Prevalence of attention deficit hyperactivity disorder in adults: Umbrella review of evidence generated across the globe

Background: Attention deficit hyperactivity disorder (ADHD) is a class of neurodevelopmental disorders which is commonly diagnosed in school-age children, but it can occur in any age group. To provide a robust synthesis of published evidence on the prevalence of ADHD in adults, we conducted an umbrella review of systematic reviews and meta-analyses. Methods: The review was guided by preferred reporting items for systematic review and meta-analysis (PRISMA). We searched PsychINFO, Web of Science, PubMed, and Scopus to retrieve pertinent studies. The review protocol was registered with PROSPERO (CRD42023389704). A Measurement Tool to Assess Systematic Reviews (AMSTAR) was used to assess the quality of the included studies. A random-effects model was used to perform a meta-analysis. Results: Five systematic reviews and meta-analyses (57 unique primary studies) with data on 21,142,129 adult participants were eligible for inclusion in this umbrella review. Inverse variance weighted random effect metaanalysis of these studies indicated that the pooled prevalence of ADHD in adults was 3.10% (95%CI 2.60-3.60%). ADHD-I (the inattentive type of ADHD) remained the commonest type of ADHD, followed by ADHD-HI (the hyperactive type) and ADHD-C (the combined type). Conclusion: The results indicate that ADHD is relatively high in adults, with ADHD-I remaining the most common subtype. Attention should be given to preventing, reducing, identifying, and managing ADHD in adults.