By Justine van der Leun Aug 11th 2010 4:00PM
Women have long argued that menstruation affects their bodies and minds, and a new study may prove they're right.Doctors and scientists understand that chronic pain can cause functional and structural changes in the nervous system. Now a study out of Taiwan shows that cyclical pain experienced during menstruation can have a similar effect. The study, which will be published in the September issue of Pain, reports that menstrual cramps can alter the brain and nervous system. Cramps accompany menstrual flow in about 50 percent of women -- only 5-15 percent of whom experience severe pain. Researchers wanted to see how the nervous system reacted to severe cramps and used MRI scans to investigate.Thirty-two women who experienced severe cramp-related pain enrolled in the study and were matched with a control group of 32 women who did not experience severe pain. The women, whose mean age was 24 and who had all experienced pain for a mean number of 10 years, were given MRI scans during the pain-free, periovulatory portion of the menstrual cycle.Researchers looked at the women's gray matter -- the main component of the central nervous system. They found multiple regional changes in the women with pain. Decreases in gray matter volume were spotted in areas of the brain involved in pain transmission and higher sensory processing. Meanwhile, volume increases were found in areas involved in pain modulation and endocrine function, reported Med Page Today. These changes did not disappear when the menstrual cycle was over.For example, the women had increased volume in the hypothalamus, which helps regulate the menstrual cycle and responds to high estrogen levels. Cramps are possibly caused by heightened production of prostaglandins, which may be accompanied by elevated levels of estrogen. The researchers hypothesized that if the estrogen lambastes the hypothalamus, it may force the hypothalamus to react, resulting in structural changes to the area. "This shows that not only sustained pain but also cyclic occurring menstrual pain can result in longer-lasting central changes," says Dr. Jen-Chuen Hsieh, the study's lead scientist and a professor at the Institute of Brain Science at National Yang-Ming University, in a press release.More studies have to be conducted to find out if these changes in the brain are reversible.