title: Dose-dependent protective effect of coffee, tea, and smoking in Parkinson's disease: a study in ethnic Chinese.
abstract: BACKGROUND
  Few studies have examined the relationship of coffee and tea in Parkinson's disease (PD). The potential protective effect of coffee intake and risk of PD has not been studied in a Chinese population. There is a high prevalence of caffeine takers among Chinese in our population.
  
  
  OBJECTIVE
  We undertook a case control study to examine the relationship between coffee and tea drinking, cigarette smoking, and other enviromental factors and risk of PD among ethnic Chinese in our population.
  
  
  RESULTS
  300 PD and 500 population controls were initially screened. Two hundred case control pairs matched for age, gender, and race were finally included in the analysis. Univariate analysis revealed significant association of PD with coffee drinking (p<0.0005), tea drinking (p=0.019), alcohol drinking (p=0.001), cigarette smoking (p<0.0005), and exposure to heavy metals (p=0.006). Conditional logistic regression analysis demonstrated that amount of coffee drunk (OR 0.787, 95%CI 0.664-0.932, p=0.006), amount of tea drunk (OR 0.724, 95%CI 0.559-0.937, p=0.014), number of cigarettes smoked (OR 0.384, 95%CI 0.204-0.722, p=0.003), history of heavy metal and toxin exposure (OR 11.837, 95%CI 1.075-130.366, p=0.044), and heart disease (OR 5.518, 95%CI 1.377-22.116, p=0.016) to be significant factors associated with PD. One unit of coffee and tea (3 cups/day for 10 years) would lead to a 22% and 28% risk reduction of PD. One unit of cigarette smoke (3 packs/day for 10 years) reduced the risk of PD by 62%.
  
  
  CONCLUSIONS
  We demonstrated a dose-dependent protective effect of PD in coffee and tea drinkers and smokers in an ethnic Chinese population. A history of exposure to heavy metals increased the risk of PD, supporting the multifactorial etiologies of the disease.
authors: Department of Neurology, Singapore General Hospital, Singapore. gnrtek@sgh.com.sg
authors: E-K
authors: EK
authors: Tan
authors: C
authors: C
authors: Tan
authors: S M C
authors: SM
authors: Fook-Chong
authors: S Y
authors: SY
authors: Lum
authors: A
authors: A
authors: Chai
authors: H
authors: H
authors: Chung
authors: H
authors: H
authors: Shen
authors: Y
authors: Y
authors: Zhao
authors: M L
authors: ML
authors: Teoh
authors: Y
authors: Y
authors: Yih
authors: R
authors: R
authors: Pavanni
authors: V R
authors: VR
authors: Chandran
authors: M C
authors: MC
authors: Wong
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D002110:Caffeine / Q000494:pharmacology; D016022:Case-Control Studies; D002681:China / Q000208:ethnology; D003069:Coffee / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D006801:Humans; D008297:Male; D019216:Metals, Heavy / Q000009:adverse effects; D008875:Middle Aged; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009538:Nicotine / Q000494:pharmacology; D016017:Odds Ratio; D010300:Parkinson Disease / Q000453:epidemiology / Q000208:ethnology / Q000517:prevention & control*; D012307:Risk Factors; D012846:Singapore / Q000453:epidemiology; D012907:Smoking / Q000453:epidemiology / Q000378:metabolism*; D013223:Statistics as Topic; D013662:Tea / Q000378:metabolism*
chemical_list: D003069:Coffee; D019216:Metals, Heavy; D018696:Neuroprotective Agents; D013662:Tea; D002110:Caffeine; D009538:Nicotine