Methodology
Lead researcher Marc Kaufman and his colleagues first established the rate of blood flow to the brain in male and female occasional cocaine users. An intravenous dose of cocaine (0.4 mg/kg) was administered to nine men and 13 women. Men were studied once while women were examined during different phases of their menstrual cycle phases (days 3-8, follicular phase and 18-24, leutial phase) after the beginning of menstruation.

Reduction in blood flow to the brain was measured with Dynamic Susceptibility Contrast functional magnetic resonance imaging (MRI), which uses a magnetic resonance contrast agent to detect changes in blood flow.

Results
In the follicular phase, when estrogen levels are high and progesterone levels are low, cocaine did not alter the amount of blood in the brain. By contrast, a 10 percent reduction in blood was found in women during their luteal menstrual cycle phase, when progesterone levels rise; male subjects incurred a 20 percent loss. These findings suggest that cocaines effects on blood vessels in the brain differ as a function of sex and menstrual cycle phase, and imply that progesterone in women and testosterone in men may enhance cocaine-induced vasoconstriction, while estrogen in women may blunt cocaines vascular effects.

Significance of Findings
Previous studies have asserted that chronic cocaine users are found to be more prone to strokes than non-abusers of the drug. Abusers have also been found to suffer damage to electrical activity of the brain, which may be secondary to reduced blood flow.

Estrogen, or a synthetic estrogen-like compound, could be helpful in treating the two percent of Americans needing relief from cocaine addiction, by reducing damage caused to the brain by the addictive drug. Such benefits could extend beyond drug using populations. For example, treatments that improve brain blood flow might al
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Contact: Donna Krupa
703-967-2751
American Physiological Society
18-Oct-2001