Case-control study of risk of Parkinson's disease in relation to hypertension, hypercholesterolemia, and diabetes in Japan

This case-control study investigated the associations of a history of hypertension, hypercholesterolemia, and diabetes mellitus with the risk of Parkinson's disease (PD) in Japan. Included were 249 cases within 6 years of onset of PD. Controls were 368 inpatients and outpatients without a neurodegenerative disease. Data on the vascular risk factors and confounders were obtained from a self-administered questionnaire. The vascular risk factors were defined based on drug treatment. Adjustment was made for sex, age, region of residence, pack-years of smoking, years of education, leisure-time exercise, body mass index, dietary intake of energy, cholesterol, vitamin E, alcohol, and coffee and the dietary glycemic index. The proportions of hypertension, hypercholesterolemia, and diabetes mellitus prior to the onset of PD were 23.7%, 9.6%, and 4.0%, respectively, in cases. Hypertension, hypercholesterolemia, and diabetes mellitus were significantly associated with a decreased risk of PD: the adjusted ORs were 0.43 (95% CI: 0.29-0.64), 0.58 (95% CI: 0.33-0.97), and 0.38 (95% CI: 0.17-0.79), respectively. No significant differences were observed in the association of vascular risk factors with the risk of PD between men and women. We found evidence of significant inverse associations of hypertension, hypercholesterolemia, and diabetes mellitus with the risk of PD in Japan. Further well-designed investigations of the association of vascular risk factors with the risk of PD are needed, particularly large-scale prospective studies in Asia.