Season of birth and Parkinson's disease: possible relationship?

The amount of sun exposure in early life and consequent vitamin D3 level may influence the risk of developing Parkinson's disease (PD). Yet few studies have previously investigated birth trends in PD related to a possible seasonality and sun exposure. The aim of this study was to investigate a possible relationship between PD risk and sun exposure looking at seasonal birth variation of PD subjects in the homogenous geographic area of Naples, Italy. We selected 898 PD subjects and matched with 1796 controls. McNemar's test with Bonferroni correction and autocorrelation were used to test seasonality in birth trends. No difference was found for the month and season of birth between PD subjects and controls. We found a 3.3 % increase of PD female subjects born in September (3.3 %) and 4.1 % increase of PD male subjects born in spring comparing to controls but were not significant after Bonferroni correction. This study evaluated for the first time the seasonal birth trends in relation to PD risk in a Southern European population. We found no association between seasonal birth variations and risk of PD.