COCAINE CONSTRICTS BRAIN ARTERIES

NEW YORK (Reuters) -- Cocaine use -- even a single dose -- triggers a
constriction of blood vessels in the brain, leading to a risk of stroke and
brain damage, according to a study appearing in the current issue of The
Journal of the American Medical Association.

High-tech brain imaging of cocaine users also suggests that the effect of
cocaine on brain blood vessels is directly related to the dose of the drug
used, and that in frequent or long-term users damage to brain arteries may
be progressive, further increasing risk.

Researchers at Harvard Medical School in Boston, Massachusetts administered
either a placebo or low doses of cocaine intravenously to healthy,
neurologically normal men averaging 29 years of age. All of the men
reported at least some prior exposure to the drug.

The researchers say magnetic resonance angiography imaging of the brain,
performed about 20 minutes after cocaine ingestion, detected constrictions
of cerebral blood vessels in 8 of 17 of those subjects who received low
doses of cocaine, compared with just 1 of 7 of those who received a placebo.

The team noted that those who received a larger dose of cocaine had more
evidence of cerebral vasoconstriction than those who received smaller doses
of the drug, indicating a dose-effect relationship.

They also found more of an effect among more frequent users, indicating
"that prior cocaine use may have cumulative effect in promoting (the)
angiographic changes indicative of vasoconstriction (narrowed blood vessels)."

Experts have long associated cocaine use with an increased likelihood for
stroke, and the Harvard team speculate that the pressures placed on
arteries by long-term, high-dose cocaine ingestion may play a key role in
triggering drug-related attacks.

Constriction of the blood vessels leading to the brain can also impair
intellectual function. The study authors say their findings help explain
"the cognitive dysfunction observed in long-term cocaine abusers."

"Together, these findings highlight the potential dangers of cocaine use on
cerebrovascular function and document the importance of developing
effective prevention strategies as well as treatments that protect against
cocaine-induced vascular dysfunction," conclude the study authors.

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