Introducing a group-based cannabis prevention program for adolescents in youth residential care in Germany (CANJuStop): Study protocol for an exploratory randomized controlled trial

Introducing a group-based cannabis prevention program for adolescents in youth residential care in Germany (CANJuStop): Study protocol for an exploratory randomized controlled trial | 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 Study protocol Introducing a group-based cannabis prevention program for adolescents in youth residential care in Germany (CAN Ju Stop): Study protocol for an exploratory randomized controlled trial Nicolas Arnaud, Anna-Lena Schulz, Christiane Baldus, Julian Harbs, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8394115/v2 This work is licensed under a CC BY 4.0 License Status: Posted Version 2 posted You are reading this latest preprint version Show more versions Abstract Background Adolescents living in residential youth care represent one of the most vulnerable groups within child and youth welfare systems. They frequently experience complex developmental challenges, including unstable family environments, traumatic experiences, and disrupted caregiving which may contribute to elevated rates of psychological distress, psychiatric disorders, and problematic cannabis use. Residential care staff report substantial burdens related to substance use among youth but have limited access to structured, evidence-based prevention tools. Existing prevention programs are largely school-based and not adapted to the organizational structures, routines, and relational dynamics of residential facilities. As a result, a substantial gap persists between youth welfare services and addiction prevention systems. Despite the clear need, systematically evaluated, target-group-specific prevention or early-intervention programs for adolescents in residential care remain scarce. This study aims to evaluate the feasibility and preliminary effectiveness of an adapted version of the evidence-based CAN Stop group program for reducing problematic cannabis use among adolescents in residential youth care. Methods/design This exploratory study uses a cluster-randomized controlled trial with two parallel arms: an intervention group receiving the adapted CAN Ju Stop program and a waitlist control group. Clusters—defined as residential care units—are randomized at the group level. Assessments take place in both groups at baseline (t 0 ), post-intervention (t 1 ) and six-month follow-up (t 2 ). Adolescents aged 12–21 years living in residential youth care are eligible with informed consent; exclusion criteria are acute psychosis or acute suicidal ideation. CAN Ju Stop consists of six weekly sessions delivered by trained residential care staff and focuses on motivational enhancement, harm reduction, and coping skills. The primary outcome is the continued abstinence and/or meaningful reduction of cannabis use in the past 30 days, measured by self-report; secondary outcomes include problematic use patterns, refusal self-efficacy, and future use intentions. Discussion Findings from this study will help inform the development and implementation of a future RCT, should the CAN Ju Stop prevention program be feasible in residential youth care. Trial registration : German Clinical Trials Register, DRKS-ID: DRKS00034167. Registered 13 May 2024, https://drks.de/search/en/trial/DRKS00034167 Residential youth care Adolescents Cannabis use Substance-use prevention Cluster-randomized controlled trial Harm reduction Early intervention Full Text Additional Declarations The authors declare potential competing interests as follows: CB and RT receive minor author revenues from the publication of the original CAN Stop manual from which the current CANJuStop intervention was developed. The other authors declare they have no conflict of interest. Supplementary Files SPIRIT2025editablechecklistarnaudetal.docx Cite Share Download PDF Status: Posted Version 2 posted You are reading this latest preprint version Show more versions 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. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8394115","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Study protocol","associatedPublications":[],"authors":[{"id":583183817,"identity":"bcb14dc7-6c9b-4b28-98da-a7feec742edd","order_by":0,"name":"Nicolas Arnaud","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAuUlEQVRIiWNgGAWjYBADxn4GNiDFRoqWmQ0ka9lwgFgt5gzMzz4X1ByW3XwjLfEBQ5kNYS2WDWzGs2ccO2y87UbaYQOGc2mEtRgcYDBm5mE7nLjtRnqbBGPbYWK0sH9m5vl3OHHzjPT2H4xt/4nRwmPMzNt2OHGDRNoxBsa2A0RoOcxTzMzbl24848yzZImEc8lEaDnevpmZ55u1bH97muGHD2V2hLUwMCNzEojQMApGwSgYBaOACAAA4kM3YFOJweQAAAAASUVORK5CYII=","orcid":"","institution":"University Medical Center Hamburg-Eppendorf (UKE)","correspondingAuthor":true,"prefix":"","firstName":"Nicolas","middleName":"","lastName":"Arnaud","suffix":""},{"id":583183818,"identity":"1a10f78c-0e8f-4d9f-8ae7-04e12f07ac3d","order_by":1,"name":"Anna-Lena Schulz","email":"","orcid":"","institution":"University Medical Center Hamburg-Eppendorf (UKE)","correspondingAuthor":false,"prefix":"","firstName":"Anna-Lena","middleName":"","lastName":"Schulz","suffix":""},{"id":583183819,"identity":"98090365-743d-4f27-a385-7e699c409d98","order_by":2,"name":"Christiane Baldus","email":"","orcid":"","institution":"University Medical Center Hamburg-Eppendorf (UKE)","correspondingAuthor":false,"prefix":"","firstName":"Christiane","middleName":"","lastName":"Baldus","suffix":""},{"id":583183820,"identity":"87ebcfd0-95ff-47d3-be69-54df84feb12f","order_by":3,"name":"Julian Harbs","email":"","orcid":"","institution":"University Medical Center Hamburg-Eppendorf (UKE)","correspondingAuthor":false,"prefix":"","firstName":"Julian","middleName":"","lastName":"Harbs","suffix":""},{"id":583183826,"identity":"1e7efd2f-a56d-4d0e-b891-c58555c4544f","order_by":4,"name":"Sabrina Kunze","email":"","orcid":"","institution":"University Medical Center