Researchers at the University of North Carolina at Chapel Hill have found an unexpected signpost pointing to a physical cause for premenstrual syndrome.
Psychiatric researchers compared the reactions to stress of 15 women with documented premenstrual syndrome with those of 15 who did not have PMS.
What they found surprised them and may underscore unusual recent findings by research teams in other medical centers indicating that PMS may not originate in the reproductive organs but in the brain.
“We haven’t pinpointed a physiological basis for PMS, but we have found some physical differences between women who have PMS and those who don’t,” said Dr. Susan Girdler, a research assistant professor in UNC-Chapel Hill’s psychiatry department. The study was paid for through a grant from the National Institutes of Mental Health.
At the lab, people are put in stressful situations to study their reactions.
“We thought they (women with PMS symptoms) would show increased cardiovascular responses, but they didn’t,” Girdler said.
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“In fact, they showed much smaller physiological stress responses than did the women without PMS. Regardless of when we caught them in their (monthly) cycle, their stress responses were much smaller; their blood pressure and heart rate did not go up as much as women without PMS.”
There were more surprises. The researchers expected to find that women with PMS would have higher neuropsychological responses during the time they experienced PMS or during their menstrual periods. Instead, researchers found that while women without PMS did have different neurochemical responses to cognitive tests during the menstrual cycle, women with PMS did not.
In short, Girdler said, women with PMS appear to be stressed constantly, whether they are experiencing PMS symptoms or not.
“It’s very strange; it wasn’t what we expected,” she said. “Something in their brain is not regulated correctly, and it’s putting out adrenaline responses all the time. The real cause of this disorder may be centered in a chronic disregulation in the brain.”
The findings have prompted the university to ask for further federal grants to continue its studies.
“There’s so little good research done on women and PMS,” Girdler said. “We are just beginning to understand that we need to delve into this.”