Parental education level and ADHD diagnosis in childhood and adolescence: the moderating roles of gender, age, and family history of ADHD.

Low parental education has been suggested as a risk factor for attention-deficit hyperactivity disorder (ADHD), but the associations may differ by gender and age, as boys are diagnosed more often and earlier than girls. Parental education might also not predict offspring ADHD diagnosis similarly if parents themselves have ADHD. We examined how maternal and paternal education level predicts offspring ADHD diagnosis at ages 4-17 and whether these associations are modified by gender, age (4-12 vs. 13-17), and family history of ADHD (biological parent and/or full sibling vs. none). We used data on 419,152 individuals born in Finland between 1994 and 2003, identified ADHD diagnosis from national registers with first clinical diagnosis or ADHD medication purchase, and estimated incidence rate ratios (IRR) in Poisson regression. Compared to tertiary education, basic parental education predicted a higher than twofold likelihood of ADHD diagnosis in offspring (maternal IRR 2.17, 95% confidence interval 2.07-2.28; paternal 2.36, 2.26-2.48). The likelihood was about threefold in childhood and twofold or less in adolescence, and mostly similar for boys and girls. Among those with family history of ADHD, the associations were weaker in childhood (highest IRR 1.85, 1.30-2.64) and negligible in adolescence. These findings suggest that low parental education is more strongly associated with an increased likelihood of offspring ADHD diagnosis in childhood than adolescence and in families without an identified history of ADHD. Improving diagnostic processes may help ensure appropriate access to diagnosis and care at any age, irrespective of parental education level and family history of ADHD.