3 - (SYM 34) Does CBT for Adult ADHD Remain Effective Long-term? Evidence from an 8-year Follow-up

Background: Despite growing evidence for short-term efficacy of cognitive-behavioral therapy (CBT) in adults with ADHD, long-term outcomes remain largely unknown, with the longest published follow-up being only 1.5 years. Time management difficulties represent a particularly impairing characteristic of adult ADHD, predicting key occupational outcomes.

Objective: To evaluate 8-year outcomes from a randomized controlled trial of group CBT targeting time management in adults with ADHD, and to explore whether digital booster interventions help maintain treatment gains.

Methods: Japanese adults with ADHD (N=48) were originally randomized to eight-week group CBT (n=24) or treatment-as-usual (n=24). Five years post-baseline, CBT participants were offered an optional digital booster intervention (n=9 accepted). Outcomes included ADHD symptoms (CAARS eight subscales), depression (BDI-II), anxiety (STAI-S), functional impairment (SDS three domains), and Time Management Scale. CAARS Inattention/Memory was the primary outcome. Linear mixed models examined group×time interactions, with sensitivity analyses using multiple imputation and Bayesian models with informative priors.

Results: Retention at 8-year follow-up was 50% (24/48). In intention-to-treat analysis, participants randomized to CBT showed lower inattention than TAU at 8 years (d = -0.65, p = .038), though not robust to multiple imputation (p = .48). Exploratory three-group comparison revealed CBT+booster participants maintained improvements from post-intervention through 8-year follow-up, while CBT-only participants deteriorated to near-baseline levels. CBT+booster showed significantly lower inattention than both TAU (d = -1.60) and CBT-only (d = -2.04) at 8 years, though not robust to multiple imputation. Within-subject analysis showed symptom reductions became significant again following sustained booster engagement (d = -1.14 to -1.88).

Conclusions: Digital booster interventions may help maintain long-term CBT benefits in adult ADHD. However, high attrition, small sample size, and non-robust findings under multiple imputation highlight substantial methodological challenges requiring cautious interpretation.