Prospective study of caffeine consumption and risk of Parkinson's disease in men and women

Results of case-control studies and of a prospective investigation in men s uggest that consumption of coffee could protect against the risk of Parkins on's disease, but the active constituent is not dear. To address the hypoth esis that caffeine is protective against Parkinson's disease, we examined t he relationship of coffee and caffeine consumption to the risk of this dise ase among participants in two ongoing cohorts, the Heath Professionals' Fol low-Up Study (HPFS) and the Nurses' Heath Study (NHS), The study population comprised 47,351 men and 88,565 women who were free of Parkinson's disease , stroke, or cancer at baseline. A comprehensive life style and dietary que stionnaire was completed by the participants at baseline and updated every two to four years. During the follow-lip (10 years in men, 16 years in wome n), we documented a total of 288 incident cases of Parkinson's disease. Amo ng men, after adjustment for age and smoking, the relative risk of Parkinso n's disease was 0.42 (95% CI: 0.23-0.78; P for trend < 0.001) for men in th e top one-fifth of caffeine intake compared to those in the bottom one-fift h. An inverse association was also observed with consumption of coffee (p f or trend = 0.004), caffeine from noncoffee sources (p for trend < 0.001), a nd tea (p for trend = 0.02) but not decaffeinated coffee. Among women, the relationship between caffeine or coffee intake and risk of Parkinson's dise ase was U-shaped, with the lowest risk observed at moderate intakes (1-3 cu ps of coffee/day, or the third quintile of caffeine consumption). These res ults support a possible protective effect of moderate doses of caffeine on risk of Parkinson's disease.