The relevance of gender in Parkinson's disease: a review.

Since the official and systematic inclusion of sex and gender in biomedical research, gender differences have been acknowledged as important determinants of both the susceptibility to develop neurodegenerative diseases in general population and the clinical and therapeutic management of neurodegenerative patients. In this review, we gathered the available evidence on gender differences in Parkinson's disease (PD) regarding clinical phenotype (including motor and non-motor symptoms), biomarkers, genetics and therapeutic management (including pharmacological and surgical treatment). Finally, we will briefly discuss the role of estrogens in determining such differences. Several data demonstrate that PD in women starts with a more benign phenotype, likely due to the effect of estrogens. However, as the disease progresses, women are at higher risk of developing highly disabling treatment-related complications, such as motor and non-motor fluctuations as well as dyskinesia, compared with men. In addition, women have lower chances of receiving effective treatment for PD as deep brain stimulation. Taken together these findings challenge the definition of a more benign phenotype in women. Still, much work needs to be done to better understand the interaction between gender, genetics and environmental factors in determining the PD risk and clinical features. Improving our understanding in this field may result in implementation of strategies to identify prodromal PD and speed efforts to discern new directions for disease tailored treatment and management.