Academic achievement and socio-demographic differences in ADHD diagnosis: a population-based study of Swedish compulsory school pupils.

BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) is more commonly diagnosed among boys, children with lower socio-economic status (SES), and native-born compared with immigrant children. ADHD can strongly impair academic achievement, and impaired academic functioning can also trigger diagnostic referral. The aim of this paper was to investigate how socio-demographic differences in ADHD diagnosis change when differences in academic achievement are taken into account. METHODS: Population-based cross-sectional study using linked national registers, comprising 296,380 pupils graduating from Swedish compulsory school (grade 9, age 16) between 2015 and 2017. ADHD was defined using specialist diagnoses and dispensed ADHD medication. Academic achievement was measured by compulsory school-leaving grades. Logistic regression models were estimated with and without adjustment for achievement, and estimates were transformed into marginal effects and predicted probabilities. RESULTS: Before adjustment for achievement, boys had a higher probability of ADHD diagnosis than girls, pupils with tertiary-educated parents had a lower probability than those with compulsory-educated parents, and immigrant pupils had substantially lower probability than native pupils. Adjustment for achievement reduced the gender gap by approximately two thirds, reversed the SES gradient such that pupils with tertiary-educated parents had the highest probability, and slightly widened the native-immigrant gap. When accounting for differential timing of diagnosis, the gender gap even reversed, with a higher probability among girls than among boys. CONCLUSIONS: The findings underscore the need to consider academic achievement when interpreting socio-demographic patterns in ADHD diagnosis, and suggest that some groups may face barriers to diagnosis even when their level of academic impairment is comparable to that of more frequently diagnosed groups.