title: Physical activity and risk of Parkinson's disease in the Swedish National March Cohort.
abstract: Physical exercise has been associated with neuroprotective effects in the nigrostriatal dopaminergic system. To examine the impact of physical activity on Parkinson's disease risk prospectively, we followed 43 368 individuals who provided extensive information on physical activity at baseline. We estimated hazard ratios with 95% confidence intervals using Cox proportional hazards regression. During an average of 12.6 years of follow-up, 286 incident Parkinson's disease cases were identified. In males, there was an inverse association with Parkinson's disease for total physical activity (hazard ratio 0.55, 95% confidence interval 0.35-0.87 for medium versus low level), for sum of household, commuting and leisure time exercise (hazard ratio 0.53, 95% confidence interval 0.33-0.85 for high versus low level), and for household and commuting physical activity specifically (hazard ratio 0.50, 95% confidence interval 0.31-0.81 for >6 versus <2 h per week). No association was observed for leisure time exercise or occupational physical activity with Parkinson's disease, among either males or females. Meta-analysis of the present study and five previous prospective studies showed a pooled hazard ratio of 0.66 (95% confidence interval 0.57-0.78) for highest versus lowest physical activity level. Our results indicate that a medium level of physical activity lowers Parkinson's disease risk.
authors.affiliation: 1 Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, 17177 Stockholm, Sweden fei.yang@ki.se.
authors.forename: Fei
authors.initials: F
authors.lastname: Yang
authors.affiliation: 2 Department of Medicine, Unit of Clinical Epidemiology, Karolinska Institutet, T2, 17176 Stockholm, Sweden.
authors.forename: Ylva
authors.initials: Y
authors.lastname: Trolle Lagerros
authors.affiliation: 1 Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, 17177 Stockholm, Sweden 3 Department of Statistics and Quantitative Methods, University of Milano-Bicocca, Milan, Italy.
authors.forename: Rino
authors.initials: R
authors.lastname: Bellocco
authors.affiliation: 1 Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, 17177 Stockholm, Sweden 4 Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA.
authors.forename: Hans-Olov
authors.initials: HO
authors.lastname: Adami
authors.affiliation: 1 Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, 17177 Stockholm, Sweden.
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.affiliation: 1 Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, 17177 Stockholm, Sweden 5 Department of Psychology, University of Southern California, Los Angeles, CA 90089-1061, USA.
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Pedersen
authors.affiliation: 1 Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, 17177 Stockholm, Sweden 6 Department of Clinical Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Wirdefeldt
mesh_terms: D000367:Age Factors; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007899:Leisure Activities; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D010300:Parkinson Disease / Q000453:epidemiology*; D011446:Prospective Studies; D012306:Risk; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology
keywords: Parkinson’s disease; cohort studies; epidemiology; exercise; meta-analysis