers, broader eligibility criteria, and stronger transitional support are essential to ensure that young people continue to receive appropriate care as they move into adulthood. Strengths and limitations We gathered information on the whole Norwegian population, allowing detailed analyses of adolescents’ and young adults’ healthcare use. However, we could not cover exact information on need for health care services. We used data on mental health diagnoses set by a GP, however this could be considered a crude measure not formulated for research purposes. Still, findings may generalize to similar healthcare systems given rising youth mental health issues globally ( 1 ). Continuous registry data enabled 13-year follow-up, though lack of municipal health service data restricts a fuller picture (Reitan & Lien, 2023). GP reluctance to apply psychiatric labels may also understate psychological problems, which can be hidden under alternative diagnoses ( 54 ). Conclusion This large registry study highlights the importance of how health services are organized around the age of 18. It shows a decline in specialist mental health care use and a rise in GP reliance across the adolescent and young adult population. Subgroup analyses confirmed that these patterns persist even among those with previously documented mental health conditions or recent child and adolescent mental health service engagement, which states that they cannot be explained by reduced need. Instead, our findings reflect the current design of mental health services, where administrative boundaries, stricter eligibility criteria, and poorly coordinated handovers drive discontinuity. Poor transitions place additional responsibility on young people at a time when autonomy is still under development and extra financial barriers may further reduce access. These gaps are particularly concerning given evidence that mental health problems often intensify, rather than decline, during late adolescence and early adulthood. Abbreviations GP General Practitioner Out-of-hour GP Out-of-hours General Practitioner P-diagnosis a contact with a GP with one or more psychological symptoms Declarations Ethics and dissemination The personal data is anonymized by researchers, assuring that individual patients or professionals cannot be identified from the findings. Patient consent is not necessary for this registry study, which has been approved by the Regional Committees for Medical and Health Research Ethics (Rek number 485899). To safeguard data privacy, we utilize HUNT Cloud, a secure scientific infrastructure for data storage and processing, certified according to international standards for information security (ISO27001) and quality management (ISO 9001). Only four designated project employees have access to the data management room where all linked data is compiled and prepared for subprojects, including the one outlined in this protocol. The processed data is then transferred to an analysis room accessible to the main author and data managers. Data preparation for this project is carried out by KSA and AA. We will adhere to the STROBE guideline for observational case-control studies in reporting our findings, publishing them as scientific papers in peer-reviewed journals, and presenting them as scientific conferences. Our findings are likely to be relevant to administrators, policymakers, clinicians in primary and specialist healthcare, and other researchers. We aim to disseminate our work to all stakeholders, tailoring content and format to suit each audience. Consent for publication Availability of data and materials Norwegian registers are available to researchers pending on approval from relevant Norwegian authorities. Competing interests The authors declare no competing interests. Funding This work was supported by the Norwegian Ministry of Education and Research through a PhD fellowship position. Authors' information and contributions SEL, JHB, AA, SMN, and OB contributed to the planning, execution, and reporting of the work presented in this article. SEL performed the statistical analyses under the supervision of JHB. AA was responsible for data extraction. SEL, JHB, and OB had overall responsibility for the content and accepted full accountabilities for all aspects of the work. The corresponding author confirms that all listed authors meet authorship criteria and that no eligible individuals have been omitted. 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Scand J Prim Health Care 41(4):505–515 Appleton R, Elahi F, Tuomainen H, Canaway A, Singh SP (2021) I’m just a long history of people rejecting referrals experiences of young people who fell through the gap between child and adult mental health services. Eur Child Adolesc Psychiatry 30(3):401–413 Hall CL, Newell K, Taylor J, Sayal K, Hollis C (2015) Services for young people with attention deficit/hyperactivity disorder transitioning from child to adult mental health services: a national survey of mental health trusts in England. J Psychopharmacol 29(1):39–42 Landsem MM, Magnussen J (2018) The effect of copayments on the utilization of the GP service in Norway. Soc Sci Med 205:99–106 O’Brien A, Fahmy R, Singh SP (2009) Disengagement from mental health services: a literature review. Soc Psychiatry Psychiatr Epidemiol 44:558–568 MacKinnon N, Colman I (2016) Factors associated with suicidal thought and help-seeking behaviour in transition-aged youth versus adults. Can J Psychiatry 61(12):789–796 Clement S, Schauman O, Graham T, Maggioni F, Evans-Lacko S, Bezborodovs N et al (2015) What is the impact of mental health-related stigma on help-seeking? A systematic review of quantitative and qualitative studies. Psychol Med 45(1):11–27 Salaheddin K, Mason B (2016) Identifying barriers to mental health help-seeking among young adults in the UK: a cross-sectional survey. Br J Gen Pract 66(651):e686–e92 Gulliver A, Griffiths KM, Christensen H (2010) Perceived barriers and facilitators to mental health help-seeking in young people: a systematic review. BMC Psychiatry 10:1–9 Rickwood DJ, Deane FP, Wilson CJ (2007) When and how do young people seek professional help for mental health problems? Med J Aust 187(S7):S35–S9 Buckman JE, Saunders R, Stott J, Cohen ZD, Arundell L-L, Eley TC et al (2022) Socioeconomic indicators of treatment prognosis for adults with depression: a systematic review and individual patient data meta-analysis. JAMA psychiatry 79(5):406–416 McDaid D, Park A-L, Wahlbeck K (2019) The economic case for the prevention of mental illness. Annu Rev Public Health 40(1):373–389 Texmon I (2025) Fastlegekonsultasjoner økte mest blant grunnskolebarn: SSB; [Available from: https://www.ssb.no/helse/helsetjenester/statistikk/allmennlegetjenesten/artikler/fastlegekonsultasjoner-okte-mest-blant-grunnskolebarn Statistics Norway S (2025) GPs and emergency primary health care: Statistics Norway; [Available from: https://www.ssb.no/en/statbank/list/fastlegetj Hendrickx G, De Roeck V, Maras A, Dieleman G, Gerritsen S, Purper-Ouakil D et al (2020) Challenges during the transition from child and adolescent mental health services to adult mental health services. BJPsych Bull 44(4):163–168 Lockertsen V (2022) Mind the Gap Between CAMHS and AMHS: The Perspectives Of Patients with Anorexia Nervosa, Parents and Professionals Lockertsen V, Holm LAW, Nilsen L, Rø Ø, Burger LM, Røssberg JI (2021) The transition process between child and adolescent mental services and adult mental health services for patients with anorexia nervosa: a qualitative study of the parents’ experiences. J Eat Disorders 9(1):45 Hansen CØ, Thorup AAE, Nordentoft M, Hjorthøj C (2023) Predictors of transfer and prognosis after transfer from child and adolescent mental health services to adult mental health services—a Danish nationwide prospective register-based cohort study. Eur Child Adolesc Psychiatry. :1–9 Birnbaum HG, Kessler RC, Lowe SW, Secnik K, Greenberg PE, Leong SA et al (2005) Costs of attention deficit–hyperactivity disorder (ADHD) in the US: excess costs of persons with ADHD and their family members in 2000. Curr Med Res Opin 21(2):195–205 Leibson CL, Long KH (2003) Economic implications of