Association of UV radiation with Parkinson's disease incidence: A nationwide French ecologic study

International audience; Meeting: 20th International Congress Abstract Number: 467 Objective: 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 exposure with Parkinson's disease (PD) incidence.

Background: In addition to regulating calcium homeostasis and bone metabolism, vitamin D is involved in multiple biological pathways.

Lower vitamin D is associated with increased mortality, in particular from cancer, and there is increasing evidence that it may play a role in brain health, including Alzheimer's disease, cognitive decline, multiple sclerosis, and PD.

Exposure of the skin to UV-B from sunlight is the most important source of vitamin D, and a good surrogate marker of vitamin D levels in population settings.

Methods: 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 including a random intercept per canton to examine its association with UV-B (2005 annual average), after adjustment for age, sex, deprivation index, smoking, proportion of agricultural land, and vitamin D supplementation.

Results: Analyses are based on 69,010 incident PD patients.

PD incidence increased with age and washigher in men than women.

The association between UV-B and PD incidence was quadratic (P<0.001) andmodified by age (P<0.001) but not by sex (P>0.15).

Below 70 years, incidence was higher in the bottomquintile (RR-Q1-45-49y=1.209, 95% CI= 1.108-1.320) compared with the middle UV-B quintile, and lowerin the top quintile (RR-Q5-45-49y=0.883 [0.802-0.972]).

The opposite pattern was observed in oldersubjects (RR-Q1-85-89y=0.941 [0.903-0.981]; RR-Q5-85-89y=1.102 [1.057-1.150]).

Analyses based oncontinuous UV-B yielded similar conclusions.Conclusions: In this nationwide ecologic study, there was an age-dependent quadratic association betweenUV-B and PD incidence.

This study suggests that low UV-B exposure is associated with higher PD risk inyounger persons, but not in older persons, and that future studies should examine dose-response relationsand take age into account.