“What matters to you?”: A randomized controlled effectiveness trial, Using Systematic Idiographic Assessment as an intervention to Increase Adolescents’ perceived control of their mental health

Abstract Introduction Over the last decades, many Western countries have seen an increase in mental health difficulties in the adolescent population. Among Norwegian adolescents, internalizing symptoms are most prevalent, and 10%–38% of adolescents seek out primary health care services for mental health problems. This study examined whether an idiographic measure designed for adolescents called Assert, which uses variables individually selected by the adolescents, could improve user involvement, locus of control, mental health, and quality of life. Methods This study conducted a randomized controlled effectiveness trial using Assert in primary healthcare. A community sample of 150 Norwegian adolescents aged 12–23 years (M = 16.2; SD = 2.2) were randomized to the Assert or control group. Of the participants 27 (18%) were male. The adolescents and 52 counsellors from primary healthcare services responded to online questionnaires. Of the counselors, 92.8% were female and trained in the use of systematic idiographic assessment. Results Adolescents who used Assert scored significantly lower on external LoC, attributing less of their mental health improvement to chance, fate, or luck. However, the intervention showed no effect on the symptoms of mental health, QoL, or user involvement. Conclusions Using Assert in primary healthcare may enhance adolescents’ sense of being able to influence their life circumstances and mental health by allowing them more control of their treatment. However, this approach might not be successful in reducing symptoms.