attention-deficit hyperactivity disorder for healthcare systems. PharmacoEconomics 21:1239–1262 Dalsgaard S, Mortensen PB, Frydenberg M, Thomsen PH (2002) Conduct problems, gender and adult psychiatric outcome of children with attention-deficit hyperactivity disorder. Br J Psychiatry 181(5):416–421 Bakken IJL, Wensaas K-A, Furu K, Grøneng GM, Stoltenberg C, Øverland S et al (2017) Legesøkning og legemiddeluttak etter innføring av nye fraværsregler. Tidsskrift for Den norske legeforening Gerritsen SE, Van Bodegom LS, Overbeek MM, Maras A, Verhulst FC, Wolke D et al (2022) Leaving child and adolescent mental health services in the MILESTONE cohort: a longitudinal cohort study on young people's mental health indicators, care pathways, and outcomes in Europe. Lancet Psychiatry 9(12):944–956 Ford T, Anderson JK (2022) A MILESTONE study of youth service transitions in Europe. Lancet Psychiatry 9(12):930–931 Iliffe S, Williams G, Fernandez V, Vila M, Kramer T, Gledhill J et al (2008) General practitioners’ understanding of depression in young people: qualitative study. Prim Health Care Res Dev 9(4):269–279 Graphs Graphs 1 to 5 are available in the Supplementary Files section. Tables Tables 1 to 5 are available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Attachmentpaper.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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10:32:30\",\"extension\":\"docx\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"supplement\",\"size\":142513,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"Attachmentpaper.docx\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8133858/v1/4184129d220415d4fbb382c1.docx\"}],\"financialInterests\":\"No competing interests reported.\",\"formattedTitle\":\"Crossing the divide: Use of health services during the handover period from child and adolescent to adult mental health services, 2008-2021. A Norwegian National register study.\",\"fulltext\":[{\"header\":\"Background\",\"content\":\"\\u003cp\\u003eThe prevalence of psychological distress and mental disorders in adolescents and young adults is steadily increasing, along with their overall impact on individuals and society (\\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e). This is a developmental period marked by vulnerability for onset of mental health disorders (\\u003cspan citationid=\\\"CR2\\\" class=\\\"CitationRef\\\"\\u003e2\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e3\\u003c/span\\u003e). Adolescents typically receive care from children and adolescent mental health services and transition to adult mental health services around age 18. This handover is frequently characterized by fragmentation and discontinuity, leading to drop-out or delays in care (\\u003cspan citationid=\\\"CR4\\\" class=\\\"CitationRef\\\"\\u003e4\\u003c/span\\u003e). General practitioners (GPs), including out-of-hours services, often serve as the first point of contact, yet may lack the resources to manage complex mental health needs (\\u003cspan additionalcitationids=\\\"CR6\\\" citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e5\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e7\\u003c/span\\u003e). Somatic health services may also be involved, particularly when mental health issues present physical symptoms or self-harm, but integration with psychiatric services remains limited. While the appropriate level of service use is not well established, challenges in coordination are likely to affect continuity of care during this critical window.\\u003c/p\\u003e\\u003cp\\u003eAdolescence is also a period of critical life transitions such as completing high school, entering higher education or employment, moving out of the family home, and developing autonomy (\\u003cspan additionalcitationids=\\\"CR9 CR10\\\" citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e8\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e11\\u003c/span\\u003e). For adolescents facing mental health challenges, the combination of increased responsibilities and service disruptions can be particularly difficult. These challenges have been associated with adverse outcomes, including educational disruption, difficulties entering the workforce, reduced social independence, and increased contact with the criminal justice system (\\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e8\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR12\\\" class=\\\"CitationRef\\\"\\u003e12\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e13\\u003c/span\\u003e).\\u003c/p\\u003e\\u003cp\\u003eIn many countries, the separation between child and adolescent and adult mental health services at age 18 poses a barrier to continued care (\\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e14\\u003c/span\\u003e). Entry into adult services often requires meeting more stringent criteria, including symptom severity thresholds, co-payment, and regular attendance (\\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e9\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e15\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e16\\u003c/span\\u003e). Research from different health care systems shows that this transition is often poorly coordinated, with limited joint planning, differing eligibility criteria, and cultural differences between the services. These issues may stem from the two services having different models of care: child and adolescent care typically offers holistic support and addresses a broader spectrum of less severe difficulties, while adult services focus on treating more severe psychiatric disorders within a biomedical framework (\\u003cspan citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e10\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e17\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR18\\\" class=\\\"CitationRef\\\"\\u003e18\\u003c/span\\u003e). The abrupt shift in services combined with broader developmental challenges often reduces engagement during this period. Financial barriers may further contribute, where young people are required to pay user fees for GP visits from age 16, while co-payments for specialist mental health services apply from age of 18 in Norway.\\u003c/p\\u003e\\u003cp\\u003eSome young people disengage even before transition age, particularly those with milder symptoms or inconsistent attendance, resulting in further gaps in care (\\u003cspan citationid=\\\"CR19\\\" class=\\\"CitationRef\\\"\\u003e19\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR20\\\" class=\\\"CitationRef\\\"\\u003e20\\u003c/span\\u003e). Poorly coordinated handovers and limited treatment options exacerbate discontinuity and can significantly affect service users, caregivers, and the capacity of mental health services to deliver high-quality care (\\u003cspan citationid=\\\"CR6\\\" class=\\\"CitationRef\\\"\\u003e6\\u003c/span\\u003e, \\u003cspan additionalcitationids=\\\"CR22\\\" citationid=\\\"CR21\\\" class=\\\"CitationRef\\\"\\u003e21\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR23\\\" class=\\\"CitationRef\\\"\\u003e23\\u003c/span\\u003e)\\u003c/p\\u003e\\u003cp\\u003eThe aim of this study is to investigate patterns of health service use between ages 15 and 21, covering the period in which many adolescents transition from child and adolescent to adult mental health services.\\u003c/p\\u003e\"},{\"header\":\"Methods\",\"content\":\"\\u003cdiv id=\\\"Sec3\\\" class=\\\"Section2\\\"\\u003e\\u003ch2\\u003eSetting\\u003c/h2\\u003e\\u003cp\\u003eNorway provides universal healthcare with equal access across two administrative levels. Specialist care, including hospitals and mental health services, is managed by regional health authorities, while municipalities oversee primary care such as GPs and social services. National health registries cover the entire population and include information on service type, frequency, and diagnoses in child and adolescent mental health care (\\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e24\\u003c/span\\u003e).