March 3, 2000 (Atlanta) -- Women with a severe form of premenstrual syndrome are more sensitive to pain and are more likely to have chronically lower levels of beta-endorphins, the body's natural painkilling hormones, according to a new study. Called premenstrual dysphoric disorder (PMDD), it affects millions of women in their reproductive years.

For women with PMDD, emotional symptoms like severe depression, irritability, and anxiety profoundly interfere with their lives during the second half of the menstrual cycle. "These women also suffer from many severe physical symptoms -- migraine, headache, backache, bloating, cramping," lead author Susan S. Girdler, PhD, tells WebMD. Girdler is assistant professor of psychiatry at the School of Medicine at the University of North Carolina at Chapel Hill.

"It's a very severe disorder, yet it's not taken seriously by doctors," Girdler says. "The vast majority of PMDD women coming into my clinic to some extent want to be validated. When I first began this research, I was shocked. Some women have full-blown panic attacks, are afraid to leave their houses, have suicidal thoughts. It continues to be a very misunderstood disorder, yet it's a very important issue for women."

Results of Girdler's small study, which focused just on pain sensitivity, were presented at the American Psychosomatic Society annual meeting this week. While a preliminary study had suggested that women with PMDD have increased pain sensitivity three to seven days before menstruation, Girdler's study showed that the sensitivity extended into all phases of the PMDD woman's cycle.

Hers is the first study to measure blood levels of beta-endorphins while testing pain sensitivity. It supports a growing body of research suggesting that PMDD is a chronic disorder that causes abnormal levels of many hormones, including beta-endorphins, at all times of the month. "It suggests that something happens premenstrually, that elevated sex hormones during that week contribute to symptom expression," says Girdler.

Girdler's study used a tourniquet/blood pressure cuff, which has been proven effective in gauging pain sensitivity, she says. The women were tested during two phases: the premenstrual phase, and the week after menstruation began.