ADHD update: New data on the risks of medication
Medications — chiefly the stimulants dextroamphetamine and methylphenidate — are
the only proven treatment for attention deficit hyperactivity disorder
(ADHD), with its symptoms of distractibility, impulsiveness, and hyperactivity.
But the benefits of stimulants last only as long as patients continue
to take them, and worries about the risks of long-term use are again
in the news.
Blood pressure and heart problems. Stimulants raise blood pressure
and heart rate. New data are fueling a debate about how dangerous this
is for people who take the drugs for extended periods. In spring 2006
an FDA panel reported on a study of physicians’ reports on ADHD
medications recorded in its Adverse Events Reporting System database.
More than 300 people taking the medications died suddenly. Only 25 of
these deaths appeared to be drug-related, and autopsies indicated pre-existing
heart abnormalities in some of these cases. There were also 26 incidents
of symptoms such as chest pain, heart attacks, strokes, and arrhythmias.
In a close vote, the panel members recommended a black box warning of
cardiovascular risk on prescription labels.
On the one hand, it’s estimated that fewer than 10% of adverse
drug effects are actually reported. On the other hand, the rate of sudden
cardiac death in the survey was much lower than in the general population.
After further analysis, a second FDA panel canceled the black box warning
but agreed to strengthen present warnings about prescribing these medications
to anyone with high blood pressure or heart defects.
Meanwhile, the British equivalent of the FDA noted seizures and heart
rate irregularities in a few people taking atomoxetine (Strattera), a
new ADHD drug that is not a stimulant. The overwhelming majority of them
had a prior history of seizures (which the drug did seem to exacerbate).
The British agency required updating of the drug’s label.
The bottom line is that ADHD drugs are not likely to cause cardiovascular
problems in anyone who does not already have underlying cardiac risk.
But more such people are now using the drugs, because of the explosive
growth in adult prescriptions. Careful screening and monitoring make
Growth suppression. Many children start taking ADHD medications
young and stay on the drugs for years, so the effect on growth is a persisting
concern. Studies to date offer conflicting evidence.
In a large study with a broad focus, children ages 7–9 were followed
for two years. At the end, those who had continuously taken ADHD medication
during that time were on average half an inch shorter and 8 pounds lighter
than those not taking the medication. To clarify the practical significance
of this effect, researchers will have to do studies taking into account
the adolescent growth spurt.
Abuse and diversion. Investigators examined the records of
64 hospital emergency departments and found 188 visits involving ADHD
medications from August 2003 to December 2005. The overwhelming majority
of the patients were children, and in 60% of cases the cause was intentional
ingestion or an overdose, usually of a medication prescribed for someone
else. About 15% of the patients had cardiovascular symptoms such as chest
pain and high blood pressure; other symptoms included stomach pain, muscle
weakness, and rashes.
The stimulants used to treat ADHD have some potential for abuse, because
crushing pills and snorting (snuffing) them can produce a cocaine-like
high. The overwhelming majority of abusers were taking immediate-release
preparations. These are increasingly being supplanted by extended-release
formulas (and a skin patch), which are absorbed so gradually that they
don’t cause a euphoric sensation and are therefore much less susceptible
So, over all, new findings do not seriously challenge the consensus
that most people who are properly diagnosed with ADHD will decide that
the benefits of stimulant medications outweigh the risks.
December 2006 Update
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