title: Body Mass Index and Risk of Parkinson's Disease: A Dose-Response Meta-Analysis of Prospective Studies.
abstract: BACKGROUND
  A number of epidemiologic studies examining the relationship between body mass index (BMI) and the future occurrence of Parkinson's disease (PD) reported largely inconsistent findings. We conducted a dose-response meta-analysis of prospective studies to clarify this association.
  
  
  METHODS
  Eligible prospective studies were identified by a search of PubMed and by checking the references of related publications. The generalized least squares trend estimation was employed to compute study-specific relative risks (RR) and 95% confidence intervals (CI) for an increase in BMI of 5 kg/m2, and the random-effects model was used to compute summary RR and 95% CI.
  
  
  RESULTS
  A total of 10 prospective studies were included in the final analysis. An increase in BMI of 5 kg/m2 was not associated with PD risk, with a summary RR of 1.00 (95% CI = 0.89-1.12). Results of subgroup analysis found similar results except for a week positive association in studies that adjusted for alcohol consumption (RR = 1.13, 95% CI = 0.99-1.29), and a week inverse association in studies that did not (RR = 0.90, 95% CI = 0.78-1.04). In a separate meta-analysis, no significant association between overweight (25 kg/m2 ≤ BMI ≤29.9 kg/m2), obesity (BMI≥30 kg/m2) or excess weight (BMI≥25 kg/m2) and PD risk was observed.
  
  
  CONCLUSIONS
  This meta-analysis does not support the notion that higher BMI materially increases PD risk. However, a week positive BMI-PD association that may be masked by confounders still cannot be excluded, and future prospective studies with a good control for potential confounding factors are needed.
authors.affiliation: Department of Neurology, the 148 Central Hospital of PLA, Zibo, 255000, China.
authors.forename: Yun-Liang
authors.initials: YL
authors.lastname: Wang
authors.affiliation: School of Medicine, Henan University, Kaifeng, 475000, China.
authors.forename: Yu-Tong
authors.initials: YT
authors.lastname: Wang
authors.affiliation: Department of Neurology, the 148 Central Hospital of PLA, Zibo, 255000, China.
authors.forename: Jin-Feng
authors.initials: JF
authors.lastname: Li
authors.affiliation: Department of Neurology, the 148 Central Hospital of PLA, Zibo, 255000, China.
authors.forename: Yu-Zheng
authors.initials: YZ
authors.lastname: Zhang
authors.affiliation: Department of Neurology, the 148 Central Hospital of PLA, Zibo, 255000, China.
authors.forename: Hong-Lei
authors.initials: HL
authors.lastname: Yin
authors.affiliation: Department of Neurology, the 148 Central Hospital of PLA, Zibo, 255000, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Han
mesh_terms: D015992:Body Mass Index; D006801:Humans; D050177:Overweight / Q000453:epidemiology; D010300:Parkinson Disease / Q000453:epidemiology*; D011446:Prospective Studies