|The kid in red is in the same grade and classroom as the other four|
In my post of September 20, 2010, Immaturity in YoungChildren: Officially a Disease, I described two studies published in a very obscure journal, the Journal of Health Economics, that both found nearly identical data about the diagnosis of ADHD in school children. In the these articles, two different research groups (Evans, Morrill, &Parente, 29, 2010 657–673; Elder, 29 2010, 641–656) using four different data sets in different states came to the same conclusion.
In one, roughly 8.4 percent of children born in the month prior to their state’s cutoff date for kindergarten eligibility – who typically become the youngest and most developmentally immature children within a grade – were diagnosed with ADHD, compared to 5.1 percent of children born in the month immediately afterward. The study also found that the youngest children in fifth and eighth grades were nearly twice as likely as their older classmates to regularly use stimulants prescribed to treat ADHD! The results of the second study were quite similar.
Translated into numbers nationwide, as Steindór summarized in his comment on my blog, this would mean that between 900 thousand (Elder) and 1.1 million (Evans et al. 2010) of those children under age 18 in the US diagnosed with ADHD (at least 4.5 million) are misdiagnosed.
In a cohort study (a study of a group of individuals with something in common followed over time) of more than 900,000 Canadian children, researchers found that boys born in the month of December (the cutoff birth date for entry to school in British Columbia) were 30% more likely to be diagnosed with ADHD than boys in their grade who were born the previous January.
Could be? About about “is?”
"You wouldn't expect a 6- and 9-year-old to behave the same way, but we're often putting a 6- and 7-year-old in the same class. And we're learning that you can't expect the same behaviors from them," he added. "We would like to avoid medicalizing a normal range of childhood behaviors." No sh*t!
This problem has been complicated recently by the fad of "redshirting" children for kindergarten: overachieving parents purposely starting them at age six rather than five in order to give them a competitive advantage academically over their classmates. Now children in the same class may be as much as two years apart in age.
This is in an interesting contrast to the publicity about an article, published this week in BMJ Open (the online version of the British Medical Journal) that purported to show that the use of sleeping pills increases the risk of dying from all causes by a factor of 4 over just two and a half years. Sleeping pills are generally regarded as far less dangerous and less likely to be abused than stimulants. The FDA categorizes benzos as "Schedule IV" (lower likelihood of abuse) and stimulants as "Schedule II" (most likely to be abused short of the illegal "Schedule I" drugs).
They looked at main the incidence of a cardiac event defined as a myocardial infarction, stroke, ventricular arrhythmia, or sudden death. They found a 117% increased risk - or over double the risk – in the Ritalin group. After adjustment for some potential confounding factors, the risk was still 84% higher.
This means that “double the risk” means the risk might go from, say, a tenth of a percent to two tenths of percent. Double a very small risk is still a very small risk. The absolute risk in this example would have gone up just one tenth of one percent. Still, if millions of people are getting the prescriptions, this increased risk can still turn out to apply to a sizeable number of people.
Then there is the whole question of other, non-pharmacological treatments, which is relevant for both the use of sedatives and stimulants. Of course, they do not work for everyone either.