ADOLESCENTS ESPECIALLY SENSITIVE TO ADDICTIVE DRUGS

Researchers have found evidence in animals that the young, adolescent brain
may be more chemically sensitive to addictive drugs like cocaine and
amphetamines than the brains of either adults or newborns.

Philadelphia scientists discovered a significantly greater increase in
amounts of a key gene-regulating protein in the brains of adolescent mice
after long-term exposure to the drugs than they did in either very young
mice or adults.

"An increase in this protein may be important because it could also affect
other molecules that could lead to long-lasting changes in the brain in
response to psychostimulant drugs," said Dr. Michelle Ehrlich, a professor
of neurology at Thomas Jefferson University's medical college.

The findings were reported Friday in the journal Neuroscience.

Such drugs affect cells in the front of the brain that control movement as
well as some thinking skills and the region that produces "reward"
sensations linked to addiction.

"The time just before the onset of puberty and adolescence are when
addiction usually begins, so we will be looking to see if this increase is
a clue to sensitivity to such drugs as therapeutic agents," Ehrlich said.

She said the study raises several questions, including whether behavior
actually changes as a result of the increase in protein activity, and
whether the different responses mean that pre-teens and teens are more
prone to use stimulant drugs or more tolerant of higher doses of the
medications.

"These are relevant both to addiction and to therapeutic use of these
medications (for attention-deficit syndrome) in these age groups," Ehrlich
said, adding the findings may allow doctors to better target new addiction
treatments.

Ehrlich, working with Ellen Unterwald of Temple University and others,
found that in adult mice (about 6 weeks of age), and newborns, the protein,
called Delta FosB, was increased in the front part of the brain associated
with motor activity, particularly hyperactivity and attention-deficit
syndrome. They did not find similar increases in a nearby part of the brain
associated with reward from taking psychostimulants.

But in the brains of the adolescent mice, they found that the protein was
made in increased amounts in both areas of the brain in response to the drugs.

"The implications are that there is an increased adaptation in the
adolescent brain in to these psychostimulants," Ehrlich said.

On the Net: www.tju.edu

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