 |
| 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.
