The Young Ones, pre-post results of a transdiagnostic ACT-training for adolescents with Severe Mental Illness

Young adults with severe mental illness (SMI) often face significant barriers to accessing mental health care, including (self)-stigmatization, social withdrawal, and a lack of appropriate treatment programs. These challenges underscore the need for recovery-oriented interventions tailored to the developmental needs of this population. The aim of this study was to evaluate Acceptance and Commitment Therapy (ACT), with its focus on psychological flexibility and values-based action, for young adults with SMI. This pre-post pilot evaluation assessed the indications for feasibility, and preliminary outcomes of The Young Ones (TYO), an eight-week, ACT-based, transdiagnostic group intervention designed for young adults with SMI. Outcomes included personal recovery, functional impairment, psychological flexibility, and self-stigmatization. To evaluate change over time, we conducted separate Linear Mixed Models (LMM) for each outcome measure using an intention-to-treat (ITT) approach. Of 101 eligible participants, sixty-one individuals enrolled in the research, and 33 completed both pre- and post-measures (46% attrition). Significant improvements were observed in personal recovery and functional impairment. No significant changes were found for psychological flexibility or self-stigmatization. TYO appears feasible and acceptable for young adults with SMI, with promising indications of benefit in personal recovery and daily functioning. While dropout remains a concern, these preliminary findings support the need for a randomized controlled trial to rigorously evaluate the effectiveness of ACT-based group interventions for this population.