Subject: ARTICLE: New Study Shows Early Ritalin May Cause long-term effects
on Brain


New study shows early Ritalin may cause long-term effects on the brain
Research of animal models released at ACNP Conference

San Juan, Puerto Rico, December 12, 2004 – A new study conducted in rats by
the National Institutes of Health (NIH) and McLean Hospital/Harvard Medical
School suggests that the misdiagnosis of attention-deficit hyperactivity
disorder (ADHD) combined with prescription drug use in children may lead to
a higher risk of developing depressive symptoms in adulthood.
This work, released at the annual American College of
Neuropsychopharmacology (ACNP) conference in Puerto Rico, is among the first
to examine the effects of early Ritalin exposure in rats on behavior and
brain function during the later periods of life.
"Attention-deficit hyperactivity disorder can be a serious medical problem
for children and their parents," says lead researcher William Carlezon,
Ph.D., director of McLean Hospital's Behavioral Genetics Laboratory and
associate professor of psychiatry at Harvard Medical School. "While Ritalin
is an effective medication that improves the quality of life for many
children with ADHD, accurately diagnosing and identifying the correct
treatment regimen for the disorder is essential, especially when considering
health effects that can last through adulthood."
Ritalin is a generic medication prescribed for children with
attention-deficit hyperactivity disorder (ADHD), a condition that consists
of a persistent pattern of abnormally high level of activity, impulsivity,
and/or inattention. Usually diagnosed in children of preschool or elementary
school age, ADHD has been estimated to affect 3 to 12 percent of children
and is twice as common among boys. Children with ADHD are also likely to
have other disorders, such as a learning disability, oppositional defiant
disorder, conduct disorder, depression, or anxiety.
Because most children show some of these behaviors of inattention and
hyperactivity at times, the diagnosis of ADHD is a complex process that
should involve specialists. It is critical to determine whether a child's
behavior is simply immature or exuberant, related to another issue such as a
vision problem or learning disability, or is characteristic of a disorder
such as ADHD.
In the work funded by the NIH, Dr. Carlezon and his chief collaborator, Dr.
Susan Andersen, examined the effects of exposing rats to Ritalin during
early development on behaviors later in life. They exposed normal rats to
twice-daily doses of Ritalin during a period that is equivalent to
approximately 4-12 years of age in humans. Examining the behavior during
adulthood, Carlezon and Andersen conducted several types of tests that all
showed that the animals had a reduced ability to experience pleasure and
reward, particularly when it was measured by sensitivity to cocaine. In
addition, they found that the animals exposed to Ritalin during
pre-adolescence were more prone to express despair-like behaviors in
stressful situations (such as swim tests) as adults. Overall, the animals
showed more evidence of dysfunctional brain reward systems and
depressive-like behaviors in adulthood.
These findings are critical because they suggest that Ritalin can have
long-term consequences on normal-functioning brains. The study is
particularly relevant when considering the difficulty in correctly
diagnosing children with ADHD. In 1999, approximately 90 percent of children
diagnosed with the disorder were taking Ritalin, with children beginning
drug therapy at younger ages today, even during preschool in some instances.
There is increasing evidence to suggest that correct diagnosis of ADHD is of
the highest importance – children who are misidentified as having ADHD and
subsequently placed on prescription drug therapy could face possible
impaired brain performance as adults.
"Ritalin can be highly effective in the treatment of ADHD, but our work
highlights the importance of getting a proper diagnosis", states Carlezon.
"Although individuals such as teachers and coaches can assist in identifying
children with the disorder, an experienced health care professional is
best-trained to make the final assessment and recommend avenues of
treatment."
ACNP, founded in 1961, is a professional organization of more than 700
leading scientists, including four Nobel Laureates. The mission of ACNP is
to further research and education in neuropsychopharmacology and related
fields in the following ways: promoting the interaction of a broad range of
scientific disciplines of brain and behavior in order to advance the
understanding of prevention and treatment of disease of the nervous system
including psychiatric, neurological, behavioral and addictive disorders;
encouraging scientists to enter research careers in fields related to these
disorders and their treatment; and ensuring the dissemination of relevant
scientific advances.

http://www.eurekalert.org/pub_releases/2004-12/g-nss121004.php


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