\\u003c/p\\u003e\\u003cp\\u003e Child and adolescent mental health services provide specialized care for individuals under 18, with some flexibility up to 21. Referrals typically come from GPs, school health services, or child welfare services. Services include outpatient clinics, day treatment, and inpatient units, mainly within public hospitals. At age 18, patients are eligible for adult mental health services, which are regulated by the Mental Health Care Act and the Specialist Health Services Act. Until now, user fees have applied from age 18, but from 2025 services will be free up to age 27. Contract specialists, typically psychologists, in own practices, are also engaged through government contracts to provide outpatient services. Coordination remains challenging due to separate laws and administrative structures for child and adult services. From birth, all individuals are entitled to a named regular GP, facilitating continuous care, including mental health support and coordination across services (\\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e25\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR26\\\" class=\\\"CitationRef\\\"\\u003e26\\u003c/span\\u003e). Both regular GP consultations and out-of-hours GP services are available, with the latter operating 24/7. Co-payments for both types of GP services are introduced at age 16. Somatic healthcare includes hospital admissions, outpatient contacts and surgeries, while acute somatic care provides 24-hour emergency access.\\u003c/p\\u003e\\u003c/div\\u003e\\n\\u003ch3\\u003eData sources and variables\\u003c/h3\\u003e\\n\\u003cp\\u003eUsing a de-identified unique linkage key, based on the personal ID number, we linked data across national health and administrative registers. We used data from the Norwegian Patient Registry, which contains specialist care data, and the Control and Payment of Health Reimbursement (KUHR) database, which records primary care activity, including mental health diagnoses, coded as P-codes in the ICPC-2 system (\\u003cspan citationid=\\\"CR27\\\" class=\\\"CitationRef\\\"\\u003e27\\u003c/span\\u003e). Background demographic data was available from Statistics Norway. Statistics Norway provided demographic and educational data for individuals and parents. KUHR included information on GP affiliation and out-of-hours GP use. The Norwegian Patient Registry contained ICD-10 diagnoses, specialist mental health contacts, and hospital admissions.\\u003c/p\\u003e\\n\\u003ch3\\u003eStudy population\\u003c/h3\\u003e\\n\\u003cp\\u003eThe study included 1,313,077 individuals aged 15\\u0026ndash;21 between 2008 and 2021. Subgroup analyses examined individuals with a P diagnosis (N\\u0026thinsp;=\\u0026thinsp;372,109) in GP records. They also included individuals with at least one contact in child and adolescent mental health services aged 17 (N\\u0026thinsp;=\\u0026thinsp;71, 779), representing those potentially eligible for continued specialist care.\\u003c/p\\u003e\\n\\u003ch3\\u003eCovariates\\u003c/h3\\u003e\\n\\u003cp\\u003eCovariates included age, sex, immigration status, educational attainment, parental education, and calendar year. Foreign born were defined as foreign-born individuals with two foreign-born parents and four foreign-born grandparents. Norwegian born were therefore individuals born in Norway. Parental education grouped as low parental education included primary, lower secondary, upper secondary and short post-secondary education. High parental education was presented as bachelor\\u0026rsquo;s level and beyond to indicate socioeconomic status. The individuals\\u0026rsquo; educational attainments were grouped as high or low, where their last reported educational achievement was used. Low educational attainment was grouped as finished upper secondary/high school, while high educational attainment was grouped as finished any education above secondary/high school level. ICPC-2- P- diagnosis (P-diagnosis), as an indicator of psychological symptoms, status was defined as \\u0026ldquo;ever\\u0026rdquo; versus \\u0026ldquo;never\\u0026rdquo;. Calendar year was included to control temporal trends.\\u003c/p\\u003e\\u003cdiv id=\\\"Sec7\\\" class=\\\"Section2\\\"\\u003e\\u003ch2\\u003eStatistical analysis\\u003c/h2\\u003e\\u003cp\\u003eAnalyses were conducted with STATA/MP 18.0. Using a panel data longitudinal dataset, we analyzed the number of contacts with child and adolescent mental health care, adult mental healthcare, GP, out-of-hours GP, somatic care and acute somatic care using panel data methods to be able to observe individuals at multiple times over years to control for unobservable heterogeneity and estimate effects more precisely. We used Poisson regression, with standard errors clustered at the individual level to account for correlated observations. We adjusted for variations between the calendar years with dummy variables for each year of follow-up, and for sex. The study also presents descriptive statistics for the whole population health care use showing mean, standard deviation, minimum and maximum contacts within each health care service.\\u003c/p\\u003e\\u003c/div\\u003e\\u003cdiv id=\\\"Sec8\\\" class=\\\"Section2\\\"\\u003e\\u003ch2\\u003eSubgroup analyses\\u003c/h2\\u003e\\u003cp\\u003eTo assess continuity of care among those with established mental health needs, we conducted two subgroup analyses. First, we examined individuals with at least one P-diagnosis recorded in GP or out-of-hours GP services (N\\u0026thinsp;=\\u0026thinsp;372,108). Second, we analyzed those with contact with child and adolescent mental health services at age 17 (N\\u0026thinsp;=\\u0026thinsp;71,779), representing patients who in principle could require continued follow-up in adult services. These subgroups allowed us to evaluate whether observed age-related changes reflected the general population only, or also those with documented or ongoing specialist care needs.\\u003c/p\\u003e\\u003c/div\\u003e\"},{\"header\":\"Results\",\"content\":\"\\u003cdiv id=\\\"Sec10\\\" class=\\\"Section2\\\"\\u003e\\u003ch2\\u003eDescriptive statistics\\u003c/h2\\u003e\\u003cp\\u003eTable\\u0026nbsp;1 shows that, on average, individuals had 1.55 contacts with a general practitioner (GP) per year, making this the most frequently used service. Contacts with specialist mental health services were less common (mean\\u0026thinsp;=\\u0026thinsp;0.54), followed by somatic and acute somatic services (mean\\u0026thinsp;=\\u0026thinsp;0.51) and out-of-hours GP services (mean\\u0026thinsp;=\\u0026thinsp;0.27) (Table\\u0026nbsp;1). The mean number of contacts associated with a mental diagnosis was 0.25 per person per year, indicating that a relatively small proportion of total healthcare use involved a recorded mental health diagnosis. Table\\u0026nbsp;1 revealed distinct age-related patterns across service types. The mean number of contacts with specialist mental health services declined with age, from 0.66 at age 15 to 0.40 at age 21. In contrast, contacts with GP increased steadily, from a mean of 1.20 at age 15 to 1.75 at age 21, while out-of-hours GP contacts rose from 0.20 to 0.31 over the same period. The mean number of contacts for somatic and acute somatic care remained relatively stable, ranging from 0.51 at age 15 to 0.55 at age 21. Additionally, GP and out-of-hours GP contacts involving a psychiatric diagnosis increased with age, from 0.19 at age 15 to 0.33 at age 21.