title: Lifetime occupational and leisure time physical activity and risk of Parkinson's disease.
abstract: While regular exercise has been shown to alleviate the motor symptoms of Parkinson's disease (PD), it remains unclear whether a physically active lifestyle may prevent PD.
  
  
  
  To examine physical activities across the lifespan and risk of PD, we relied on data from a population-based case-control study that enrolled 357 incident PD cases and 341 controls. We assessed physical activity levels via self-report of (1) overall physical activity (PA) over 4 age periods; (2) competitive sports; and (3) occupational histories.
  
  
  
  PD risks were lower comparing the overall PA highest quartile (moderate to vigorous activities ≥180 metabolic equivalent task-hours/week (MET-h/wk)) with the lowest quartile (<47.8 MET-h/wk) in age-period 18-24 years (adjusted odds ratio (OR) 0.64, 95% confidence interval (CI) 0.40-1.02), and 45-64 years (OR 0.50, 95%CI 0.31-0.83) but not in age-period 25-44. Individuals who consistently engaged in overall PA at high levels (before age 65 years) had a 51% lower PD risk than those with low levels. Also, having participated in competitive sports prior to age 25 was inversely associated with PD (OR 0.53, 95% CI 0.31-0.91 for high level versus never). There was no association for measures of occupational physical activity though.
  
  
  
  The long prodromal stage of PD makes it difficult to conclude whether insidious disease leads to a reduction of physical activity years before motor symptom onset and PD diagnosis. However, sports activities and high levels of overall PA in youth appear protective unless they are markers for biologic or genetic factors that lower PD risk.
authors.affiliation: Department of Epidemiology, Fielding School of Public Health, University of California at Los Angeles, California, USA.
authors.forename: I-Fan
authors.initials: IF
authors.lastname: Shih
authors.affiliation: Department of Epidemiology, Fielding School of Public Health, University of California at Los Angeles, California, USA.
authors.forename: Zeyan
authors.initials: Z
authors.lastname: Liew
authors.affiliation: Department of Epidemiology, Fielding School of Public Health, University of California at Los Angeles, California, USA; Department of Environmental Health Sciences, Fielding School of Public Health, University of California at Los Angeles, California, USA.
authors.forename: Niklas
authors.initials: N
authors.lastname: Krause
authors.affiliation: Department of Epidemiology, Fielding School of Public Health, University of California at Los Angeles, California, USA; Department of Neurology, School of Medicine, University of California at Los Angeles, California, USA. Electronic address: britz@ucla.edu.
authors.forename: Beate
authors.initials: B
authors.lastname: Ritz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002140:California / Q000453:epidemiology; D016022:Case-Control Studies; D015444:Exercise; D005260:Female; D006801:Humans; D007899:Leisure Activities; D008297:Male; D010300:Parkinson Disease / Q000453:epidemiology*; D018570:Risk Assessment / Q000706:statistics & numerical data*; D013177:Sports / Q000706:statistics & numerical data*
keywords: Exercise; Occupations; Parkinson's disease; Physical activity