Indirect associations between adolescent ADHD and/or oppositional defiant disorder symptoms and adult incomes: the mediating roles of education and co-occurring psychiatric disorders.

This longitudinal, population-based cohort study examines the direct and indirect associations between adolescent Attention-Deficit/Hyperactivity Disorder (ADHD) and/or Oppositional Defiant Disorder (ODD) symptoms and adult incomes. Moving beyond a simple direct link, our model explores how ADHD and/or ODD symptoms indirectly affect the accumulation of human, social, and health capital, which in turn may affect productivity and income. The population was drawn from members of the Northern Finland Birth Cohort 1986 (NFBC1986) who had ADHD and ODD symptoms assessed at age 16 using the Strengths and Weaknesses of ADHD Symptoms and Normal Behaviours (SWAN) scale. The results indicate a significant indirect negative effect of adolescent ADHD and ADHD + ODD symptoms on adult incomes. This effect was most pronounced in males with ADHD + ODD, who experienced a 25% income reduction via human capital (education) and an 18% reduction via health capital (presence of psychiatric disorders other than ADHD or ODD). Social capital did not mediate the association. The model was adjusted for work experience, white-collar status, marital status, parenthood, self-rated health, educational attainments of the participants' parents and family type during adolescence. Notably, no direct effect of adolescent ADHD and/or ODD symptoms on adult incomes was observed. These findings highlight the potential of educational and healthcare investments to reduce the income disparities associated with ADHD and ODD symptoms in the general population.