Objective: This study aimed to examine whether parent–child interaction therapy (PCIT), compared with other therapy modalities, was associated with differences in substance use and psychiatric outcomes in a cohort of children with attention-deficit/hyperactivity disorder (ADHD). Methods: This retrospective cohort study was conducted using medical record data from the Rochester Epidemiology Project (REP). The sample included 643 children aged ≤7 years who were diagnosed with ADHD and received either stimulant or nonstimulant medication, along with psychosocial therapy. Participants were categorized into two groups: those who documented exposure to PCIT versus other therapy modalities such as behavioral management, play therapy, cognitive behavioral therapy, parent management training, occupational therapy, speech therapy, parenting class, applied behavior analysis, and social skills training. Conditional logistic regression models were used to examine differences in baseline characteristics and outcomes between the two treatment groups. Results: Individuals in the PCIT group were more likely to have private insurance (66% vs. 57%; p = 0.016) and to fall into higher socioeconomic status quartiles ( p = 0.024) at baseline. PCIT recipients also had a higher prevalence of emotional and behavioral disturbances at baseline (40% vs. 25%; p < 0.001). The median age of the participants at follow-up was 19.6 years, indicating a median follow-up period of approximately 13 years from the initiation of treatment. At follow-up, the PCIT group demonstrated higher rates of problematic alcohol (24% vs. 17%; HR = 1.50, 95% CI: 1.02, 2.20; p = 0.038) and cannabis use (25% vs. 18%; HR = 1.48, 95% CI: 1.03, 2.15; p = 0.037). However, after controlling for covariates in the adjusted model, no statistically significant differences emerged between the groups across any substance use outcome. No significant differences were observed in other psychiatric diagnoses or mental health service utilization. Conclusions: Findings indicate that individuals who documented exposure to PCIT demonstrated elevated rates of alcohol and cannabis use in young adulthood, but had no other differences in psychiatric outcomes. While this aligns with prior literature reporting increased substance use risk in ADHD populations, our study cannot confirm this association relative to non-ADHD controls because such a comparison was not included. These associations likely reflect underlying differences in clinical severity and clinical comorbidities at baseline, rather than a direct effect of PCIT. Further investigation is warranted to determine the treatment effects based on baseline risk factors.
Price et al. (2026) studied this question.