Male to female ratios in autism spectrum disorders by age, intellectual disability and attention‐deficit/hyperactivity disorder

2021/09/08 by Maj‐Britt Posserud, Berit Skretting Solberg, Anders Engeland +2 · 132 citations
Biochemistry, Genetics and Molecular Biology · Medicine · Neuroscience · Psychology · Social Sciences · #Attention deficit hyperactivity disorder #Autism #Autism Spectrum Disorder Research #Autism spectrum disorder #Comorbidity #Demographic Trends and Gender Preferences #Gerontology #Intellectual disability #Medicine #Pediatrics #Population #Psychiatry #Psychology #Sexual Differentiation and Disorders #Young adult

paper · pdf · doi:10.1111/acps.13368

published in Acta Psychiatrica Scandinavica 144(6), 635-646 (Wiley)

openalex publication_date 2021/09/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

OBJECTIVE: To examine the gender distribution in ASD in adults compared with children and the impact of comorbid intellectual disability (ID) and attention-deficit/hyperactivity disorder (ADHD) on the male to female ratio (MFR). METHODS: We estimated the MFR and the male prevalence ratio (PR) for ASD in adults and children using the Medical Birth Registry of Norway, including all individuals born during 1967-2011. We examined variation with age, comorbid ID and ADHD as defined by diagnoses in the Norwegian Patient Registry during 2008-2015 and/or a dispensed prescription for ADHD medication. RESULTS: The sample included 1,701,206 adults and 804,146 children, including 8,995 (0.5%) adults and 8,056 (1.0%) children with ASD, 53,822 (3.2%) adults and 26,967 (3.4%) children with ADHD and 9,178 (0.5%) adults and 5,038 (0.6%) children with ID. The MFR for ASD was 3.67 in children and 2.57 in adults, corresponding to a male PR in ASD of 1.54 (95% CI 1.53-1.56) and 1.41 (1.39-1.24), respectively. Comorbid ID decreased the MFR and the male PR in both adults and children, whereas comorbid ADHD significantly increased the male PR in children. The MFR and the population prevalence of ASD, ADHD and ID decreased from children to younger adults and yet further to older adults. CONCLUSION: We found a lower MFR and male PR in adults than in children. Findings suggest the strong male predominance seen in childhood/clinical studies of ASD diminishes in adult samples, possibly reflecting the influence of non-aetiological factors such as later diagnosis in females, diagnostic biases and diagnostic trends.

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