Antecedents and outcomes of a late attention deficit hyperactivity disorder (ADHD) diagnosis in females

Females receive an attention deficit hyperactivity disorder (ADHD) diagnosis at an older age than males. We examined the antecedents and outcomes of later (age 12+) diagnosis in females using data from a Welsh nation-wide electronic cohort of 13,593 individuals (N=2,680 (19.7%) females) with ADHD and 578,793 individuals (N=286,734 (49.5%) females) without ADHD. We compared females with later diagnoses (ages 12–25) to those with earlier, timely diagnoses (ages 5–11) and no diagnosis, in terms of childhood (ages 5–11) antecedents and adolescent/adult (ages 12–25) outcomes. We also tested for sex differences. Females with later diagnosed ADHD used more adolescent/adult healthcare services and had worse mental health, educational and socioeconomic outcomes than females diagnosed earlier. Health and educational difficulties were already evident in childhood in this group. Many outcomes were exacerbated in females compared to males. Timely childhood ADHD diagnosis is necessary to mitigate later risks, especially for females.