Objective: Despite an emergence of psychosocial treatments for adolescent ADHD, their long-term effects are unknown.
Method: We examine four-year outcomes of a randomized controlled trial (N = 218) comparing high-intensity (HI; 412 h, $4,373 per participant) versus low-intensity (LI; 24 h, $97 per participant) skills-based summer intervention delivered to adolescents with ADHD at two secondary school transitions (6th/9th grade). Quantitative and qualitative analyses evaluated group×time and group×grade×time effects on 4-year outcomes.
Results: Relative to LI, a single dose of HI had modest but lasting effects on teen organization skills (d =.40) and ADHD symptoms (9th grade only: d =.27 to.31) at 4-year follow-up. There was no long-term incremental effect of HI (vs. LI) for parent-teen conflict, GPA, or parent use of contingency management. Treatment appeared most effective when delivered to older adolescents (i.e., 9th versus 6th grade), suggesting the long-term impact of ADHD treatment may increase with age. Qualitative data corroborated that the primary long-term benefit of HI (vs. LI) treatment was to organization skills; many of the remaining perceived benefits were to parent and teen psychological variables (i.e., increased self-esteem, self-awareness, parental optimism). HI offered no incremental benefit to long-term educational or clinical service utilization or costs.
Conclusions: Modest therapeutic benefits of adolescent ADHD treatment are maintained long term. However, HI treatment did not impact outcomes that could defray the intervention's high costs ($4,373) compared to LI treatment ($97).