\\u003c/p\\u003e\\u003c/div\\u003e\\u003cdiv id=\\\"Sec11\\\" class=\\\"Section2\\\"\\u003e\\u003ch2\\u003ePrimary analysis - Health care service utilization\\u003c/h2\\u003e\\u003cp\\u003eUse of GP services increased steadily with age, from a relative ratio (RR) at 0.92 for the age of 16 (95%CI 0.92\\u0026ndash;0.92) to a RR of 1.21 at age 19 (95%CI 1.21\\u0026ndash;1.22) and remained stable through age 21 compared with the age of 15 (table 2). The same pattern was visible in the use of out-of-hours GP services, a sharp increase during late adolescence, with a RR\\u0026thinsp;=\\u0026thinsp;0.80 at age 16 (95%CI 0.79\\u0026ndash;0.80) and peaking at the age of 19\\u0026thinsp;=\\u0026thinsp;1.28 (95%CI 1.27\\u0026ndash;1.28) relative to the age of 15. Indicating a growing reliance on primary care as adolescents transition into adulthood. The out-of-hour GP use declined slightly to a RR\\u0026thinsp;=\\u0026thinsp;1.07 by age 21 (95%CI 1.06\\u0026ndash;1.08) compared to the reference age, suggesting that acute help-seeking outside regular hours becomes more frequent toward the end of adolescence but stabilizes thereafter. Specialist mental health services were most frequently used in mid-adolescence, with a RR\\u0026thinsp;=\\u0026thinsp;1.23 at age 16 (95%CI 1.22\\u0026ndash;1.24) and 1.31 at age 18 (95%CI 1.30\\u0026ndash;1.33) compared to the 15-year-olds. However, use declined notably after age 18, reaching RR\\u0026thinsp;=\\u0026thinsp;0.72 at age 19 (95%CI 0.71\\u0026ndash;0.73) and remaining below the reference level at older ages, until 21. This indicates a substantial drop in specialist mental health service engagement in early adulthood. For acute somatic services, use remained relatively stable but with minor fluctuations. RRs ranged from 0.89 at age 16 (95%CI 0.87\\u0026ndash;0.90) to 1.10 at age 21 (95%CI 1.08\\u0026ndash;1.11) relative to the age of 15, suggesting a small increase in physical health service utilization with age.\\u003c/p\\u003e\\u003c/div\\u003e\\u003cdiv id=\\\"Sec12\\\" class=\\\"Section2\\\"\\u003e\\u003ch2\\u003eSubgroup analysis 1 - Health Care Utilization for the ones with P-diagnosis\\u003c/h2\\u003e\\u003cp\\u003eSub-analyses (Graph 3, Table\\u0026nbsp;3) revealed the use of general practitioner and out-of-hours GP services remained relatively stable across ages for adolescents with a p diagnosis, with a slightly higher use of GP\\u0026thinsp;=\\u0026thinsp;1.14 (95% CI 1.14-1-15) and out-of-hours GP at 19 at 1.22 (95% CI 1.21\\u0026ndash;1.23) relative to the 15 year olds within the same group. Those with a P-diagnosis had the highest use of specialist mental health services at age 18 RR 1.31 (95%CI 1.30\\u0026ndash;1.32), with a drop to 0.73 (95% CI 0.72\\u0026ndash;0.73) within the age of 19 relative to the age of 15. The RR rose steadily to 1.10 by the age 21 (95% CI 1.09\\u0026ndash;1.12). The use of specialist mental health services for this group declined after the age of 18, with an RR of 1.23 at the age of 16 (95% CI 1.22\\u0026ndash;1.24) and to 0.87 by the end of age 18 (95% CI 0.86\\u0026ndash;0.88) compared to the age of 15.\\u003c/p\\u003e\\u003cp\\u003eAmong individuals without a P-diagnosis, there was a gradual increase in GP use with age (table 3, graph 3), where the RR was 0.91 (95% CI 0.90\\u0026ndash;0.91) at age 16 and peaked at 1.29 (95% CI 1.29\\u0026ndash;1.29) at age 19, relative to age 15. GP use stabilized by age 21 with an RR of 1.04 (95% CI 1.04\\u0026ndash;1.05). For out-of-hours GP consultations, use increased from RR 0.80 (95% CI 0.79\\u0026ndash;0.80) at age 16 to RR 1.33 (95% CI 1.32\\u0026ndash;1.34) at age 19, before stabilizing around RR 1.06 (95% CI 1.05\\u0026ndash;1.07) by age 21. In contrast, specialist mental health service use declined markedly after mid-adolescence, with RR 1.23 (95% CI 1.20\\u0026ndash;1.26) at age 16, peaking at RR 1.47 (95% CI 1.42\\u0026ndash;1.53) at age 18 relative to the age of 15. The use of out-of-hour GP dropped to a RR of 1.08 (95% CI 1.00-1.16) by age 21, with the lowest use observed at age 20 (RR 0.57, 95% CI 0.54\\u0026ndash;0.61) compared to 15. Acute somatic and somatic service utilization remained relatively stable across ages, showing only minor increases from RR 1.06 (95% CI 1.05\\u0026ndash;1.07) at age 16 to RR 1.08 (95% CI 1.07\\u0026ndash;1.09) at age 21, suggesting consistent use of somatic and emergency care throughout late adolescence and early adulthood.\\u003c/p\\u003e\\u003cp\\u003e\\u003cb\\u003eSubgroup analysis 2 - Mental health utilization for the population with one or more contacts in child and adolescent mental health services the year they turned 17\\u003c/b\\u003e\\u003c/p\\u003e\\u003cp\\u003eSub-analysis within the population with one or more contacts in child and adolescent mental health services the year they turned 17 (Table\\u0026nbsp;5, graph 5) showed smaller to no increases in GP use with a RR at 0.96 (95% CI 0.96\\u0026ndash;0.97) at age 16 and RR of 1.04 at age 18 (95% CI 1.04\\u0026ndash;1.05) compared to the age of 15. The use of out-of-hours GP services had a higher rise, whereas at 16 the RR was 0.85 (95% CI 0.83\\u0026ndash;0.86) and 1.11 at the age of 18 (95% CI 1.1\\u0026ndash;1.15) relative to the age of 15. Regardless of gender, parental education, education, immigration background, or diagnostic status, there was a marked reduction in specialist mental health utilization beginning at age 18, with RR dropping steadily to their lowest levels around age 20 (Table\\u0026nbsp;5). The overall RR for the use of specialist mental health services for this population (table 6 and graph 5) declined from 1.58 (95% CI 1.56\\u0026ndash;1.59) at age 18 to 0.74 (95% CI 0.73\\u0026ndash;0.76) by age 21 compared to 15. Utilization of acute somatic and somatic services remained stable across the age span with modest fluctuation in RR. The findings for this subgroup were interpreted cautiously due to potential regression to the mean.\\u003c/p\\u003e\\u003c/div\\u003e\"},{\"header\":\"Discussion\",\"content\":\"\\u003cdiv id=\\\"Sec14\\\" class=\\\"Section2\\\"\\u003e\\u003ch2\\u003eMain findings\\u003c/h2\\u003e\\u003cp\\u003eThe main findings from this study of 1.3\\u0026nbsp;million Norwegian adolescents and young adults showed a marked decrease in specialist mental health service use, accompanied by an increase in consultations with GPs and out-of-hours GP services after age 18, coinciding with the crossing from child and adolescent to adult mental health services. The reduction in use of specialist mental health services was also evident in subgroup analyses of individuals with a mental health diagnosis set by a GP and those with contact with child and adolescent services at age 17.\\u003c/p\\u003e\\u003c/div\\u003e\\u003cdiv id=\\\"Sec15\\\" class=\\\"Section2\\\"\\u003e\\u003ch2\\u003eHealth Service utilization in adolescents and young adult population\\u003c/h2\\u003e\\u003cp\\u003eResults from the Norwegian Young HUNT study show a marked rise in adolescent anxiety and depression symptom level over the past two decades (\\u003cspan citationid=\\\"CR28\\\" class=\\\"CitationRef\\\"\\u003e28\\u003c/span\\u003e). Against this backdrop, our results revealed a decline in specialist service use and a simultaneous increase in GP and out-of-hours GP consultations after age 18, despite continued or growing mental health needs in this age group.\\u003c/p\\u003e\\u003cp\\u003eThis shift reflects both a shortfall in adult mental health capacity and the structural handover at age 18, when many adolescents are discharged from child services without coordinated transfer to adult care (\\u003cspan citationid=\\\"CR19\\\" class=\\\"CitationRef\\\"\\u003e19\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR29\\\" class=\\\"CitationRef\\\"\\u003e29\\u003c/span\\u003e). GP consultations increasingly involve psychosocial issues and conversation therapy (\\u003cspan citationid=\\\"CR30\\\" class=\\\"CitationRef\\\"\\u003e30\\u003c/span\\u003e), but concerns remain about whether primary care has sufficient resources and expertise to manage complex mental health conditions (\\u003cspan citationid=\\\"CR31\\\" class=\\\"CitationRef\\\"\\u003e31\\u003c/span\\u003e). As young people age out of children\\u0026rsquo;s mental health services, many find themselves with limited alternatives, particularly in regions where adults mental health capacity is stretched or thresholds for acceptance are high (\\u003cspan citationid=\\\"CR18\\\" class=\\\"CitationRef\\\"\\u003e18\\u003c/span\\u003e).\\u003c/p\\u003e\\u003cp\\u003eFinancial factors also play a role. In Norway, co-payments begin at age 16 for GP visits and at 18 for specialist mental health services, with specialist care substantially more expensive. The observed rise in GP use may therefore reflect both gaps in specialist availability and relative affordability, as child services often discharge young adults to their GP after 18 (\\u003cspan citationid=\\\"CR32\\\" class=\\\"CitationRef\\\"\\u003e32\\u003c/span\\u003e). Earlier studies found reduced GP use after the introduction of co-payments, suggesting that the increase we observe represents a structural shift in service provision rather than a decline in need (\\u003cspan citationid=\\\"CR33\\\" class=\\\"CitationRef\\\"\\u003e33\\u003c/span\\u003e). Norway is however subsidized, having an annual user fee of maximum NOK 3278, where one visit to the GP is approximately NOK 240 and a visit to the specialist mental health services after the age of 18 is maximum NOK 386.