HealthDay News  — About 7% of children worldwide have attention-deficit/hyperactivity disorder (ADHD), new research concludes.

This estimate — which differs significantly from other recent appraisals — is based on data from 175 prior studies conducted over nearly four decades.

The approximation could help public health officials determine whether ADHD is overdiagnosed or underdiagnosed in their nation, state or community, said lead author Rae Thomas, PhD, of Bond University in Australia.

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The estimate comes in lower than the latest data from the U.S. Centers for Disease Control and Prevention, which reports that 11% of U.S. school-age children had been diagnosed with ADHD by 2011.

However, it is double a worldwide ADHD estimate of 3.4% published in the Journal of Child Psychology and Psychiatry earlier this year, in a study that used very different methods, Thomas noted.

In the new study, published online in Pediatrics, the researchers pored over decades’ worth of research on ADHD and came up with 175 studies containing 179 estimates of ADHD prevalence.

When pooled together, the combined results contained data on more than 1 million children over a period of 36 years. The studies took place in North America and Europe.

All that data added up to a worldwide ADHD estimate of 7.2%, with a range running from 6.7% to 7.8%, according to the report.

Thomas noted that the estimate did vary between versions of the DSM — studies based on the DSM-IV had an average prevalence of 7.7%, while the DSM-III-based studies estimated 5.6% and the DSM-IIIR estimated 4.7%.

The included studies also varied widely in their estimates of ADHD, from a low of 0.2% to a high of 34%, Thomas said.


Thomas R, et al. Prevalence of Attention-Deficit/Hyperactivity Disorder: A Systematic Review and Meta-analysis. Pediatrics. 2015; doi: 10.1542/peds.2014-3482.