Within the past 25 years the United States has suffered an unprecedented epidemic of attention deficit hyperactivity disorder (ADHD) among the nation’s children. From the late 1980s to the early 2000s the rate of diagnosis soared 500 percent. Today 5 to 10 percent of all U.S. children between the ages of 6 and 18 have been diagnosed with ADHD. What is driving this surge?
A recent study by Notre Dame economist William Evans and colleagues at the universities of Minnesota and North Carolina State suggests that, at least in part, the epidemic may be driven by misdiagnosis. The economists reach that conclusion based on statistical analyses of data on ADHD diagnosis, medication treatment and the age of those diagnosed relative to peers enrolled in school.
The researchers discovered that children who are “older for their grade” are less frequently diagnosed and treated for ADHD. Children born just after the cutoff date for enrollment and therefore relatively old for their grade had a significantly lower incidence of ADHD diagnosis and treatment than classmates born just before the cutoff and, therefore, young for their grade. All things being equal, such a disparity should not exist. The fact that it does suggests something other than the disorder is causing the increase in diagnosis.
Evans and his colleagues conclude that some children may be mistakenly diagnosed with ADHD because they exhibit more immature behavior than older classmates. The researchers note that diagnosing ADHD is difficult. Children who have the disorder are hyperactive, have a difficult time staying focused and act impulsively, but even non-ADHD children occasionally exhibit such behavior. For those truly having the disorder, however, the behaviors are pervasive and persist into adulthood.
Typically, teachers bring ADHD-like symptoms to the attention of parents, who then take their child to a pediatrician or family physician for evaluation.
The problem may be that such children are being compared to all other children within their class, when their true peers should be children of a similar age within their class. In the early grades, the social scientists note, the relative age difference within a grade is substantial, up to 20 percent in kindergarten. In some cases, therefore, it may be that age-appropriate immaturity is mistaken for ADHD.
How serious is the problem? According to the economist’s analysis, approximately 1.1 million children may have received an inappropriate diagnosis and more than 800,000 received stimulant medication due only to relative maturity.
Evans and his colleagues note that treating children who don’t really need care for ADHD is economically wasteful and potentially unhealthy. A 2007 review by the Federal Drug Administration found that the stimulant drugs used to treat ADHD, such as Ritalin, may have serious long-term effects which might lead to later cardiovascular or psychiatric problems. Another concern is that long-term exposure to the drugs may have an adverse effect on a child’s developing brain.
John Monczunski is an associate editor of Notre Dame Magazine.