The ADHD Epidemic: An Outcome of Over-Diagnosis or Robust Psychological Measurement?
In the early 1990s, fewer than 5% of children were thought to have Attention-Deficit/Hyperactivity Disorder (ADHD) (3). Over the past few decades, rates of the disorder have skyrocketed, leading many to refer to its steadily increasing prevalence as an “epidemic”, resulting from large-scale over-diagnosis. Recent data from the Centers for Disease Control and Prevention have indicated that as of 2011, approximately 11% of children 4–17 years of age have been diagnosed with ADHD, with the number of diagnoses continuing to rise (1).
Some studies suggest that of the 6.4 million (1) children diagnosed with ADHD, many are unlikely to have any kind of physiological difference that would make them more distractible than the average child (3). It is likely, they claim, that the rapid increase in diagnosis is not due to biological or environmental changes that make physiological differences more prevalent, but rather has to do with a general lack of diagnostic rigor on the part of physicians and clinicians (3). For example, many reports have been made of children being diagnosed based on a short visit with their pediatrician, suggesting that an ADHD diagnosis is easy to obtain, and often done in pursuit of secondary gains such as access to stimulant medication (2).
The CDC does concede that an objective diagnostic approach to ADHD is still lacking and that different definitions used by researchers have lead to disagreement about the number, characteristics, and outcomes of children with the disorder. However, a recent study by the Centers for Disease Control and Prevention’s National Center for Health Statistics suggests a much more nuanced and comprehensive picture of ADHD diagnosis than proponents of said “epidemic” have described. In this large, nationally representative survey of parents with children ages 2–15 who have ADHD, data were collected on the epidemiology of the diagnosis, presence of other disorders, types of medication and behavioural treatment the child received, and the types of symptoms present at diagnosis.
The results stand in striking contrast to the belief that ADHD diagnosis lacks rigour in that the vast majority of children who receive an ADHD diagnosis in the U.S. are undergoing some form of psychological testing (5). Almost 90% of children were given a scientifically valid behavioural rating scale or checklist, and 68% also underwent extensive neuropsychological testing, the gold diagnostic standard for many childhood conditions. In addition, 96% of parents were part of the conversation about their child’s behaviour, and in 82% of cases, another adult who was not the child’s parent was asked about the child’s behaviour. Furthermore, highly trained professionals — pediatricians — are doing most of the diagnosing (39%) (2).
These findings indicate that most ADHD diagnoses are made based on objective empirical data, and the use of established best-practice guidelines, some of which include behavioural rating scales and checklists (5). So, perhaps the so-called ADHD “epidemic” of recent years would be better understood as the result of improvements in psychological testing, leading to an increase in diagnosis of a previously under-diagnosed disorder.
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(1) Data & Statistics. (2016). Retrieved January 25, 2016, from http://www.cdc.gov/ncbddd/adhd/data.html
(2) Grohol, J. (2015). ADHD Overdiagnosis? Most Done After Checklists, Neuropsychological Testing. Retrieved January 25, 2016, from http://psychcentral.com/blog/archives/2015/11/20/adhd-overdiagnosis-most-done-after-checklists-neuropsychological-testing/.
(3) Koerth-Baker, M. (2013). The Not-So-Hidden Cause Behind the A.D.H.D. Epidemic. Retrieved January 25, 2016, from http://www.nytimes.com/2013/10/20/magazine/the-not-so-hidden-cause-behind-the-adhd-epidemic.html?_r=0.
(4) Research. (2016). Retrieved January 25, 2016, from http://www.cdc.gov/ncbddd/adhd/research.html.
(5) Visser, S. N., Visser, S. N., Zablotsky, B., Holbrook, J. R., Danielson, M. L., & Bitsko, R. H. (2015). Diagnostic Experiences of Children With Attention-Deficit/Hyperactivity Disorder. National health statistics reports, (81), 1.
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