Immaturity Officially a Disease: You Saw It Here First

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.  

Now, a year and a half later, another study, published in a more widely read journal and reported widely in the news, came up with the exact same conclusion.  (“Influence of relative age on diagnosis and treatment of attention-deficit/hyperactivity disorder in children” by Richard L. Morrow, et. al., Canadian Medical Association Journal, published on line March 5, 2012). 

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.

This number was even more dramatic in the girls, with those born in December 70% more likely to be diagnosed with ADHD than girls born in January.

In addition, both boys and girls were at a significantly higher risk of being prescribed an ADHD treatment medication if they were born in the later month than in the earlier one.

 "It could be that a lack of maturity in the youngest kids in the class is being misinterpreted as symptoms of a behavioral disorder," said lead author Richard L. Morrow.  


Could be?  About about “is?”

Some of these behaviors could include not being able to sit still, not being able to focus and listen to the teacher, or not following through on a task, he added.


"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.

The study authors went on to  note that potential harms of overtreatment in children include increased risk for cardiovascular events, as well as effects on growth, sleep, and appetite.  There was no mention of the harm of making this diagnosis and using these potentially toxic medication instead of investigating and addressing possible psychosocial reasons for “hyperactivity” such as a chaotic family environment or abusive and/or inconsistent parenting practices.

This brings up the issue of the risk to the heart and the rest of the cardiovascular system posed by stimulant use.  There have been several studies recently published that have been reported in both the medical and lay media that claim that this risk is minimal.  


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).

That study about sleeping pills seemed to me to be a bit hard to believe, especially since epidemiological studies are notoriously unreliable.  But even if the numbers are valid, the fact that the risk of death from all causes increases most likely means that there is  some other characteristic, or a bunch more characteristics, of the population of people who are prescribed sleepers that are not characteristic of other populations. Those additional factors might explain the findings.

As for stimulants, in the February, 2012 issue of the American Journal of Psychiatry, there is an article on methylphenidate (Ritalin and its variations) and risk of heart problems in adults. Using a large medication database, researchers matched about 44000 methylphenidate (MPH) users and about 176,000 controls. 


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.

The news stories about the study on the benzo’s seemed to be meant to scare people out of using them, while the stories about increased risk in stimulant users seemed to be meant to reassure people about using them.  Of course, both of these studies described relative risk and not absolute risk (See my post Stats.com from November 2, 2011).   


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.

Physicians will not be able to see the increased risk in their clinical experience.  As Nassir Ghaemi says, “They don't happen in 10-20% of patients in our practice; they happen in 1-2% (or 0.1-0.2%), and so, the average clinician, faced with a welter of patients, doesn't make the causal connection.”

The question should be, what are the risks versus the benefits from taking the medication.  For sleeping pills, for instance, one might want to know if there is a much larger increased risk of death for people who are sleep deprived.  For example, before the practice was stopped, medical interns would routinely work 36 hour shifts.  Fatal accidents on the car trip from the hospital back home were not all that unusual.

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.

An editorial in the same issue of the American Journal of Psychiatry as the study of Ritalin in adults sounded reassuring about stimulant use.  Based on that study, I’m not so reassured.