Prevalence of ADHD

If you read up on ADHD, you’ll find all sorts of often conflicting information. That’s why I like Russell Barkley. He’s one of the best known researchers on ADHD. He has published 15 books, more than 200 scientific articles, and 7 videos on ADHD and related topics. The 3rd edition of his Attention-Deficit Hyperactivity Disorder: A Handbook for Diagnosis and Treatment just came out. It’s a handbook for clinicians, those people who diagnose and treat ADHD. Since I like science, and like knowing what I’m talking about, I got myself a copy. Leafing through it, I was only mildly astonished to read that there have been literally thousands of studies on ADHD. Barkley estimates the current number to be on the order of 6,000! And I swear, he and his contributors cite a large percentage of them in this 770-page reference book.

Prevalence was the first thing I wanted to get the latest information on. Just how prevalent is ADHD? In kids? In adults? Turns out, some of the difference in numbers we see bandied about can be attributed to using different definitions for what constitutes ADHD. The current definition of ADHD is what’s in the DSM-IV. By that definition, Barkley cites 7.4% of kids in this country ages 5-19 have ADHD. Another study by the CDC that came out in 2005 reveals that 7.8% of kids in this country ages 7-17 are diagnosed with ADHD (you can see a summary of that study’s results here).

For adults, a recent NIMH-funded survey tracking the prevalence of ADHD symptoms found that an estimated 4.4% of adults ages 18-44 in the United States experience symptoms and some disability. The survey is known as the National Comorbidity Survey Replication (NCS-R) and is part of a series of tracking surveys supported by NIMH and conducted by researchers at Harvard Medical School to assess the state of mental health of the nation. The rest of the summary of this study’s results is available here.

So, using current definitions and the most recent research, I have an answer regarding prevalence: 7.4%-7.8% of kids and 4.4% of adults in this country have ADHD.

(BTW, It’s useful to remember that these are a nation-wide averages. Your local results might vary!)