\\u003c/p\\u003e\\u003cp\\u003eDespite this reliance on GPs, barriers to care remain high. Young people are less likely than adults to seek professional help for conditions such as depression (\\u003cspan citationid=\\\"CR34\\\" class=\\\"CitationRef\\\"\\u003e34\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR35\\\" class=\\\"CitationRef\\\"\\u003e35\\u003c/span\\u003e). Stigma, confidentiality concerns, reliance on informal support, and difficulties navigating the health system are common obstacle (\\u003cspan additionalcitationids=\\\"CR37\\\" citationid=\\\"CR36\\\" class=\\\"CitationRef\\\"\\u003e36\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR38\\\" class=\\\"CitationRef\\\"\\u003e38\\u003c/span\\u003e). Barriers are especially pronounced among males and those from minority or indigenous backgrounds (\\u003cspan citationid=\\\"CR39\\\" class=\\\"CitationRef\\\"\\u003e39\\u003c/span\\u003e). Even adolescents with high symptom levels may disengage, particularly when faced with the new responsibility of scheduling appointments, renewing prescriptions, and adherent to treatment.\\u003c/p\\u003e\\u003cp\\u003eDisengagement at this vulnerable stage increases risks of symptom worsening, unemployment, and long-term social exclusion, as well as a lack of trust to the health care system, motivation and hope for the future (\\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e17\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR40\\\" class=\\\"CitationRef\\\"\\u003e40\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR41\\\" class=\\\"CitationRef\\\"\\u003e41\\u003c/span\\u003e). Legal autonomy in health matters from age 16 may also leave some adolescents vulnerable if parental involvement is limited. The school absence policy introduced in 2016, requiring medical certificates after 10% absence, further contributed to high GP use among adolescents until it was suspended during the COVID-19 pandemic, when consultation rates dropped sharply (\\u003cspan citationid=\\\"CR42\\\" class=\\\"CitationRef\\\"\\u003e42\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR43\\\" class=\\\"CitationRef\\\"\\u003e43\\u003c/span\\u003e).\\u003c/p\\u003e\\u003c/div\\u003e\\u003cdiv id=\\\"Sec16\\\" class=\\\"Section2\\\"\\u003e\\u003ch2\\u003eService use in clinical subsamples\\u003c/h2\\u003e\\u003cp\\u003eSubgroup analyses of individuals with a P-diagnosis and those in contact with child and adolescent mental health services at age 17 revealed patterns of specialist and GP use that mirrored those of the general population. Together with population studies (\\u003cspan citationid=\\\"CR28\\\" class=\\\"CitationRef\\\"\\u003e28\\u003c/span\\u003e), this indicates that mental health needs do not diminish at age 18 but often persist or intensify into early adulthood. The sharp decline in specialist service use after 18 is therefore unlikely to reflect reduced need, but rather administrative and structural discontinuities in the system (\\u003cspan citationid=\\\"CR31\\\" class=\\\"CitationRef\\\"\\u003e31\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR44\\\" class=\\\"CitationRef\\\"\\u003e44\\u003c/span\\u003e).\\u003c/p\\u003e\\u003cp\\u003eQualitative research in Norway, for example on anorexia nervosa, shows that discontinuity after 18 is commonly linked to poor coordination and cultural mismatch between child and adult services, rather than reduced need (\\u003cspan citationid=\\\"CR45\\\" class=\\\"CitationRef\\\"\\u003e45\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR46\\\" class=\\\"CitationRef\\\"\\u003e46\\u003c/span\\u003e). International studies report similar problems, citing insufficient overlap between providers, inconsistent treatment approaches, and limited family involvement (\\u003cspan citationid=\\\"CR4\\\" class=\\\"CitationRef\\\"\\u003e4\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e11\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e17\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR19\\\" class=\\\"CitationRef\\\"\\u003e19\\u003c/span\\u003e).\\u003c/p\\u003e\\u003cp\\u003eFailure to address the needs of those not qualifying for adult services has long-term consequences. Disorders such as ADHD and attachment difficulties are at particular risk of disengagement (\\u003cspan citationid=\\\"CR47\\\" class=\\\"CitationRef\\\"\\u003e47\\u003c/span\\u003e). These groups already experience poorer outcomes, including high emergency care use, employment difficulties, and increased involvement with justice and social care systems (\\u003cspan citationid=\\\"CR48\\\" class=\\\"CitationRef\\\"\\u003e48\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR49\\\" class=\\\"CitationRef\\\"\\u003e49\\u003c/span\\u003e). Many eventually re-enter adult services, often only in crisis or with severe, persistent difficulties (\\u003cspan citationid=\\\"CR50\\\" class=\\\"CitationRef\\\"\\u003e50\\u003c/span\\u003e). GP consultations among adolescents increased steadily from 2010 until the COVID-19 pandemic, when they temporarily declined (\\u003cspan citationid=\\\"CR43\\\" class=\\\"CitationRef\\\"\\u003e43\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR51\\\" class=\\\"CitationRef\\\"\\u003e51\\u003c/span\\u003e).\\u003c/p\\u003e\\u003cp\\u003eThese findings should not be interpreted as reflecting a genuine reduction in mental health need. Conditions such as depression, anxiety, ADHD, and eating disorders are not expected to taper off at age 18, but rather increase through late adolescence and early adulthood (\\u003cspan citationid=\\\"CR2\\\" class=\\\"CitationRef\\\"\\u003e2\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e3\\u003c/span\\u003e). An important interpretation of our results is therefore that the marked decline in specialist mental health use after 18 reflects a change in administrative level and the current design of services, rather than a reduction in clinical demand.\\u003c/p\\u003e\\u003cp\\u003eContradictory, the MILESTONE study done on multiple European countries showed that only about 20% moved to adult mental services after being in children and adolescent mental health studies. A part of the study also found that those who left did not end up using more emergency services or needing more GP consultations (\\u003cspan citationid=\\\"CR52\\\" class=\\\"CitationRef\\\"\\u003e52\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR53\\\" class=\\\"CitationRef\\\"\\u003e53\\u003c/span\\u003e). This study might suggest that there is more to explore within the shift between children and adolescent- and adult mental health services. The systems seems to identify the most unwell adolescents, but there may be gaps in care for others who still need support (\\u003cspan citationid=\\\"CR47\\\" class=\\\"CitationRef\\\"\\u003e47\\u003c/span\\u003e).\\u003c/p\\u003e\\u003cp\\u003ePoor handovers between child and adult services often involve limited planning, stricter eligibility criteria, poor information exchange, and little family involvement. These discontinuities heighten the risk of disengagement, delayed treatment, and fragmented care during a critical period. Our findings, confirmed in sub-analyses of adolescents with a P-diagnosis and those in contact with child and adolescent mental health services at age 17, provide strong evidence of a structural break in service use around age 18. This decline reflects administrative boundaries rather than reduced clinical need. To reduce these gaps, coordinated handovers, broader eligibility criteria, and stronger transitional support are essential to ensure that young people continue to receive appropriate care as they move into adulthood.