title: Association of UV radiation with Parkinson disease incidence: A nationwide French ecologic study.
abstract: Vitamin D is thought to contribute to brain health, but it is unclear whether low vitamin D levels are associated with increased incidence of Parkinson's disease (PD). Using ultraviolet B (UV-B) as a surrogate for vitamin D levels, we conducted a nationwide ecologic study in France in order to examine the association of UV-B with PD incidence.
  
  
  
  We used French national drug claims databases to identify PD cases using a validated algorithm. UV-B data from the solar radiation database were derived from satellite images. We estimated PD incidence (2010-2012) at the canton level (small administrative French unit) and used multilevel Poisson regression to examine its association with UV-B (2005 annual average), after adjustment for age, sex, deprivation index, density of neurologists, smoking, proportion of agricultural land, and vitamin D supplementation.
  
  
  
  Analyses are based on 69,010 incident PD patients. The association between UV-B and PD incidence was quadratic (P<0.001) and modified by age (P<0.001). Below 70y, incidence was higher in the bottom quintile (relative risk, RRQ1:45-49y=1.18, 95% CI=1.08-1.29) compared with the middle UV-B quintile, and lower in the top quintile (RRQ5:45-49y=0.85 [0.77-0.94]). An opposite pattern was observed in older subjects (RRQ1:85-89y=0.92 [0.89-0.96]; RRQ5:85-89y=1.06 [1.02-1.11]). Analysis based on continuous UV-B yielded similar conclusions.
  
  
  
  In this nationwide study, there was an age-dependent quadratic association between UV-B and PD incidence. This study suggests that reasonable UV-B exposure is associated with lower PD risk in younger persons and that future studies should examine dose-response relations and take age into account.
authors.affiliation: University of Miami Miller School of Medicine, Miami, Florida, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Kravietz
authors.affiliation: Santé publique France, Direction santé travail, F-94415 Saint-Maurice, France; CESP, Fac. de médecine - Univ. Paris-Sud, Fac. de médecine - UVSQ, INSERM, Université Paris-Saclay, 94805 Villejuif, France.
authors.forename: Sofiane
authors.initials: S
authors.lastname: Kab
authors.affiliation: MINES ParisTech, PSL Research University, Sophia Antipolis, France.
authors.forename: Lucien
authors.initials: L
authors.lastname: Wald
authors.affiliation: CESP, Fac. de médecine - Univ. Paris-Sud, Fac. de médecine - UVSQ, INSERM, Université Paris-Saclay, 94805 Villejuif, France.
authors.forename: Aline
authors.initials: A
authors.lastname: Dugravot
authors.affiliation: CESP, Fac. de médecine - Univ. Paris-Sud, Fac. de médecine - UVSQ, INSERM, Université Paris-Saclay, 94805 Villejuif, France; Department of Epidemiology and Public Health, University College London, London, UK.
authors.forename: Archana
authors.initials: A
authors.lastname: Singh-Manoux
authors.affiliation: Santé publique France, Direction santé travail, F-94415 Saint-Maurice, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Moisan
authors.affiliation: Santé publique France, Direction santé travail, F-94415 Saint-Maurice, France; CESP, Fac. de médecine - Univ. Paris-Sud, Fac. de médecine - UVSQ, INSERM, Université Paris-Saclay, 94805 Villejuif, France. Electronic address: alexis.elbaz@inserm.fr.
authors.forename: Alexis
authors.initials: A
authors.lastname: Elbaz
mesh_terms: D000368:Aged; D019587:Dietary Supplements; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000453:epidemiology*; D012307:Risk Factors; D013472:Sunlight; D014466:Ultraviolet Rays; D014807:Vitamin D / Q000008:administration & dosage
chemical_list: D014807:Vitamin D
keywords: Incidence; Parkinson's disease; Ultraviolet; Vitamin D