This study used modelled estimates from the Global Burden of Disease project. It looked at people under 20 years old across 204 countries and territories, from young children through teenagers aged 15 to 19. No individual people were examined directly. The numbers come from a statistical model built on earlier prevalence studies, so both children and adolescents are covered.
The model estimated that in 2021 about 46.9 million young people had ADHD (46,890,733). That works out to a prevalence rate of 1.78%. Boys were affected more often than girls (2.52% versus 0.99%), and this pattern held in every world region. ADHD was more common in wealthier, more developed countries, and it was highest in Australia (5.62%). Prevalence peaked at ages 10 to 14.
Compared with 1990, the rate of ADHD in under-20s was slightly lower in 2021 (down 6%), and the rate of new cases was also lower (down 5.81%). Even so, the total number of cases rose over the same period (up 9.7%).
The authors caution that these figures are likely too low. The search behind the model was not updated after 2017, some countries had no data, and several parts of the burden were left out of the calculation. They conclude that the real numbers may be higher.
Source: Samuele Cortese, Min Seo Kim, Jong Hoon Han, et al.. Incidence, prevalence, and global burden of attention-deficit/hyperactivity disorder from 1990 to 2021 across 204 countries in individuals under age 20: data, with critical appraisal, from the 2021 Global Burden of Disease study. Molecular Psychiatry (2026). doi:10.1038/s41380-026-03683-4