When it comes to women and cocaine use, it appears estrogen makes the female brain more susceptible to addiction. A study says the drug exhibits its strongest effect on a woman’s brain during her menstrual cycle. It’s this hormone fluctuation that makes women much more sensitive to the drug than men.
The study, published in the journal Nature Communications, explains that estrogen intensifies and feeds the dopamine reward pathway.
It also states that, if used, cocaine is most potent during a woman’s period when her estrogen levels are the highest. This finding could introduce the idea of birth control pills being a part of future addiction intervention treatments.
“Our study will change the way we think about addiction research to emphasize the need to further understand female subjects, as most research on addiction has been conducted in male subjects,” says Erin Calipari, PhD, co-first author on the paper and a postdoctoral fellow at the Icahn School of Medicine. “Further study of the estrogen-reward pathway is important, as it is quite possible that estrogen may have similar effects on other forms of substance abuse.”
Why More Women Get Addicted to Cocaine Than Men
Researchers wanted to uncover why women were more apt to be addicted to cocaine after trying it than men. Overall addiction rates are higher in men, but research shows that, when exposed to cocaine and other drugs, females were more prone to choose cocaine and more likely to become addicted to it than men.
Women were also the gender most likely to try cocaine at an earlier age, take larger amounts of the drug, and have the most difficulty abstaining from the narcotic. In addition, female cocaine users reported experiencing a more intense high from the drug when their estrogen levels were raised during menstruation or estrous cycle.
Animal Trials Offer an Explanation
Mice were used in the trial because they exhibit the same sex differences in drug use as humans. Female mice at various points in their cycles were tested as well as male mice, and tiny fiber optic probes were fixed to the areas of the rodent’s brain that involve the dopamine reward pathway.
Research showed that estrogen affected the quantity of dopamine released by neurons when cocaine was used. The hormone also affected how long dopamine stayed in the synapse between brain cells. Both of these actions were amplified by the pleasurable effects of cocaine and boosted by the increased estrogen levels in female mice. When male and female mice were linked to the pleasure/reward areas of their cages, they spent more time on the side that was paired with cocaine. And because of the enhanced reward they received from their cocaine use, the female mice stayed on the cocaine side of the cage at a much greater rate than the male mice.
“The mice quickly learned that a particular environment is linked to drugs, and we demonstrated that when these mice, especially females at the height of their estrous cycle, were put into that environment, it stimulated a dopamine reward signal even without cocaine use,” Dr. Calipari says. “It is the same kind of strong, learned response that we know happens in humans.”