Overview of ADHD

Andrew J. Cutler, MD: There are several types of attention deficit hyperactivity disorder, or ADHD. According to the DSM-5 [Diagnostic and Statistical Manual of Mental Disorders, 5th edition] criteria, there are 2 categories of symptoms that we look at. The 2 categories are inattention and hyperactivity/impulsivity. There are 9 symptoms in each of these categories.

If you are a child under age 17, you need to have at least 6 of 9 symptoms from 1 or both categories to meet the criteria for diagnosis. If you’re an adult, aged 17 and above, the threshold drops to needing to meet only 5 of the criteria for 1 or both categories. The type of ADHD depends on whether you meet the criteria for 1 or both categories of symptoms.

In DSM-5, instead of calling it types of ADHD they changed it to presentations of ADHD. The most common presentation is called the combined presentation, and that would be somebody meeting the threshold of 5 or 6 symptoms from both of those categories. The next most common presentation is called the predominately inattentive presentation, and that would be somebody with 5 or 6 symptoms from only the inattentive cluster of symptoms, not the hyperactive/impulsive group. The reason it’s called predominately inattentive rather than just inattentive is because you can have some of the hyperactive impulsive symptoms but not enough to meet the threshold criteria. The least common presentation is called predominantly hyperactive/impulsive presentation, and that is seen in less than 5% of patients.

There is 1 other category of ADHD, unspecified ADHD. That includes someone who you really think has ADHD. This type of patient meets several of the criteria required, but they don’t quite meet full criteria across all the categories.

Based on my clinical experience, ADHD is not a uniform disorder. It has many clinical presentations. It’s a very heterogeneous disorder clinically, as far as the way it presents—the pattern of symptoms. We already talked about the different presentations, such as combined or predominantly inattentive or predominately hyperactive/impulsive. Also, it’s heterogeneous in regard to the various comorbidities or associated conditions that can be seen. It varies from individual to individual. This is why a skilled clinician really needs to keep an eye out for this and be aware of the various presentations clinically, as well as the various associated conditions and comorbidities.

It’s very important to realize that ADHD, probably neurobiologically, is a heterogeneous disorder, and that may underlie some of the variability in the way it presents clinically.

Talking about the prevalence and the impact of ADHD, the clinical burden, it does differ between children and adults. Various epidemiological studies have been done estimating the prevalence of ADHD in the United States and around the world. In the United States, a 2016 survey showed that approximately 9% of children had been diagnosed with ADHD. A survey called the National Comorbidity Survey Replication looked at the incidence of ADHD in adults and found the rate to be approximately 4.4%.

This is a neurobiological disorder that starts in childhood. We don’t think you actually outgrow this disorder. We think you might outgrow the symptomatic criteria or the diagnosis but not the disorder, and this is because as our brains age and mature, the symptoms can change and mature. For instance, the hyperactive/impulsive symptoms become less prominent and may occur internally—someone is more restless rather than overtly hyperactive. Also, adults learn coping strategies that make the symptoms less prominent and less impairing.

As far as the clinical burden, we know that ADHD has a significant impact on all phases of a person’s life, including school, work, home function, and social relationships. We know that ADHD can be associated with significant underachievement, behavioral problems in childhood, various comorbidities in adulthood, marital and relationship problems, financial difficulties, and even things such as driving—more speeding tickets and accidents. It can be associated with medical conditions in adulthood as well. There is a significant clinical burden across all phases of a patient’s life. This speaks to the urgency or the importance of doing a careful assessment for all the different conditions and instituting an individualized treatment plan.

Transcript Edited for Clarity