Initial cohort characteristics and protocol for SIGMA: An accelerated longitudinal study of environmental factors, inter- and intrapersonal processes, and mental health in adolescence

Background: Over half of all mental health conditions have their onset in adolescence. Large-scale epidemiological studies have identified relevant environmental risk factors for mental health problems. Yet, few have focused on potential mediating inter- and intrapersonal processes in daily life, hampering intervention development. Objectives: To investigate 1) the impact of environmental risk factors on changes in inter- and intrapersonal processes; 2) the impact of altered inter- and intrapersonal processes on the development of (sub)clinical mental health symptoms in adolescents and; 3) the extent to which changes in inter- and intrapersonal processes mediate the association between environmental risk factors and the mental health outcomes in adolescents. Methods: ‘SIGMA’ is an accelerated longitudinal study of adolescents aged 12 to 18 from across Flanders, Belgium. Using self-report questionnaires, experience sampling, an experimental task, and wearables, we are investigating the relationship between environmental risk factors (e.g. trauma, parenting), inter- and intrapersonal processes (e.g. real-life social interaction and interpersonal functioning) and mental health outcomes (e.g. psychopathology, self-harm) over time. Results: N= 1913 adolescents (63% female) aged 11 – 20, from 22 schools, participated. The range of educational trajectories within the sample was broadly representative of the Flemish general adolescent population. Conclusions: Our findings will enable us to answer fundamental questions about inter- and intrapersonal processes involved in the development and maintenance of poor mental health in adolescence. This includes insights regarding the role of daily-life social and cognitive-affective processes, gained by using experience sampling. The accelerated longitudinal design enables rapid insights into developmental and cohort effects.