Childhood ADHD and autism spectrum disorder difficulties: exploring the impact of copy number variants on young adult outcomes.

Rare copy number variants (CNVs; deleted/duplicated DNA segments) are associated with childhood attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). It is unknown whether carrying a CNV moderates the effect of ADHD/ASD on adult outcomes. In a UK population-based cohort, the Avon Longitudinal Study of Parents and Children, ADHD and ASD difficulties at ages 7-16 years were defined categorically. Outcomes included: General Certificate of Secondary Education non-attainment; depression at ages 18 and 24; functioning at age 25; not in education, employment or training; and receiving state benefits at age 25. Logistic regressions were used to assess associations between ADHD/ASD and outcomes, and to test CNVs as moderators. Multiple imputation was used to account for data missingness. We did not find strong evidence of CNVs moderating the effect of ADHD or ASD on young adult outcomes. However, confidence intervals for the moderating effect were wide, so further research in larger clinical samples is necessary.