{mosimage}Women who undergo unilateral or bilateral oophorectomy prior to menopause appear to be at increased risk of parkinsonism, investigators at Mayo Clinic College of Medicine, Rochester, Minnesota, report.
Numerous animal studies have indicated estrogenic neuroprotection in the nigrostriatal pathway associated with reduced risk for Parkinson's disease, Dr. W. A. Rocca and associates note in the January 15th issue of Neurology, but evidence from clinical and epidemiologic studies has been inconclusive.
To provide more insight into these issues, they studied the effect of oophorectomy prior to menopause onset. The case-control study included premenopausal women who had undergone unilateral oophorectomy (n= 1252) or bilateral oophorectomy (n = 1075), and 2368 age-matched controls. All of the women were born before 1962, and surgery was performed between 1950 and 1987 for indications other than ovarian cancer or other estrogen-related cancer.
The risk of parkinsonism was significantly increased following oophorectomy (hazard ratio 1.68), with a trend toward increased risk with younger age at surgery.
"The findings were similar regardless of the indication for the oophorectomy, and for unilateral or bilateral oophorectomy considered separately," the investigators write.
They suggest that the premature estrogen deficiency caused by the removal of the ovaries robs neurons of the protective benefits associated with the hormone, thereby raising the risk of parkinsonism and other neurologic disorders.
"This study is one of the first to support the hypothesis of a critical age window for the protective effect of estrogen on the nigrostriatal pathway in humans," Dr. Rocca's team points out. "However, independent replication of our findings is needed before they can be considered in guiding gynecological practices."
Neurology 2008;70:200-209.
