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 meta-analysis 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.