Rates of ADHD have increased significantly in the U.S. over the past several years, leading to an ongoing debate about the validity of the disorder. Because you are likely to be asked by patients (or their parents) about this issue, it’s helpful for you to have some background in exactly how much the prevalence has increased, and what factors may be driving this trend.
One of the key sources of information on ADHD prevalence in the U.S. is the National Survey of Children’s Health (NSCH). In partnership with the Centers for Disease Control and Prevention (CDC), the NSCH methodology entails telephone surveys of randomly sampled families in all 50 states. The specific questions about ADHD include whether a health care provider ever told the survey respondent (usually the child’s parent or guardian) that the child has ADHD—and if a diagnosis was made, whether the youth is taking medication for ADHD. As you can see, the methodology isn’t perfect, as there’s no guarantee that the diagnosis was accurate, but it does give us a good idea about the prevalence of diagnosed ADHD as perceived by parents.
This survey has been conducted three times in the past decade, yielding progressively increasing prevalence rates: 7.8% in 2003, 9.5% in 2007, and 11% in 2011–12. If the latest 11% prevalence figure is accurate, that would mean that about 6.4 million young people have ADHD in the U.S., or 1 in 9 children (Visser SN et al, J Amer Acad Child Adolesc Psychiatry 2014;53:34–46). Because boys are more likely to receive this diagnosis, their apparent rate is 15%, or nearly 1 in 6—and for boys of high school age, the prevalence is nearly 1 in 5.
Given that there is no objective test for ADHD, it’s reasonable to wonder if the true prevalence of ADHD is rising to this extraordinary extent, or whether it is being overdiagnosed. Keep in mind that the prevalence of ADHD in other developed countries is consistently estimated in the 5%-7% range—casting further doubt on the 11% figure in the U.S. (Polanczyk et al, Am J Psychiatry 2007;164(6):942–948).
In order to explore this issue, my colleague Richard Scheffler (a health economist) and I have done extensive research on the possible causes of the rising rates of the disorder, and we recently published a book summarizing the relevant data (Hinshaw SP and Scheffler RM, The ADHD Explosion: Myths, Medication, Money, and Today’s Push for Performance. New York, NY: Oxford;2014:254).
Despite the tenor of the book’s title, we do not believe that ADHD is a myth. In fact, we believe that the disorder is a legitimate, debilitating condition that responds well to a variety of treatments. Nonetheless, it is also clear that the high prevalence of ADHD in the U.S. may be inflated, and in this article I will summarize some of the factors leading to this potentially artifactual “explosion” of ADHD.
Consumer demand for stimulants for nonclinical purposes
Stimulants clearly improve both the core symptoms of ADHD and the many aspects of cognitive functioning in people with the disorder. However, their ability to improve cognitive function in children and adults without any psychiatric diagnosis is far more questionable (Smith ME and Farah MJ, Psychol Bull 2011;137(5):751–752). Even so, the strong perception exists that stimulants are “smart pills,” whether those benefits can be quantified in study conditions or not. This “likability” of stimulants may lead to inflated diagnoses as people without ADHD may report improved performance, real or imagined. It has also fueled high rates of “diversion”— the taking of medications by the general public, particularly college students.