(PS6-85) Moderators of Dose-response Relationships in School-based Treatment for Adolescents with ADHD

High school students with ADHD experience significant difficulties in academic and social-emotional domains (Hinshaw & Becker, 2020). Fortunately, school-based training interventions such as the Challenging Horizons Program (CHP) demonstrate promising outcomes among secondary students with ADHD at post-treatment (e.g., improvements in organizational and social skills; DuPaul et al., 2021; Evans et al., 2023), 6-mo follow-up (e.g., stabilization of GPAs; Evans et al., 2016), and 5-year follow-up (e.g., lower rates of job termination; Morse et al., 2023). Researchers have also identified thresholds for session attendance (i.e., > 30) that yield maximum benefit across similar outcomes (Margherio et al., 2023). However, variables related to associations between CHP session attendance (i.e., dosage) and treatment outcomes remain unclear. This study examined adolescent characteristics as moderators of relationships between high school CHP session attendance and academic and social-emotional outcomes.

Ninety-two 9­^th-11^th grade students with ADHD participated in the CHP. The CHP is a multicomponent training intervention that targets academic, social, and behavioral skills through repeated practice with performance feedback in twice weekly sessions across one academic year. Outcome measures included parent-completed Children’s Organizational Skills Scale (COSS; Abikoff & Gallagher, 2008) and Difficulties in Emotion Regulation Scale (DERS; Gratz & Roemer, 2004), adolescent-completed Social Skills Improvement System (SSIS; Gresham et al., 2011), and GPA at baseline, post-treatment, and 6-mo follow-up. Moderator variables included adolescents’ cognitive ability, treatment engagement (i.e., sum of coach ratings of student participation/effort in CHP activities at mid- and post-treatment), working alliance (i.e., WA; total scores on the adolescent-completed Working Alliance Inventory at mid-treatment; Hatcher & Gillaspy, 2006), and comorbid oppositional defiant disorder (ODD). Continuous moderator variables (i.e., IQ, treatment engagement, WA) were dichotomized via median splits. Moderation analyses using PROCESS macro version 4.2 (Hayes, 2022) were conducted to examine moderators in relationships between total number of CHP sessions attended and treatment outcomes (i.e., COSS, GPA, DERS, SSIS).

Adolescents rated as less engaged exhibited greater response on post-treatment SSIS (ꞵ = -1.30,  p = .024) and GPA (ꞵ = -1.21, p </em>= .013) as their session attendance increased. Conversely, WA did not moderate dose-response relationships on any outcome measure. Participants with lower IQs (ꞵ = -1.28, p </em>= .038) and comorbid ODD (ꞵ = -1.82, p </em>= .016) demonstrated steeper declines in COSS scores as dosage increased. There was also a positive dose-response relationship for post-treatment GPA among those with lower IQs (ꞵ = -1.58, p </em>= .002). Taken together, these results suggest that adolescents exhibiting greater levels of risk (i.e., less engaged with treatment, lower IQ, comorbid ODD) benefit most from frequent contact with their CHP coach. Assessment of risk factors may inform practitioners regarding which students’ attendance in the CHP should be prioritized in resource-constrained school mental health settings.