\\u003c/p\\u003e\\u003c/div\\u003e\\u003cdiv id=\\\"Sec17\\\" class=\\\"Section2\\\"\\u003e\\u003ch2\\u003eStrengths and limitations\\u003c/h2\\u003e\\u003cp\\u003eWe gathered information on the whole Norwegian population, allowing detailed analyses of adolescents\\u0026rsquo; and young adults\\u0026rsquo; healthcare use. However, we could not cover exact information on need for health care services. We used data on mental health diagnoses set by a GP, however this could be considered a crude measure not formulated for research purposes. Still, findings may generalize to similar healthcare systems given rising youth mental health issues globally (\\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e). Continuous registry data enabled 13-year follow-up, though lack of municipal health service data restricts a fuller picture (Reitan \\u0026amp; Lien, 2023). GP reluctance to apply psychiatric labels may also understate psychological problems, which can be hidden under alternative diagnoses (\\u003cspan citationid=\\\"CR54\\\" class=\\\"CitationRef\\\"\\u003e54\\u003c/span\\u003e).\\u003c/p\\u003e\\u003c/div\\u003e\"},{\"header\":\"Conclusion\",\"content\":\"\\u003cp\\u003eThis large registry study highlights the importance of how health services are organized around the age of 18. It shows a decline in specialist mental health care use and a rise in GP reliance across the adolescent and young adult population. Subgroup analyses confirmed that these patterns persist even among those with previously documented mental health conditions or recent child and adolescent mental health service engagement, which states that they cannot be explained by reduced need. Instead, our findings reflect the current design of mental health services, where administrative boundaries, stricter eligibility criteria, and poorly coordinated handovers drive discontinuity. Poor transitions place additional responsibility on young people at a time when autonomy is still under development and extra financial barriers may further reduce access. These gaps are particularly concerning given evidence that mental health problems often intensify, rather than decline, during late adolescence and early adulthood.\\u003c/p\\u003e\"},{\"header\":\"Abbreviations\",\"content\":\"\\u003cdiv class=\\\"DefinitionList\\\"\\u003e\\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e\\u003cdiv class=\\\"Term\\\"\\u003eGP\\u003c/div\\u003e\\u003cdiv class=\\\"Description\\\"\\u003e\\u003cp\\u003eGeneral Practitioner\\u003c/p\\u003e\\u003c/div\\u003e\\u003c/div\\u003e\\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e\\u003cdiv class=\\\"Term\\\"\\u003eOut-of-hour GP\\u003c/div\\u003e\\u003cdiv class=\\\"Description\\\"\\u003e\\u003cp\\u003eOut-of-hours General Practitioner\\u003c/p\\u003e\\u003c/div\\u003e\\u003c/div\\u003e\\u003cdiv class=\\\"DefinitionListEntry\\\"\\u003e\\u003cdiv class=\\\"Term\\\"\\u003eP-diagnosis\\u003c/div\\u003e\\u003cdiv class=\\\"Description\\\"\\u003e\\u003cp\\u003ea contact with a GP with one or more psychological symptoms\\u003c/p\\u003e\\u003c/div\\u003e\\u003c/div\\u003e\\u003c/div\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eEthics and dissemination\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe personal data is anonymized by researchers, assuring that individual patients or professionals cannot be identified from the findings. Patient consent is not necessary for this registry study, which has been approved by the Regional Committees for Medical and Health Research Ethics (Rek number 485899). To safeguard data privacy, we utilize HUNT Cloud, a secure scientific infrastructure for data storage and processing, certified according to international standards for information security (ISO27001) and quality management (ISO 9001). Only four designated project employees have access to the data management room where all linked data is compiled and prepared for subprojects, including the one outlined in this protocol. The processed data is then transferred to an analysis room accessible to the main author and data managers. Data preparation for this project is carried out by KSA and AA. \\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003eWe will adhere to the STROBE guideline for observational case-control studies in reporting our findings, publishing them as scientific papers in peer-reviewed journals, and presenting them as scientific conferences. Our findings are likely to be relevant to administrators, policymakers, clinicians in primary and specialist healthcare, and other researchers. We aim to disseminate our work to all stakeholders, tailoring content and format to suit each audience.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eConsent for publication\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAvailability of data and materials\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eNorwegian registers are available to researchers pending on approval from relevant Norwegian authorities.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eCompeting interests\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe authors declare no competing interests.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eFunding\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThis work was supported by the Norwegian Ministry of Education and Research through a PhD fellowship position.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAuthors' information and contributions\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eSEL, JHB, AA, SMN, and OB contributed to the planning, execution, and reporting of the work presented in this article. SEL performed the statistical analyses under the supervision of JHB. AA was responsible for data extraction. SEL, JHB, and OB had overall responsibility for the content and accepted full accountabilities for all aspects of the work. The corresponding author confirms that all listed authors meet authorship criteria and that no eligible individuals have been omitted. All authors have read and approved the final version of the manuscript.\\u003c/p\\u003e\\n\\u003col\\u003e\\n \\u003cli\\u003eNord University, Faculty of Nursing and Health Sciences, Nord University, Postboks 93, Levanger 7601, Norway.\\u003c/li\\u003e\\n \\u003cli\\u003eNorwegian University of Science and Technology (NTNU), Department of Public Health and Nursing, Postboks 8905, Trondheim 7491, Norway.\\u003c/li\\u003e\\n \\u003cli\\u003eSt. Olavs Hospital, Regionalt senter for helsetjenesteutvikling St. Olavs Hospital, Postboks 3250 Sluppen, Trondheim N‑7006, Norway.\\u003c/li\\u003e\\n\\u003c/ol\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAcknowledgements\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eWe would like to thank our colleagues at NTNU, the Regforsk group and others at both Nord University and NTNU, for insightful discussions and comments.\\u0026nbsp;\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\u003cli\\u003e\\u003cspan\\u003eMcGorry PD, Mei C, Dalal N, Alvarez-Jimenez M, Blakemore S-J, Browne V et al (2024) The Lancet Psychiatry Commission on youth mental health. Lancet Psychiatry 11(9):731\\u0026ndash;774\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eArnett JJ (2000) Emerging adulthood: A theory of development from the late teens through the twenties. Am Psychol 55(5):469\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eSolmi M, Radua J, Olivola M, Croce E, Soardo L, Salazar de Pablo G et al (2022) Age at onset of mental disorders worldwide: large-scale meta-analysis of 192 epidemiological studies. Mol Psychiatry 27(1):281\\u0026ndash;295\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eSingh SP, Paul M, Ford T, Kramer T, Weaver T, McLaren S et al (2010) Process, outcome and experience of transition from child to adult mental healthcare: multiperspective study. Br J psychiatry 197(4):305\\u0026ndash;312\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eBiddle L, Donovan JL, Gunnell D, Sharp D (2006) Young adults' perceptions of GPs as a help source for mental distress: a qualitative study. Br J Gen Pract 56(533):924\\u0026ndash;931\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eAppleton R, Connell C, Fairclough E, Tuomainen H, Singh SP (2019) Outcomes