Female gender but not cigarette smoking delays the onset of Parkinson's disease

ObjectiveCigarette smoking has been proposed as a protective factor against Parkinson's disease (PD); however it is not known whether smoking also delays its onset.MethodsWe conducted a long-term study of 247 patients with idiopathic PD to determine whether smoking and other factors influence its onset and development.ResultsThe mean age at disease onset was 57 ± 9 years. In smokers, the intensity and age at which exposure occurred did not modify the beginning of symptoms. Only female gender (p = 0.005) and low educational level (p = 0.03) showed a statistical association in the multivariate analysis with a delayed onset of symptoms.ConclusionOur results suggest that females have a delayed onset of symptoms, possibly related to the gonadotropin profile of our population upon the nigrostriatal dopaminergic system. The effect of low educational level may be related to a delayed diagnosis, rather than a true delay of disease onset. This report suggests an influence of gender on the onset of Parkinson's disease.