A Genetic Investigation of Sex Bias in the Prevalence of Attention-Deficit/Hyperactivity Disorder.

Biol Psychiatry
Authors
Keywords
Abstract

BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) shows substantial heritability and is two to seven times more common in male individuals than in female individuals. We examined two putative genetic mechanisms underlying this sex bias: sex-specific heterogeneity and higher burden of risk in female cases.

METHODS: We analyzed genome-wide autosomal common variants from the Psychiatric Genomics Consortium and iPSYCH Project (n = 20,183 cases, n = 35,191 controls) and Swedish population register data (n = 77,905 cases, n = 1,874,637 population controls).

RESULTS: Genetic correlation analyses using two methods suggested near complete sharing of common variant effects across sexes, with r estimates close to 1. Analyses of population data, however, indicated that female individuals with ADHD may be at especially high risk for certain comorbid developmental conditions (i.e., autism spectrum disorder and congenital malformations), potentially indicating some clinical and etiological heterogeneity. Polygenic risk score analysis did not support a higher burden of ADHD common risk variants in female cases (odds ratio [confidence interval] = 1.02 [0.98-1.06], p = .28). In contrast, epidemiological sibling analyses revealed that the siblings of female individuals with ADHD are at higher familial risk for ADHD than the siblings of affected male individuals (odds ratio [confidence interval] = 1.14 [1.11-1.18], p = 1.5E-15).

CONCLUSIONS: Overall, this study supports a greater familial burden of risk in female individuals with ADHD and some clinical and etiological heterogeneity, based on epidemiological analyses. However, molecular genetic analyses suggest that autosomal common variants largely do not explain the sex bias in ADHD prevalence.

Year of Publication
2018
Journal
Biol Psychiatry
Volume
83
Issue
12
Pages
1044-1053
Date Published
2018 06 15
ISSN
1873-2402
DOI
10.1016/j.biopsych.2017.11.026
PubMed ID
29325848
PubMed Central ID
PMC5992329
Links
Grant list
G1000632 / Medical Research Council / United Kingdom
R01 MH094469 / MH / NIMH NIH HHS / United States
U01 MH109536 / MH / NIMH NIH HHS / United States
U54 HD086984 / HD / NICHD NIH HHS / United States
R01 MH107649 / MH / NIMH NIH HHS / United States
Wellcome Trust / United Kingdom
MR/L010305/1 / Medical Research Council / United Kingdom
R44 HG006981 / HG / NHGRI NIH HHS / United States
106047 / Wellcome Trust / United Kingdom