Are we getting better at identifying and diagnosing neurodivergent girls and women? Insights into sex ratios and age of diagnosis from clinical population data in Scotland

Abstract

This study examined differences in referral and diagnosis based on sex recorded at birth (hereafter, ‘sex’), using case notes from 408 individuals diagnosed by 30 multidisciplinary teams across Scotland. Analyses focused on male-to-female ratios and median ages at referral and diagnosis across attention-deficit/hyperactivity disorder, autism and intellectual disability. The lifespan male-to-female ratio across all diagnoses was 1.31, varying by category and age. In autism, the male-to-female ratio was 2.21 for children under 10 years, but there were more females in adolescence (male-to female ratio=0.79) and adulthood (male-to-female ratio=0.94). Across the lifespan, combining all diagnoses, females were referred later (median ages: 14.4 vs 19.7 years; p<0.001) and diagnosed later (median ages: 15.2 vs 20.2 years; p<0.001), indicating a 5-year delay. Among autistic children and adolescents, females were referred later (median age: 7.5 vs 10.5years; p=0.002) and diagnosed later (median age: 9.3 vs 11.9years; p=0.003). However, no significant differences were found in age of referral or diagnosis for autistic adults. Overall, the results indicate partial equalisation of sex ratios across the lifespan, pronounced asymmetry in younger age groups, andconsistent delays in referral and diagnosis ages for females.