Ritalin Side Effects Rare in Long Run?
ADHD Drug Ritalin Shows Few Lasting Brain Side Effects in Tests on Rats
WebMD News Archive
July 3, 2007 -- Ritalin, a drug used to treat attention deficit
hyperactivity disorder (ADHD), may not leave long-term side effects on the
brain, a new study shows.
The Ritalin side effects study, published in The Journal of
Neuroscience, was conducted on rats, not people.
The researchers included Teresa Milner, PhD, of the neurobiology division at
New York's Weill Cornell Medical College.
ADHD is typically diagnosed in children, and Ritalin is one of the most
commonly prescribed ADHD drugs, Milner's team notes.
The researchers injected young male rats with Ritalin for about a month,
starting when they were 1 week old, to mimic Ritalin use in people, who take
Ritalin by mouth.
The scientists split the rats into two groups. They examined the brains of
one group of rats immediately after Ritalin treatment ended.
For comparison, the researchers checked the brains of the second group of
rats three months after Ritalin treatment ended. By then, those rats were
The rats also took two behavioral tests. In one test, the rats were placed
in an open field and the researchers watched to see how quickly they scampered
to find cover. In the other test, the rats had to navigate through a maze.
Ritalin Study's Results
The scientists noticed some subtle, short-term structural changes in the
rats' brains immediately after Ritalin treatment ended. But those differences
weren't major, and they faded within three months.
The Ritalin-related brain changes appear to "largely resolve with
time," at least in rats, write the researchers.
As for the behavioral tests, the results were mixed.
In the maze test, the adult rats that had stopped Ritalin treatment three
months earlier appeared to be less anxious than rats typically are. But that
wasn't true in the other behavioral test, so the researchers didn't draw any
firm conclusions about Ritalin's long-term side effects on normal anxiety.
The study focuses on the brain and behavioral side effects of Ritalin, not
all possible side effects of the ADHD drug. It's not clear if the findings
apply to people.