ADHD is a real disorder, but it is only one of many disorders that can affect attention. Most commonly, comorbid diagnoses are overlooked, or other disorders that affect attention are overlooked. Partly is the way ADHD is often tested.  A person who suspects they have ADHD will call for "an ADHD evaluation." The resulting evaluation is, from the start, targeted to a single disorder rather than a full evaluation.  When it turns out the attentional problem is really due to anxiety, hypomania, or some thought irregularity, the client or referral source is puzzled or disappointed.  They have come to get their ADHD diagnosis corroborated, and if the psychologist avers that the problem is due to a myriad of other possible disorders, their treatment with their provider is stymied. I corresponded for a while with Kieth Connors, who developed the idea of ADHD in this country and many of the popular tests. He told me that ADHD now is vastly overdiagnosed--this coming from the person who worked to get the notion of ADHD accepted in the scientific community.  Another problem with testing is that people with attentional issues of one sort or another will score high enough on the ADHD tests to justify a diagnosis. These reports can be churned out, But if treated only for ADHD, their level of functioning is always a tad lower than it could be otherwise had they been treated for the correct diagnosis.  Treatment for ADHD may enhance functioning somewhat, but there is always a gap between their functioning performance and their potential.  Pro bly the tendency of some testers to know only a few diagnoses lies at the root of the problem. With ut a background in inpatient care, or outpatient care, different ages, experience with neurological problems, and a diverse population, there is a lack of variegation in the diagnostician's menu of diagnosis. The  saying, "if all you have is a hammer, everything is a nail," really holds true.