Hamburg-Eppendorf (UKE)","correspondingAuthor":false,"prefix":"","firstName":"Sabrina","middleName":"","lastName":"Kunze","suffix":""},{"id":583183827,"identity":"c88f3dad-f1f6-4be6-b4ad-cb4375b5ae82","order_by":5,"name":"Rainer Thomasius","email":"","orcid":"","institution":"University Medical Center Hamburg-Eppendorf (UKE)","correspondingAuthor":false,"prefix":"","firstName":"Rainer","middleName":"","lastName":"Thomasius","suffix":""},{"id":583183828,"identity":"59074193-e79f-4e31-b3c3-3b2c4f138a09","order_by":6,"name":"Anne Daubmann","email":"","orcid":"","institution":"University Medical Center Hamburg-Eppendorf (UKE)","correspondingAuthor":false,"prefix":"","firstName":"Anne","middleName":"","lastName":"Daubmann","suffix":""},{"id":583183830,"identity":"1373b207-507f-4421-94c3-160c7c74bb40","order_by":7,"name":"Kerstin Paschke","email":"","orcid":"","institution":"University Medical Center Hamburg-Eppendorf (UKE)","correspondingAuthor":false,"prefix":"","firstName":"Kerstin","middleName":"","lastName":"Paschke","suffix":""}],"badges":[],"createdAt":"2025-12-18 10:09:42","currentVersionCode":2,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":true,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-8394115/v2","doiUrl":"https://doi.org/10.21203/rs.3.rs-8394115/v2","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":106961756,"identity":"a7e78d2d-a95d-4adc-9c0c-22a7e3a7650f","added_by":"auto","created_at":"2026-04-15 09:26:53","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":543435,"visible":true,"origin":"","legend":"","description":"","filename":"ArnaudetalPAFSv.03.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8394115/v2_covered_c97a8cce-47cd-4f29-9280-e171205704da.pdf"},{"id":106914275,"identity":"13761968-2688-4473-8114-65d392eb6389","added_by":"auto","created_at":"2026-04-14 17:35:31","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":34235,"visible":true,"origin":"","legend":"","description":"","filename":"SPIRIT2025editablechecklistarnaudetal.docx","url":"https://assets-eu.researchsquare.com/files/rs-8394115/v2/e62744938589284729803d6f.docx"}],"financialInterests":"The authors declare potential competing interests as follows: CB and RT receive minor author revenues from the publication of the original CAN Stop manual from which the current CANJuStop intervention was developed. 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","formattedTitle":"\u003cp\u003eIntroducing a group-based cannabis prevention program for adolescents in youth residential care in Germany (CAN\u003cem\u003eJu\u003c/em\u003eStop): Study protocol for an exploratory randomized controlled trial\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","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":"Residential youth care, Adolescents, Cannabis use, Substance-use prevention, Cluster-randomized controlled trial, Harm reduction, Early intervention","lastPublishedDoi":"10.21203/rs.3.rs-8394115/v2","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8394115/v2","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground \u003c/strong\u003eAdolescents living in residential youth care represent one of the most vulnerable groups within child and youth welfare systems. They frequently experience complex developmental challenges, including unstable family environments, traumatic experiences, and disrupted caregiving which may contribute to elevated rates of psychological distress, psychiatric disorders, and problematic cannabis use. Residential care staff report substantial burdens related to substance use among youth but have limited access to structured, evidence-based prevention tools. Existing prevention programs are largely school-based and not adapted to the organizational structures, routines, and relational dynamics of residential facilities. As a result, a substantial gap persists between youth welfare services and addiction prevention systems. Despite the clear need, systematically evaluated, target-group-specific prevention or early-intervention programs for adolescents in residential care remain scarce. This study aims to evaluate the feasibility and preliminary effectiveness of an adapted version of the evidence-based CAN Stop group program for reducing problematic cannabis use among adolescents in residential youth care.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods/design \u003c/strong\u003eThis exploratory study uses a cluster-randomized controlled trial with two parallel arms: an intervention group receiving the adapted CAN\u003cem\u003eJu\u003c/em\u003eStop program and a waitlist control group. Clusters—defined as residential care units—are randomized at the group level. Assessments take place in both groups at baseline (t\u003csub\u003e0\u003c/sub\u003e), post-intervention (t\u003csub\u003e1\u003c/sub\u003e) and six-month follow-up (t\u003csub\u003e2\u003c/sub\u003e). Adolescents aged 12–21 years living in residential youth care are eligible with informed consent; exclusion criteria are acute psychosis or acute suicidal ideation. CAN\u003cem\u003eJu\u003c/em\u003eStop consists of six weekly sessions delivered by trained residential care staff and focuses on motivational enhancement, harm reduction, and coping skills. The primary outcome is the continued abstinence and/or meaningful reduction of cannabis use in the past 30 days, measured by self-report; secondary outcomes include problematic use patterns, refusal self-efficacy, and future use intentions.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDiscussion \u003c/strong\u003eFindings from this study will help inform the development and implementation of a future RCT, should the CAN\u003cem\u003eJu\u003c/em\u003eStop prevention program be feasible in residential youth care.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial registration\u003c/strong\u003e: German Clinical Trials Register, DRKS-ID: DRKS00034167. 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