Studies Linking Ritalin
Highlight Risk of Overdiagnosing ADHD
By TARA PARKER-POPE - Wall Street Journal
January 25, 2005; Page D1
|New research is raising questions about the long-term
effects of Ritalin and other drugs widely used to treat
attention-deficit hyperactivity disorder.
While most people agree that Ritalin and similar drugs can
dramatically improve the lives of kids suffering from ADHD,
doctors and parents have long been concerned about how the drugs
might affect a child's developing brain.
Now, new studies in rats suggest that methylphenidate, the
generic name for Ritalin , may permanently alter the brain and
may lead to depression in adulthood.
While the studies have limits -- a rat's brain is obviously very
different than a child's -- the research nonetheless highlights
the need to be sure of an ADHD diagnosis before putting a child
on medication. ADHD has been estimated to affect 3% to 12% of
children and is twice as common among boys as in girls.
But the criteria for the disorder -- such as whether a child is
easily distracted, doesn't seem to listen or can't sit still --
are highly subjective and could easily describe many healthy
children. Some psychiatrists believe that as many as 15% of kids
diagnosed with ADHD actually suffer from some other problem that
wouldn't be helped by drugs -- such as a learning disability, a
sleep disorder or even a difficult relationship with a teacher.
Efforts are increasing to make ADHD diagnoses less subjective.
Now, "many kids are put on Ritalin when there's very weak
evidence," says Eric Nestler, chairman of the psychiatry
department at the University of Texas-Southwestern Medical
Center in Dallas.
This latest research has particular significance for healthy
children who have been wrongly diagnosed and put on ADHD
medication. In December at the annual meeting of the American
College of Neuropsychopharmacology, researchers from Harvard
Medical School's McLean Hospital in Belmont, Mass., presented a
study on depressive symptoms that developed in adult rats
exposed to Ritalin early in life. Researchers at the University
of Texas-Southwestern in Dallas have reported similar findings.
While a rat study certainly can't be the final word on the risks
or benefits of any drug, the animals are a particularly valuable
proxy to monitor drug effects in a young brain, because for
ethical reasons it's difficult to study children.
In both rat studies, young rats were exposed daily to Ritalin or
a placebo, using doses that mimicked Ritalin use in childhood.
The treatment was stopped for a period of time, and adult rats
were tested for signs of depression and despair. The researchers
found that rats exposed to Ritalin were less interested in sugar
water and sexual activity than their counterparts who had never
been given the drugs.
And in stressful situations, Ritalin rats gave up on tasks more
quickly. In a Harvard test, the rats were left to swim in a tank.
The Ritalin rats gave up and floated after about three minutes,
nearly two minutes sooner than other rats.
Notably, the rats were also exposed to cocaine. The Ritalin rats
were far less interested in the drug than other rats. That
suggests kids exposed to Ritalin probably aren't at higher risk
for abusing drugs. But it may also indicate that brain pathways
involved in pleasure and aversion, which can subsequently
influence behavior, have been changed, increasing the risk for
The research measures only the impact of Ritalin on a healthy
rat brain. As a result, the studies are best extrapolated to
healthy kids, and emphasize the importance of getting the right
diagnosis before putting a child on Ritalin . While only Ritalin
was studied, scientists say it's reasonable that other
stimulants used to treat ADHD, such as Concerta or Adderall,
would likely show similar effects.
ADHD OR NOT?
Some symptoms that may result in a diagnosis of attention-deficit
or hyperactivity problems if seen often enough.
• Does not give close attention to details or makes careless
mistakes in work
• Does not seem to listen when spoken to directly
• Does not follow instructions and fails to finish work
• Loses things needed for tasks and activities (toys, books,
• Easily distracted
• Fidgets with hands or feet or squirms in seat
• Talks excessively
Source: American Psychiatric Association: Diagnostic and
Statistical Manual of Mental Disorders
"In defense of parents, they figure giving Ritalin is like
giving aspirin," says William Carlezon, a Harvard associate
professor of psychiatry and co-author of the most recent study.
But "one of the important implications of our work is that the
effect of Ritalin doesn't go away."
ADHD can be difficult to diagnose, and doctors rely on reports
from teachers and parents to determine how disruptive the
problems really are. But such methods are notoriously unreliable.
In one recent McLean study, data collected from 1,000 children
showed some teachers never rated any kids with ADHD while others
singled out nearly all the boys as potentially ADHD. "Teachers
differ significantly in their sensitivity and tolerance for
certain behaviors," says Martin Teicher, director of the
Developmental Biopsychiatry Research Program at McLean.
Dr. Teicher has developed the McLean Motion and Attention Test,
or M-Mat, which uses a computer to confirm an ADHD diagnosis.
During the 15-minute test, the child completes a task on the
computer while wearing a headband with an infrared light. The
light allows a video camera to track his or her movements and
fidgeting. A normal child will fidget about 1,000 times, while a
child with ADHD has been shown to move three to four times more.
In children whom a doctor had previously diagnosed as having
ADHD, the computer agrees about 85% of the time. Dr. Teicher
notes that the test isn't a substitute for the opinions of
teachers, parents and doctors in diagnosing behavioral problems,
but that it can be useful for helping to ferret out the
estimated 15% of cases in which a learning disability or other
problem has been mistaken for ADHD. It can also help confirm
whether a drug like Ritalin is working.
McLean researchers are working with a private firm to expand use
of the test, which is now used in about 60 hospitals around the
country. For a list of hospitals who offer the M-Mat, go to