of young people who reach the transition boundary of child and adolescent mental health services: a systematic review. Eur Child Adolesc Psychiatry 28(11):1431\\u0026ndash;1446\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eHansen AS, Christoffersen CH, Tell\\u0026eacute;us GK, Lauritsen MB (2021) Referral patterns to outpatient child and adolescent mental health services and factors associated with referrals being rejected. A cross-sectional observational study. BMC Health Serv Res 21:1\\u0026ndash;12\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eBecht AI, Nelemans SA, Branje SJ, Vollebergh WA, Koot HM, Denissen JJ et al (2016) The quest for identity in adolescence: Heterogeneity in daily identity formation and psychosocial adjustment across 5 years. Dev Psychol 52(12):2010\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eBroad KL, Sandhu VK, Sunderji N, Charach A (2017) Youth experiences of transition from child mental health services to adult mental health services: a qualitative thematic synthesis. BMC Psychiatry 17(1):380\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eHill A, Wilde S, Tickle A, Review (2019) Transition from Child and Adolescent Mental Health Services (CAMHS) to Adult Mental Health Services (AMHS): a meta-synthesis of parental and professional perspectives. 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J Behav Health Serv Res 35(4):373\\u0026ndash;389\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eSignorini G, Singh SP, Marsanic VB, Dieleman G, Dodig-Ćurković K, Franic T et al (2018) The interface between child/adolescent and adult mental health services: results from a European 28-country survey. Eur Child Adolesc Psychiatry 27(4):501\\u0026ndash;511\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eBoonstra A, Leijdesdorff S, Street C, Holme I, van Bodegom L, Franić T et al (2024) Turning 18 in mental health services: a multicountry qualitative study of service user experiences and views. Ir J Psychol Med. :1\\u0026ndash;9\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eDunn V (2017) Young people, mental health practitioners and researchers co-produce a Transition Preparation Programme to improve outcomes and experience for young people leaving Child and Adolescent Mental Health Services (CAMHS). 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Br J Psychiatry 202(s54):s36\\u0026ndash;s40\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eSingh SP, Paul M, Ford T, Kramer T, Weaver T (2008) Transitions of care from child and adolescent mental health services to adult mental health services (TRACK study): a study of protocols in Greater London. BMC Health Serv Res 8:1\\u0026ndash;7\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eCleverley K, Lenters L, McCann E (2020) Objectively terrifying: a qualitative study of youth\\u0026rsquo;s experiences of transitions out of child and adolescent mental health services at age 18. BMC Psychiatry 20(1):147\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003ePaul M, Street C, Wheeler N, Singh SP (2015) Transition to adult services for young people with mental health needs: A systematic review. Clin Child Psychol Psychiatry 20(3):436\\u0026ndash;457\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eSingh SP, Paul M, Ford T, Kramer T, Weaver T, McLaren S et al (2010) Process, outcome and experience of transition from child to adult mental healthcare: multiperspective study. Br J Psychiatry 197(4):305\\u0026ndash;312\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eBakken IJ, Ariansen AM, Knudsen GP, Johansen KI, Vollset SE (2020) The Norwegian Patient Registry and the Norwegian Registry for Primary Health Care: Research potential of two nationwide health-care registries. Scand J Public Health 48(1):49\\u0026ndash;55\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eSaunes IS, Karanikolos M, Sagan A, Norway (2020) Health Syst Rev Health Syst Transition 22(1):1\\u0026ndash;163\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eLov om kommunale helse- og omsorgstjenester m.m. 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ICPC-2e International Classification of Primary Care, Second Edition \\u0026ndash; English Version: Norwegian Directorate of Health; 2019 [Available from: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://www.helsedirektoratet.no/digitalisering-og-e-helse/helsefaglige-kodeverk/icpc/icpc-2e--english-version/_/attachment/inline/128bbf19-0307-4d8b-b66e-7abdbc686e1f:b1b6ccf719152365ab9668c45fb5d0aced197038/ICPC-2e-English.pdf\\u003c/span\\u003e\\u003cspan address=\\\"https://www.helsedirektoratet.no/digitalisering-og-e-helse/helsefaglige-kodeverk/icpc/icpc-2e--english-version/_/attachment/inline/128bbf19-0307-4d8b-b66e-7abdbc686e1f:b1b6ccf719152365ab9668c45fb5d0aced197038/ICPC-2e-English.pdf\\\" targettype=\\\"URL\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eKrokstad MA, Sund E, Rangul V, Bauman A, Olsson C, Bjerkeset O (2024) Secular trends in risk factors for adolescent anxiety and depression symptoms: the Young-HUNT studies 1995\\u0026ndash;2019, Norway. Eur Child Adolesc Psychiatry 33(11):3819\\u0026ndash;3827\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eSingh SP, Tuomainen H (2015) Transition from child to adult mental health services: needs, barriers, experiences and new models of care. World Psychiatry 14(3):358\\u0026ndash;361\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eWahlberg K, Pape K, Austad B, Vie G\\u0026Aring; (2023) Use of general practitioner services among youth and young adults in Norway from 2006 to 2021. Scand J Prim Health Care 41(4):505\\u0026ndash;515\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eAppleton R, Elahi F, Tuomainen H, Canaway A, Singh SP (2021) I\\u0026rsquo;m just a long history of people rejecting referrals experiences of young people who fell through the gap between child and adult mental health services. Eur Child Adolesc Psychiatry 30(3):401\\u0026ndash;413\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eHall CL, Newell K, Taylor J, Sayal K, Hollis C (2015) Services for young people with attention deficit/hyperactivity disorder transitioning from child to adult mental health services: a national survey of mental health trusts in England. J Psychopharmacol 29(1):39\\u0026ndash;42\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eLandsem MM, Magnussen J (2018) The effect of copayments on the utilization of the GP service in Norway. Soc Sci Med 205:99\\u0026ndash;106\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eO\\u0026rsquo;Brien A, Fahmy R, Singh SP (2009) Disengagement from mental health services: a literature review. Soc Psychiatry Psychiatr Epidemiol 44:558\\u0026ndash;568\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eMacKinnon N, Colman I (2016) Factors associated with suicidal thought and help-seeking behaviour in transition-aged youth versus adults. Can J Psychiatry 61(12):789\\u0026ndash;796\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eClement S, Schauman O, Graham T, Maggioni F, Evans-Lacko S, Bezborodovs N et al (2015) What is the impact of mental health-related stigma on help-seeking? A systematic review of quantitative and qualitative studies. Psychol Med 45(1):11\\u0026ndash;27\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eSalaheddin K, Mason B (2016) Identifying barriers to mental health help-seeking among young adults in the UK: a cross-sectional survey. Br J Gen Pract 66(651):e686\\u0026ndash;e92\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eGulliver A, Griffiths KM, Christensen H (2010) Perceived barriers and facilitators to mental health help-seeking in young people: a systematic review. BMC Psychiatry 10:1\\u0026ndash;9\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eRickwood DJ, Deane FP, Wilson CJ (2007) When and how do young people seek professional help for mental health problems? Med J Aust 187(S7):S35\\u0026ndash;S9\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eBuckman JE, Saunders R, Stott J, Cohen ZD, Arundell L-L, Eley TC et al (2022) Socioeconomic indicators of treatment prognosis for adults with depression: a systematic review and individual patient data meta-analysis. 