Caffeine and estrogen affect disease risk in postmenopausal women.(Parkinson disease risk)

2003 APR 3 - (NewsRx.com & NewsRx.net) -- Women who consume little or no caffeine, but who take hormone replacement therapy (HRT), may reduce their risk of developing Parkinson disease, according to a new study. However, HRT may increase disease risk in women who drink the equivalent of more than five cups of coffee per day.

Two large studies have previously shown that increased caffeine intake is associated with a lower risk of Parkinson disease in men. Studies in women, which to date have not factored in use of hormone replacement therapy, have been contradictory and inconclusive. Parkinson disease is less common in women, and some evidence suggests that estrogen may help protect the neurons that degenerate in this disease. Estrogen is the principal hormone in HRT, a common therapy in postmenopausal women.

Eighteen years of data from more than 77,000 women were drawn from the Nurses' Health Study. Information on hormone use and caffeine intake was collected from survey data. Study results were published in the March 11, 2003 issue of Neurology.

Parkinson disease was diagnosed in 154 of the women during the study. Similar to some previous studies, there was no difference in the incidence of disease between women who did or did not use HRT, when that was the only variable considered. However, when caffeine consumption was also factored in, some unexpected results emerged. In women who drank less than half a cup of coffee per day, HRT use was associated with a 65% reduction in relative risk of developing Parkinson disease, compared to those who did not use HRT. These results are in keeping with the hypothesis that estrogen may help protect women against the brain cell death that causes Parkinson disease. However, at the other extreme, in women who drank the equivalent of more than five cups per day, HRT seemed to have the ...