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How Many Mental Health Patients Have ADHD?

Like any self-respecting clickbait artist, I’ve put a question in the title of this blog post. So let me get right to answering it.

ADHDHow many people who seek out mental health treatment have ADHD? The short answer is: possibly a lot more than we actually diagnose.

The long answer is: it’s complicated. It’s complicated because diagnosing ADHD is complicated, and diagnosing ADHD is especially complicated when there are other mental health conditions involved given that many conditions have symptoms that overlap with those of ADHD.

Still, just because people have, for example, an anxiety disorder, doesn’t mean they don’t also have ADHD. In fact, ADHD often comes with companions. Unfortunately, because ADHD isn’t always a disorder that steals the limelight, people who have ADHD + 1 often end up with a diagnosis for the +1 and not the ADHD.

Recently, a team of researchers in Ireland, decided to screen a series of patients showing up at mental health clinics in a particular area to see how many had symptoms of ADHD. Altogether, they collected data on 634 patients.

For each patient, the research administered two screening questionnaires. For each questionnaire, about a third of the people surveyed were above the threshold for having ADHD. On top of that, one in five people met the criteria for ADHD on both questionnaires.

So because these people were receiving treatment at a mental health clinic, they were probably already diagnosed, right? Just kidding. Only 2.3 percent of them had received a diagnosis.

Of course, without a more comprehensive evaluation, it’s possible that not all these people had ADHD. It could be that symptoms of other mental health conditions led them to have high scores on the screening questionnaires. Still, it seems likely that at least some of them did indeed have undiagnosed ADHD.

This study suggests that a lot of people who receive treatment for mental health conditions other than ADHD also have ADHD, and that the ADHD diagnosis is being frequently missed. It’s not hard to do an initial screening and see if a more thorough evaluation is warranted. Although it’s too early to say generally that one in five mental health patients has ADHD, it’s not too early to say that looking into the possibility as part of the diagnostic process will make mental health treatment in general more effective.

Image: Flickr/Leo Brunvoll

How Many Mental Health Patients Have ADHD?

Neil Petersen

Neil Petersen writes regularly on education, learning disabilities and technology. He received his B.A. in 2014 and was diagnosed with ADHD at the beginning of his college studies. Neil also works for a music education non-profit and hopes to help create an education system that can better serve students with ADHD.

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APA Reference
Petersen, N. (2018). How Many Mental Health Patients Have ADHD?. Psych Central. Retrieved on September 16, 2019, from


Last updated: 22 Aug 2018
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