Reciprocal relations between ADHD and risky behavior in adolescence: a between and within-person longitudinal analysis

Background: The present study sought to extend the existing knowledge on the relationship between risky behavior and ADHD by studying transactions between these two variables within participants and across various time scales. Methods: Participants were 281 adolescents (170 girls), age 13–18 years old (M = 14.8, SD = 1.3), and 1 of their parents. Risky behavior and ADHD symptoms measurements were taken at varying time intervals: annually, 4-monthly, and weekly. Random Intercepts Cross-Lagged panel modeling (RI-CLPM) was used to examine longitudinal bidirectional associations between risky behavior and ADHD symptoms. Results: At the between-person level, positive associations between risky behavior and ADHD symptoms were found in all time scales. At the within-person level, according to adolescents' reports, ADHD symptoms did not predict subsequent fluctuations in adolescents' risky behavior, though according to parental reports on adolescents' risky behaviors, a cross-lagged effect of risky behaviors on ADHD symptoms was evident in the annual time scale. Conclusions: Between-person relations between ADHD and risky behavior were established, suggesting an underlying common factor. Within-person relations were suggested only in parent reports and specific time scales. Our research underscores the critical need to differentiate between inter-individual and intra-individual effects when investigating the interplay between ADHD and risky behavior over time.