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Annu Rev Public Health 40(1):373\\u0026ndash;389\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eTexmon I (2025) Fastlegekonsultasjoner \\u0026oslash;kte mest blant grunnskolebarn: SSB; [Available from: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://www.ssb.no/helse/helsetjenester/statistikk/allmennlegetjenesten/artikler/fastlegekonsultasjoner-okte-mest-blant-grunnskolebarn\\u003c/span\\u003e\\u003cspan address=\\\"https://www.ssb.no/helse/helsetjenester/statistikk/allmennlegetjenesten/artikler/fastlegekonsultasjoner-okte-mest-blant-grunnskolebarn\\\" targettype=\\\"URL\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eStatistics Norway S (2025) GPs and emergency primary health care: Statistics Norway; [Available from: \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://www.ssb.no/en/statbank/list/fastlegetj\\u003c/span\\u003e\\u003cspan address=\\\"https://www.ssb.no/en/statbank/list/fastlegetj\\\" targettype=\\\"URL\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eHendrickx G, De Roeck V, Maras A, Dieleman G, Gerritsen S, Purper-Ouakil D et al (2020) Challenges during the transition from child and adolescent mental health services to adult mental health services. BJPsych Bull 44(4):163\\u0026ndash;168\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eLockertsen V (2022) Mind the Gap Between CAMHS and AMHS: The Perspectives Of Patients with Anorexia Nervosa, Parents and Professionals\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eLockertsen V, Holm LAW, Nilsen L, R\\u0026oslash; \\u0026Oslash;, Burger LM, R\\u0026oslash;ssberg JI (2021) The transition process between child and adolescent mental services and adult mental health services for patients with anorexia nervosa: a qualitative study of the parents\\u0026rsquo; experiences. J Eat Disorders 9(1):45\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eHansen C\\u0026Oslash;, Thorup AAE, Nordentoft M, Hjorth\\u0026oslash;j C (2023) Predictors of transfer and prognosis after transfer from child and adolescent mental health services to adult mental health services\\u0026mdash;a Danish nationwide prospective register-based cohort study. Eur Child Adolesc Psychiatry. :1\\u0026ndash;9\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eBirnbaum HG, Kessler RC, Lowe SW, Secnik K, Greenberg PE, Leong SA et al (2005) Costs of attention deficit\\u0026ndash;hyperactivity disorder (ADHD) in the US: excess costs of persons with ADHD and their family members in 2000. Curr Med Res Opin 21(2):195\\u0026ndash;205\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eLeibson CL, Long KH (2003) Economic implications of attention-deficit hyperactivity disorder for healthcare systems. PharmacoEconomics 21:1239\\u0026ndash;1262\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eDalsgaard S, Mortensen PB, Frydenberg M, Thomsen PH (2002) Conduct problems, gender and adult psychiatric outcome of children with attention-deficit hyperactivity disorder. Br J Psychiatry 181(5):416\\u0026ndash;421\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eBakken IJL, Wensaas K-A, Furu K, Gr\\u0026oslash;neng GM, Stoltenberg C, \\u0026Oslash;verland S et al (2017) Leges\\u0026oslash;kning og legemiddeluttak etter innf\\u0026oslash;ring av nye frav\\u0026aelig;rsregler. Tidsskrift for Den norske legeforening\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eGerritsen SE, Van Bodegom LS, Overbeek MM, Maras A, Verhulst FC, Wolke D et al (2022) Leaving child and adolescent mental health services in the MILESTONE cohort: a longitudinal cohort study on young people's mental health indicators, care pathways, and outcomes in Europe. Lancet Psychiatry 9(12):944\\u0026ndash;956\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eFord T, Anderson JK (2022) A MILESTONE study of youth service transitions in Europe. Lancet Psychiatry 9(12):930\\u0026ndash;931\\u003c/span\\u003e\\u003c/li\\u003e\\u003cli\\u003e\\u003cspan\\u003eIliffe S, Williams G, Fernandez V, Vila M, Kramer T, Gledhill J et al (2008) General practitioners\\u0026rsquo; understanding of depression in young people: qualitative study. Prim Health Care Res Dev 9(4):269\\u0026ndash;279\\u003c/span\\u003e\\u003c/li\\u003e\\u003c/ol\\u003e\"},{\"header\":\"Graphs\",\"content\":\"\\u003cp\\u003eGraphs 1 to 5 are available in the Supplementary Files section.\\u003c/p\\u003e\"},{\"header\":\"Tables\",\"content\":\"\\u003cp\\u003eTables 1 to 5 are available in the Supplementary Files section.\\u003c/p\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":true,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":false,\"isAuthorSuppliedPdf\":false,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true},\"keywords\":\"Mental Health Services, Child and Adolescent Mental Health, Adults Mental Health, Transition of care, Health Service Utilization\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-8133858/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-8133858/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003ch2\\u003eBackground\\u003c/h2\\u003e\\u003cp\\u003eAdolescence and early adulthood represent periods of heightened vulnerability to mental health disorders. In Norway, mental health care shifts from child and adolescent mental health services to adult mental health services at age 18, which may result in fragmented transitions and treatment discontinuity. The aim of this study was to examine health service use and patterns between ages 15 and 21, with particular attention to the transition in specialist mental health services that typically occur around age 18.\\u003c/p\\u003e\\u003ch2\\u003eMethods\\u003c/h2\\u003e\\u003cp\\u003eWe conducted a population-wide registry study including all Norwegians aged 15\\u0026ndash;21 between 2008 and 2021 (n\\u0026thinsp;=\\u0026thinsp;1,313,077). Health service utilization was analyzed using Poisson regression. Subgroup analyses included individuals with established mental health needs, namely all adolescents with a GP-recorded mental health diagnosis (n\\u0026thinsp;=\\u0026thinsp;372,109) and those with child and adolescent mental health service contact at age 17 (n\\u0026thinsp;=\\u0026thinsp;71, 779).\\u003c/p\\u003e\\u003ch2\\u003eResults\\u003c/h2\\u003e\\u003cp\\u003eSpecialist mental health service use peaked at age 16, declined sharply after 18, and reached its lowest levels around 20. In contrast, GP and out-of-hours GP consultations increased steadily, particularly after age 18, while somatic and acute somatic services remained stable. The same pattern appeared in both subgroup analyses, of youth with a GP-recorded mental health diagnosis and in those with recent contact with child and adolescent mental health services at age 17.\\u003c/p\\u003e\\u003ch2\\u003eConclusion\\u003c/h2\\u003e\\u003cp\\u003eSpecialist mental health service use declines sharply after the transition to adult care, while GP reliance increases. These findings suggest structural rather than clinical causes, highlighting the need for better continuity across the change in mental health service levels.\\u003c/p\\u003e\",\"manuscriptTitle\":\"Crossing the divide: Use of health services during the handover period from child and adolescent to adult mental health services, 2008-2021. A Norwegian National register study.\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2025-12-02 10:32:25\",\"doi\":\"10.21203/rs.3.rs-8133858/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true}}],\"origin\":\"\",\"ownerIdentity\":\"ac0d7bb9-fd89-4cdc-a4cc-f8bf846370bd\",\"owner\":[],\"postedDate\":\"December 2nd, 2025\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"posted\",\"subjectAreas\":[],\"tags\":[],\"updatedAt\":\"2026-01-25T22:54:11+00:00\",\"versionOfRecord\":[],\"versionCreatedAt\":\"2025-12-02 10:32:25\",\"video\":\"\",\"vorDoi\":\"\",\"vorDoiUrl\":\"\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-8133858\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-8133858\",\"identity\":\"rs-8133858\",\"version\":[\"v1\"]},\"buildId\":\"8U1c8b4HqxoKbykW_rLl7\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}