Understanding ADHD Diagnosis Rates and Honing Screening Strategies

Recent studies have shown conflicting findings that attention-deficit/hyperactivity disorder (ADHD) is both underdiagnosed and overdiagnosed across the United States. Combined with various anecdotal evidence from friends and family whose ADHD may have been missed or wrongfully diagnosed by clinicians paints a confusing picture of what the scope of ADHD diagnosis actually looks like.

Vladimir Maletic, MD, MS, clinical professor of psychiatry at the University of South Carolina School of Medicine in Greenville, South Carolina, and Psych Congress Network ADHD section editor, and Meagan Thistle, Managing Editor of Psych Congress Network, discuss these recent studies, whether or not ADHD is truly under or overdiagnosed, and what clinicians can do to better screen for the disorder.

Read the Transcript:

Meagan Thistle: Hi, Psych Congress Network. Thank you so much for joining us today. I am your managing editor, Meagan Thistle, and I'm here today with Dr Vladimir Maletic. If you'd like to introduce yourself.

Dr Vladimir Maletic: Yes, Meagan, and thank you for having me. My name is Vladimir Maletic and I'm a clinical professor of psychiatry at the University of South Carolina School of Medicine in Greenville, South Carolina.

Thistle: Well, thank you so much again for joining us today. Today, we will be talking about whether ADHD is underdiagnosed or overdiagnosed. I know this is a topic that you are very passionate about so I'm very excited to discuss this with you today. My first question for you is, could you discuss some of the misconceptions surrounding the rates of ADHD diagnosis, and what does the literature say about the rates children and adults are diagnosed with ADHD?

Dr Maletic: Meagan, it's a fascinating topic, but it's also a topic that has a high degree of clinical relevance. Unfortunately, when it comes to the question that you just asked, is ADHD over or underdiagnosed, there are many more opinions than well-designed studies. Sadly enough, a lot of it is speculation. A lot of it was prompted by a study that was published a couple of years ago by colleagues. In this study, they indicated that ADHD, at least in the childhood adolescent population, was significantly overdiagnosed.

Well, it is mostly based on the fact that the percentage of patients who have had ADHD in this age category has doubled over the course of 20 years. There is probably no arguing with that, but the fact that it has doubled doesn't mean necessarily the diagnosis is erroneous. If we're looking at what those percentages are, in terms of child and adolescent population, the prevalence of ADHD in the late '90s was somewhere about 6 to 8%. Many times in the literature, one quotes a number of 7.5%. I guess it's somewhere in the middle. 2018 and more recent years, that number has grown to 16%. We are very close to saying every sixth child and adolescent in the United States has ADHD. Indeed, it is a very substantial increase in numbers.

What might it reflect? Well, we have to remember that, in the meantime, the criteria have changed. The age related to the onset of symptoms, it was, in the past, 7 or under, and now it has changed to 12. The age limit has changed quite a bit. The other part is in how our data is collected, and there you will see great heterogeneity. Some of the data are collected using structured interviews. Some of the data took into account teacher reports and parental reports. Also, looking at the concordance between these 2, I think these are higher-quality data. Unfortunately, what we don't have a great degree of insight is the severity of symptom presentation. It's more present or not. The other is the degree of functional impairment. In some of the studies, they looked at functional impairment in 2 different settings and in some of the studies they looked at 1 setting. But the bottom line, in even the most recent data, these are data that have been generated within last 2 years.

In the United States, how likely you are to have ADHD depends on where you live. It's a little bit shocking, but in various states in the United States, the prevalence goes between 6 and 16%. There are dramatic geographic differences. Gender is very important because the numbers again vary. In some instances, it is about 60% more diagnosed in males versus females. In other studies, it's a threefold difference. Now, granted that there are important neurobiological differences, and this is where we are actually close to precise science. When it comes to norepinephrine signaling in the female brain versus the male brain, women will have approximately 20% more norepinephrine neurons emanating from each locus coeruleus. And then, the branching arborization of norepinephrine fibers in female brains is substantially greater than in male brains. When it comes to stimulated dopamine release, and this is based on some of the preclinical studies, there's about 25% higher dopamine release in female brains than in male brains.

