Does Coffee Prevent Parkinson's Disease? -- An Overview
Many people wonder if coffee, tea, and other caffeine products could possibly increase or decrease the risk for developing chronic conditions, including Parkinson's disease
. The answer to the Parkinson's disease question is still not known for certain, although the most current research supports the claim that coffee and tea can provide some protection from developing Parkinson's disease.
Understanding the Research on Parkinson's Disease and Coffee/Tea
Several large studies have shown that caffeine intake is associated with a reduced risk of developing Parkinson's disease in men. For example, one large study found an annual incidence rate of 10.5 cases of Parkinson's disease per 10,000 person-years (one year of life for one person) among non-coffee drinkers. The incidence rate dropped to 5.5 for those drinking 4 to 8 ounces of coffee per day, 4.7 for those drinking 12 to 16 ounces, 3.6 for those drinking 20 to 24 ounces, and 1.7 for those drinking more than 28 ounces.
Adjusting for other factors, the researchers estimated that non-coffee drinkers were two to three times as likely to develop Parkinson's disease as coffee drinkers consuming 4 to 24 ounces per day. When compared to men who drank the highest amount of coffee (28 ounces or more per day), nondrinkers were five times as likely to develop Parkinson's disease. These rates include an adjustment by the researchers to account for cigarette smoking, a previously identified protective agent for Parkinson's disease.
Up until recently, studies in women looking at the impact of coffee and Parkinson's disease have been inconclusive. This may be partly because of when these studies were done and how many women in these studies were also taking hormone replacement therapy
) to treat menopause symptoms
A recent study shows that hormone therapy is a possible explanation for the different effects of caffeine on Parkinson's disease risk in men and women. The study shows that postmenopausal women who took hormone replacement therapy (HRT) and drank more than five cups of coffee per day (heavy coffee drinkers) were one and a half times more likely to develop Parkinson's disease than heavy coffee drinkers who didn't take HRT.
Taking coffee out of the equation, HRT seemed to have a protective effect against Parkinson's disease; these results support those of earlier studies. Women who drank little or no coffee and took HRT had 65 percent less risk of developing Parkinson's disease than light coffee drinkers who didn't take HRT.
The researchers studied survey data from more than 77,000 nurses who participated in the Nurses' Health Study, a comprehensive 20-year study designed to take a closer look at women's health. In this group, 154 women were diagnosed with Parkinson's disease during the study. Overall, there was no difference in disease incidence between women who were and weren't using HRT. However, when caffeine consumption was factored in, HRT made a big difference in the person's risk of developing Parkinson's disease.
Among women taking HRT, the increased risk of Parkinson's disease was confined to women who drank more than five cups of coffee per day. Drinking small amounts of coffee per day did not appear to affect the risk of Parkinson's disease in these women. The type of hormones and the duration of use did not seem to affect outcomes. The researchers noted that they controlled for possible effects of cigarette smoking, which has repeatedly been shown to be associated with a decreased risk of Parkinson's disease.