Women More Sensitive to Cocaine

Presented with a choice between cocaine and food, female rats choose the drug while male rats go for the grub, a new study finds. The result may help clarify differences in addiction between men and women, scientists reported on November 14 at the annual Society for Neuroscience meeting in San Diego.

Kerry Kerstetter of the University of California, Santa Barbara, and colleagues trained rats to press one lever for food and another for cocaine, then presented both levers at the same time. The females consistently chose the cocaine lever; the males mostly chose food. The researchers' working explanation is hormonal: estrogen appears to amplify cocaine's rewarding effects, making females more vulnerable.

The finding echoes a broader pattern in human addiction research. Women tend to start using stimulants later than men but escalate to dependence faster — a phenomenon clinicians have called "telescoping." The animal data suggests the biology may be tilted from the start: the same dose of cocaine, delivered to the same brain circuitry, hits harder in females.

There are caveats worth stating. Rats pressing levers are not women deciding about drugs, and estrogen in a rodent does not map neatly onto human hormone cycles. But the sex differences in addiction are too consistent across species and studies to ignore, and they point toward a treatment approach the field has been slow to adopt: addiction medicine that accounts for sex.

The UCSB team's follow-up work — published in Neuropsychopharmacology — confirmed the estrogen link, showing that the sex difference in food-versus-cocaine choice is mediated by estrogen itself.

The full paper, "Sex Differences in Selecting Between Food and Cocaine Reinforcement are Mediated by Estrogen," is freely available on PubMed Central.