When it comes to ADHD, I hate to put it this way, but it appears that women have a distinct biological advantage. It may be, number 1, that women are better at disguising their symptoms. I think disguising may not be appropriate, I would say effectively compensating. The other part may be that what attracts our attention are disruptive behaviors. Girls, at least in the past, would be less likely to engage in some of these disruptive behaviors than males would be. It doesn't mean that they had no symptoms or that the symptoms did not interfere with their functioning and quality of life. It's just, by virtue of not being disruptive, they remained undiagnosed.

Again, there are biological differences. There are also differences in terms of what attracts attention, and they may translate into these very large discrepancies. I think this is something that requires greater research. The other part that is quite interesting is 'do we have some literature indicating that there is a substantial number of individuals who have ADHD who are untreated?' I would say there we have great discrepancies as well. There are some studies that will say about 20% of people who have ADHD, and this is especially true in adult categories, are properly diagnosed and treated. 20%, 1 in 5.

There are other studies that are saying that it is very different, that the majority, two-thirds, of individuals who have adult ADHD are properly diagnosed and treated. In terms of what kind of treatment they're receiving, also we see a great degree of scatter. When it comes to pharmacologic treatment, it is 60 to 80% are receiving pharmacologic treatment. When it comes to psychotherapy, it is again somewhere between 40 to 60% receiving psychotherapy. Again, data are not consistent and that is something that makes it very problematic. But I would say that it's possible that ADHD is both under and over-diagnosed. That many times, individuals who have milder categories, it's hard to objectify the degree of functional impairment. If it is mild, they wouldn't necessarily require any pharmacologic intervention.

Behavioral interventions, especially in children, would be appropriate. American Academy of Child Psychiatry actually suggests that children in this category between 4 and 6 years are initially treated with behavioral therapy, as opposed to 7 and above where pharmacotherapy is actually first-line treatment. There's a lot of inconsistency in terms of the clinical approach, in terms of how diagnosis is made, but also in what are outcomes once the diagnosis is made in terms of the treatment approaches.

Thistle: It sounds like there's a lot to navigate when it comes to research. It depends on gender, it depends on geographic location, stage of life. That is a lot for clinicians to navigate so thank you for putting that into a succinct summary. Going off of that screening, in those situations where it might be underdiagnosed or even misdiagnosed, what can clinicians do to better screen for ADHD in both pediatric patients and then in their adult patients?

Dr Maletic: Here would be few things that I would suggest. In child and adolescent patients, we do want to go through all the symptoms that are involved in DSM-5 criteria. We want to make sure that formal criteria are met before we make the diagnosis. It is good to have information both from parents and also from teachers. It is good to have an individual interview with the child. Sometimes this is more confirmatory, but there are some objective tests that can help us. Tests of variants of attention. Conners CPT, continuous performance tests. Again, these are not diagnostic, but they're more confirmatory tests if we are not quite certain about the diagnosis.

Carefully map if there are functional impairments and in which settings, obtain data from teachers and parents and, if we need to, some objective studies that would provide supportive evidence. Those would be some of the important aspects of diagnosis in my mind, and definitely spending time in the room with the child and in the room with the child and parent, seeing if the child is hyperactive or being disruptive, how does the parent respond? Understanding the familial setting in which these symptoms occur because familial dynamic can definitely impact diagnosis. Those are some of the things that I would suggest. And then, use screeners because they cannot make the diagnosis, but they can help focus our discussion.

Vladimir Maletic, MD, MS, is a clinical professor of psychiatry and behavioral science at the University of South Carolina School of Medicine in Greenville, and a consulting associate in the Division of Child and Adolescent Psychiatry, Department of Psychiatry, at Duke University in Durham, North Carolina. Dr Maletic received his medical degree in 1981 and his master’s degree in neurobiology in 1985, both from the University of Belgrade in Yugoslavia. He went on to complete a residency in psychiatry at the Medical College of Wisconsin in Milwaukee, followed by a residency in child and adolescent psychiatry at Duke University.