Mayo Clinic Researchers Find Estrogen May Provide Protection From Parkinson's Disease

Mayo Clinic researchers have found that women who underwent hysterectomy had a threefold increased risk of developing Parkinson's disease and that women who received estrogen after menopause had a 50 percent reduced risk of developing Parkinson's disease.

The study is being published in the September 2001 edition of Movement Disorders.

"Our findings imply that early loss of estrogen may increase a patient's risk of developing Parkinson's disease," says Demetrius Maraganore, M.D., a Mayo Clinic neurologist and one of the study's authors. "Our belief is that estrogen may play a role in preventing Parkinson's disease."

The study involved the review of medical records of 72 female patients who developed Parkinson's disease between 1976 and 1995 while they were residents of Olmsted County, Minn. The research focused on the association of Parkinson's disease with type of menopause (natural or surgical), age at menopause and postmenopausal estrogen replacement therapy.

"I think women need to consider our findings in the balance of all of the pros and cons of estrogen replacement therapy," says Dr. Maraganore. "This is something they should discuss with their women's health specialist, whether that be a family physician or gynecologist."

Parkinson's disease is a progressive condition that causes impaired movement and tremor. It may develop when certain movement control circuits deep in the brain become disordered as a result of cell degeneration. Roughly one million Americans suffer from Parkinson's disease.

This is the first study of its kind to find an association between hysterectomy and Parkinson's disease.

"We should not change public health policy on the basis of this study," says Dr. Maraganore. "What our study calls for is more detailed investigation. By no means should our study influence a woman to decide against a hysterectomy if her physician is recommending it. Whether you have a hysterectomy or not, your risk for Parkinson's disease remains very small."

The Mayo Clinic researchers previously found consistently higher rates of Parkinson's disease in men versus women, providing another clue to support the possible involvement of hormones in the makeup of the disease.

"In a previous study, we noted that men were one and one-half times more likely to get Parkinson's disease than women," says Dr. Maraganore. "The thought was that this is perhaps because men are in the workplace more and exposed to environmental toxins.

An alternative possibility that our study puts forward is that perhaps women are protected from Parkinson's disease by estrogen. This raises the question of whether we should be doing clinical trials of estrogen replacement therapy in postmenopausal women with Parkinson's disease or potentially one day in postmenopausal women who might otherwise be at increased risk for Parkinson's disease.

"Right now we don't know how these findings will translate to men with Parkinson's disease or men who are at increased risk for Parkinson's disease," says Dr. Maraganore. "But conceivably there may applications for men in the future."

Initial findings of this study were presented at the 1998 American Academy of Neurology meeting.