Abstract
BACKGROUND: Attention Deficit Hyperactivity Disorder (ADHD) is commonly defined as a categorical diagnosis requiring clinically severe symptoms and impact on functioning. However, ADHD and other neurodevelopmental traits are also distributed continuously in the general population, where their impact on functioning is less clear. This study aimed to examine the association between ADHD impact and (a) ADHD traits, (b) co-occurring neurodevelopmental traits (autistic traits, reading ability, IQ, and pragmatic communication), and (c) genetic risk for ADHD. We also examined sex differences in these associations. METHODS: We identified 12,439 children with parent or teacher reports of ADHD at ages 8 and 11 in a UK birth cohort. We examined ADHD impact (i.e., in school, home, friendships, leisure activities, and distress) as an outcome of ADHD traits and other neurodevelopmental traits at each timepoint for each informant. Polygenic scores for ADHD were derived for each child and used to predict ADHD impact. Analyses controlled for child's age at completion of ADHD measures. We also stratified analyses by sex and tested for interactions with sex. RESULTS: ADHD traits were associated with ADHD impact across informants, ages, and sex (β = 0.46-0.64). There were stronger associations among males according to parents, but no sex differences according to teachers. In multivariable analyses, ADHD traits had the strongest association with impact, autistic traits and reading ability predicted parent-rated impact and pragmatic communication predicted teacher-rated impact. There was no evidence of an association between genetic risk for ADHD and ADHD impact when controlling for ADHD traits. CONCLUSIONS: ADHD and other neurodevelopmental traits were associated with ADHD impact in children from the general population. This reinforces the importance of inclusive environments for neurodivergent people. Clinicians and educators should consider the presence of impact and multiple neurodevelopmental difficulties when making decisions about support for all children.