Attention Deficit Hyperactivity Disorder (ADHD) is the most commonly diagnosed behavioral disorder among children. Prescriptions of psychostimulants (such as Ritalin) in children diagnosed with ADHD rose by more than 700 percent between 1991 and 2005. According to a 2006 estimate by the Centers for Disease Control, 4.5 million children under the age of 18 were diagnosed with ADHD; 2.5 million of them regularly use prescription medication to treat ADHD. The dramatic increase in prescription use of stimulants in children is a matter of significant medical and social concern, particularly given the subjective nature of the diagnosis.
Two studies recently published in the Journal of Health Economics reach the same disturbing conclusion: many children are inappropriately disagnosed with ADHD simply because they are immature relative to their classroom peers (Elder doi: 10.1016/j.healeco.2010.06.003 and Evans et al doi:10.1016/j.jheal.eco.2010.07.005). These children are not immature in comparison to their age peers, but in comparison to students who are, in some cases, a full year older. One of the critically important findings of the studies is that children who turn five before the cutoff date for start of kindergarten (typically September 1 in many US school districts) are significantly more likely to be diagnosed with ADHD than children who miss the cutoff. The kids who miss the cut off date will be a year older when they start kindergarten, and a year makes a huge difference in level of maturity and behavior in children. Since the actual difference in age between the two groups is only a matter of days or weeks, there should be no difference in the incidence of ADHD diagnosis. But there is.
The Elder study found that ADHD diagnoses among children born just before their state’s kindergarten eligibility cutoff are more than 60 percent more prevalent than among those born immediately afterward. 10 percent of children born in August are diagnosed with ADHD, compared to 4.5 percent of children born in September. Children born in August are also more than twice as likely to be prescribed stimulants (especially Ritalin), than those born in September. The effect persists throughout the school years. The youngest children in the fifth and eighth grades are twice as likely as their older classmates to regularly use prescribed stimulants to treat ADHD. If these patterns are driven by inappropriate diagnoses, Elder estimates that roughly 20 percent of the 2.5 million children who are treated with stimulants have been misdiagnosed. The driving factor, the author concludes, appears to be teachers using within-grade comparisons of hyperactivity and inattentiveness, rather than more salient within-age comparisons. As a result, subjectively perceived ADHD “symptoms” in young students “may just reflect emotional or intellectual immaturity among the youngest children in the classroom” (Elder, 642).
These findings are profound and disturbing, and have serious and broad implications. The financial costs associated with misdiagnosis and treatment are substantial, affecting families, insurance providers, and taxpayers. Long-term stimulant use may have harmful health effects, including chronically elevated pulse and blood pressure, and attenuated growth in children. No research has been done on the long-term health outcomes of stimulant use in children, and no research (for obvious ethical reasons) has been done on long-term stimulant use in children with no underlying biological or neurological problem. Elder notes, as well, that if younger children are overdiagnosed with ADHD, it is also possible that older children might be underdiagnosed if their behavior is assessed against their younger peers. This could have adverse effects on their academic performance and social adjustment.
It would be interesting to see a socio-economic comparison of children diagnosed with ADHD, because it is likely that socio-economic factors would tend to amplify the problem of age-based misdiagnosis. One of the reasons parents place younger children in school as soon as they are eligible is that keeping them out for an additional year (a practice known as “redshirting” [http://www.nytimes.com/2010/08/22/fashion/22Cultural.html]) imposes substantial economic costs, such as lost work and career years, and daycare expenses. The upshot is that we may be treating a social and economic “disorder” with Ritalin. Greater social support for families of young children, including high quality, subsidized or low-cost daycare, might be a more effective “treatment” than psychostimulants — and with far more salutary side effects — for the diagnosis of immaturity in kindergartners.
Thank you for this extremely valuable article. I continually present to professionals and parents about the the need to better understand the brain in relation to behavior. It is so critical that all of the adults influencing children's lives realize all that contributes to behavior. I will share your contributions to creating this awareness.
Posted by: Deborah McNelis | 10/21/2010 at 12:25 PM