Hormones May Play a Role in Parkinson's
Study Shows Length of Fertility for Women May Be a Factor in Risk for Parkinson's Disease
Feb. 25, 2009 -- Women who are fertile for more than 39 years and have
natural menopause have a reduced risk of developing Parkinson's disease, according to
a new study, while women with four or more pregnancies have a higher risk.
Parkinson's disease is a movement disorder that results in slowness of
movement, impaired balance, and tremor and trembling in the extremities and
face. It affects about 1 million Americans, according to the Parkinson's
Fertile life span is the number of years from first menstruation to menopause.
"Thirty five or thirty-six years is about average," says study
researcher Rachel Saunders-Pullman, MD, MPH, assistant professor of neurology
at Albert Einstein College of Medicine and attending neurologist at Beth Israel
Medical Center, New York City.
"It does appear that hormones and reproductive factors play a role in
the development of Parkinson's disease," she says. Her study will be
presented at the American Academy of Neurology's 61st annual meeting in
Seattle, April 25-May 2.
Hormonal factors and their possible role in Parkinson's disease have been
studied for at least 15 years, says Saunders-Pullman. Parkinson's affects more
men than women, she says, with the gender ratio about two to one.
"The question is, 'Why are women at decreased risk? Is there a hormonal
role?''' she asks. "Could female hormones be protective?"
Studies have yielded conflicting results, so Saunders-Pullman and her
colleagues analyzed the records from the Women's Health Initiative
Observational Study, looking at about 74,000 women who had natural menopause
and about 7,800 who had surgical menopause.
They divided the natural menopause women into three groups and the surgical
menopause into three groups, depending on the length of the woman's fertility, and relied on self-reported data to
determine the number of cases of diagnosed Parkinson's disease.
Fertile Life Span and Parkinson's Disease
Among the findings:
- Women who had natural menopause and a fertile life span of more than 39
years had an 18% reduced risk of getting the disease compared to those women
fertile for 33 years or less before having natural menopause. No link between
fertile life span and Parkinson's disease was found in the surgical menopause
- Women who had four or more pregnancies and experienced natural menopause
had a 20% increased risk of getting Parkinson's disease compared to women who
had three or fewer pregnancies. No link between pregnancies and disease risk
was found in the surgical menopause group.
- Women who had natural menopause and used hormone therapy in the past had no
increased risk compared to never-users, nor did current users compared to
- Women who had surgical menopause and had used hormone therapy in the past
had double the risk of getting the disease compared to never-users. Current
users had no increased risk compared to never-users.