title: Dietary glycemic index is inversely associated with the risk of Parkinson's disease: a case-control study in Japan.
abstract: OBJECTIVE
  High glycemic index (GI) or glycemic load (GL) carbohydrates might be expected to decrease the risk of Parkinson's disease (PD) by an insulin-induced increase in brain dopamine. We conducted a hospital-based case-control study in Japan to examine associations between dietary GI and GL and other dietary carbohydrate variables, including intake of available carbohydrate and dietary fiber, and PD.
  
  
  METHODS
  Patients with PD diagnosed using the U.K. Parkinson's Disease Society Brain Bank criteria (n=249) and controls without neurodegenerative diseases (n=368) were recruited. Dietary intake during the preceding month was assessed at the time of study recruitment using a validated, self-administered, semiquantitative, comprehensive diet history questionnaire.
  
  
  RESULTS
  After adjustment for potential dietary and non-dietary confounding factors, dietary GI was significantly inversely associated with the risk of PD. Multivariate odds ratios (95% confidence intervals) for PD in the first, second, third, and fourth quartiles of dietary GI were 1.00 (reference), 1.03 (0.64-1.66), 0.68 (0.41-1.15), and 0.61 (0.34-1.09), respectively (P for trend=0.04). Conversely, no significant association was observed for other dietary carbohydrates, including dietary GL (P for trend=0.77), available carbohydrate intake (P for trend=0.28), or dietary fiber intake (P for trend=0.73).
  
  
  CONCLUSIONS
  This preliminary case-control study based on current dietary habits found an independent inverse relation between dietary GI and PD. Considering the plausibility of the putative mechanism, further investigation using a case-control design with accurate assessment of past dietary habits or a prospective design is warranted.
authors.affiliation: Department of Social and Preventive Epidemiology, School of Public Health, the University of Tokyo, Tokyo, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Murakami
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Miyake
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sasaki
authors.forename: Keiko
authors.initials: K
authors.lastname: Tanaka
authors.forename: Wakaba
authors.initials: W
authors.lastname: Fukushima
authors.forename: Chikako
authors.initials: C
authors.lastname: Kiyohara
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Tsuboi
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Yamada
authors.forename: Tomoko
authors.initials: T
authors.lastname: Oeda
authors.forename: Takami
authors.initials: T
authors.lastname: Miki
authors.forename: Nobutoshi
authors.initials: N
authors.lastname: Kawamura
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Sakae
authors.forename: Hidenao
authors.initials: H
authors.lastname: Fukuyama
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Hirota
authors.forename: Masaki
authors.initials: M
authors.lastname: Nagai
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D004032:Diet; D015930:Diet Records; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004043:Dietary Fiber; D005260:Female; D038321:Glycemic Index; D006761:Hospitals; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010300:Parkinson Disease / Q000453:epidemiology*; D012307:Risk Factors; D011795:Surveys and Questionnaires
chemical_list: D004040:Dietary Carbohydrates; D004043:Dietary Fiber