I came across this article today:

Unprecedented Reliable Data Proves That ADHD Is Overdiagnosed

So, to summarize, someone decided to go out and do research about the rates of ADHD diagnosis and test the common notion that ADHD is wildly overdiagnosed. They set out to determine whether therapists diagnose ADHD according to heuristic judgements (vague stereotypes of ADHD, basically) rather than established diagnostic criteria.

I have to say, I'm grateful that the reporters included the study's methodology:

"The researchers surveyed altogether 1,000 child and adolescent psychotherapists and psychiatrists across Germany. 473 participated in the study. They received one of four available case vignettes, and were asked to give a diagnoses and a recommendation for therapy. In three out of the four case vignettes, the described symptoms and circumstances did not fulfil ADHD criteria. Only one of the cases fulfilled ADHD criteria based strictly on the valid diagnostic criteria. In addition, the gender of the child was included as a variable resulting in eight different case vignettes."

The thing is, though, what's actually contained in those four case vignettes is important to the interpretation of this study. Presumably, at least some of the three "not ADHD" vignettes were chosen for the study because they did resemble ADHD prototypes. They were red herrings, in a sense.

But what about the opposite kinds of cases? What about cases that don't look like prototypical ADHD, but do fit the diagnostic criteria? I don't see how there could have been any room in this study's methodology to test those kinds of circumstances at all. That leaves us with no data about how often it happens that someone has ADHD, but gets told that they don't. So...if you're only testing prototypical cases, you cannot possibly be proving statistics of "over" diagnosis, only statistics of wrongful diagnosis...and even then, only one particular kind of wrongful diagnosis.

Think about it: you could just as easily craft a similar study that examined ONLY non-prototypical cases. These cases, if also judged heuristically, would probably result in similar numbers of inappropriate negative assessments of ADHD. Could we then conclude that overall, ADHD is wildly under-diagnosed by professionals? Of course not. For the same reason, it's bad logic to look at this study and conclude that ADHD is wildly over-diagnosed. All it really establishes is that ADHD is commonly misunderstood.

I think there are plenty of people living with ADHD who could have told you THAT.

Unfortunately, it's not surprising that the test didn't include any methods for testing wrongful negative diagnosis. I would imagine that the possibility simply never entered the researchers' minds simply because of the phenomenon that (seemingly) prompted the study in the first place: ADHD diagnosis is on the rise and has been for some time.

This fact, as many of us know, seems to be the sole basis for the belief that the disorder is over-diagnosed. If you don't stop and think about the logical problems with that conclusion and just how many things it irrationally assumes, I suppose there's no reason not to extend that lack of logical analysis into the idea that you don't have to test both sides of the circumstances.

  

The baseline assumption here is that misunderstanding and wrongful diagnostic practices with ADHD can ONLY lead to a rise in diagnosis. The only way this could be true is if you first assume that people want to be diagnosed with ADHD and thus, shop around and get second opinions until the trend of wrongful diagnosis (which, logically, could be wrong in either direction) gives them what they want.

And now...we have come to the heart of the matter. That judgemental accusation is plenty familiar, isn't it?

Honestly, I don't believe that anyone sympathetic to ADHD would have overlooked the need to test for improper negative diagnosis.

It is not good science.