February 25, 2009 (Bronx, NY) Women who have more years of fertility (the time from first menstruation to menopause) have a lower risk of developing Parkinsons disease than women with fewer years, according to a large, new study by researchers at Albert Einstein College of Medicine of Yeshiva University.
These findings, involving nearly 74,000 women, suggest that longer exposure to the bodys own, or endogenous, hormones, including estrogen, may help protect the brain cells that are affected by Parkinsons disease, says lead author Rachel Saunders-Pullman, M.D., M.P.H., M.S., assistant professor of neurology at Einstein and attending physician in neurology at Beth Israel Medical Center, an affiliate of Einsteins in Manhattan.
An abstract of the study was released today by the American Academy of Neurology (AAN). Further study details will be presented at AANs 61st Annual Meeting in Seattle, April 25 - May 2, 2009.
After Alzheimers disease, Parkinsons disease is the most common neurodegenerative disease. About 1.5 million Americans currently have Parkinsons, characterized by symptoms that can include tremor (shaking), slowness of movement, rigidity (stiffness), and difficulty with balance. The condition typically develops after the age of 60, although 15 percent of those diagnosed are under 50. There is no cure for Parkinsons, although medications or surgery can ease symptoms of the disease.
Parkinsons disease is almost twice as common in men as in women, and researchers have long hypothesized that sex hormones might play a role in the disease.
In the current study, researchers analyzed the records of the Womens Health Initiative (WHI) Observational Study and focused on those women who developed Parkinsons disease. The study involved about 73,973 women who underwent natural menopause.
The study found that women who had a fertile lifespan of more than 39 years had about a 25 percent lower risk of developing Parkinsons compared with women who had a fertile lifespan shorter than 33 years.
In addition, the data showed that women who had four or more pregnancies were about 20 percent more likely to develop Parkinsons disease than were women who had three or fewer pregnancies. One explanation for this finding is that the post-partum period, which is typically one with lower levels of estrogen, subtracts from a womans total fertile lifespan, says co-author Sylvia Wassertheil-Smoller, Ph.D., professor of epidemiology and population health and the principal investigator of the WHI study at Einstein.
Overall, our findings might lead one to assume that hormone therapy would make sense as a neuroprotective agent, says Dr. Saunders-Pullman. However, we also found that women who were taking hormone therapy did not have a lower risk for Parkinsons. Thus, our data does not support a role for treatment with exogenous hormones, that is, hormones that originate outside the body, to prevent Parkinsons.
In fact, hormone therapy can have harmful neurological effects. Earlier studies in the Womens Health Initiative demonstrated that hormone therapy increases ones risk for both stroke and dementia, says Dr. Wassertheil-Smoller. Clearly, we need to conduct more research into estrogens effects on the brain.
|Contact: Deirdre Branley|
Albert Einstein College of Medicine