by Neil Caudle

Several years ago, as research into addiction gathered steam, Mitch Picker noticed a troubling omission: What we were learning came mostly from males. "Everyone avoided females," Picker says, "partly because of the risk of endangering pregnancies but also because the menstrual cycle causes so much fluctuation in hormone levels."

Those fluctuations, researchers had assumed, would confound the data and complicate research. But to Picker, professor of psychology, it seemed unwise to assume that what we'd been learning about addiction or pain relief in males would apply to females. For the last four years, Picker has investigated how sex differences determined largely by genetic factors influence responses to drugs. In many cases, the differences are dramatic. A number of researchers have found that females tend to be more sensitive than males to morphine and other opiates. Some pain relievers and anesthetics work for women but offer little or no help for men. Eventually, Picker says, the most effective anesthetics and analgesics may be highly individual, tailored to the sex, age, and genetic background of the patient.

But when it comes to addiction, findings from studies by Picker and his colleagues strike an ominous note. "We have data from animal studies as well as human studies indicating that some drugs have a greater abuse potential in females," he says. "In the past, there were far more male drug users than there were females. But if the culture changes, and more females begin experimenting with drugs, their drug use may be more likely to lead to addiction. This is a serious problem, and it's just now coming to light."

Neil Caudle is editor of Endeavors magazine.