Body mass index does not change before Parkinson's disease onset

Previous studies on the association between Parkinson's disease (PD) and body mass index (BMI) have reported conflicting results. We investigated the relationship between PD and BMI by a case-control study. PD patients were randomly matched to healthy individuals by sex and age. BMI distribution in cases has been compared with BMI of controls and odd ratios (ORs) with 95% CI were calculated. We included 318 PD patients and 318 controls. We observed no association between PD and BMI. BMI distribution in cases and controls was similar also when we adjusted for diabetes, hypercholesterolemia and the time elapsed between PD onset and the interview (OR = 0.99; CI = 0.94-1.03; P = 0.51). These results did not confirm the previously reported association between PD and BMI. Population characteristics and methodological issues may partially account for the differences observed between the present study and the others.