Sex differences in Parkinson’s disease: Features on clinical symptoms, treatment outcome, sexual hormones and genetics

•Sex is a significant factor in the development of Parkinson’s disease.•Sex differences have been reported in motor and non-motor symptoms and treatment outcome.•Sex differences in Parkinson’s disease are determined by biological sex differences.•Y chromosome- associated genes and sexual hormones contribute to sex differences in mitochondria and neuroinflammation.•Sex hormones contribute to sex differences in the action of other genetic factors. Parkinson’s disease (PD) is the second most frequent age-related neurodegenerative disorder. Sex is an important factor in the development of PD, as reflected by the fact that it is more common in men than in women by an approximate ratio of 2:1. Our hypothesis is that differences in PD among men and women are highly determined by sex-dependent differences in the nigrostriatal dopaminergic system, which arise from environmental, hormonal and genetic influences. Sex hormones, specifically estrogens, influence PD pathogenesis and might play an important role in PD differences between men and women. The objective of this review was to discuss the PD physiopathology and point out sex differences in nigrostriatal degeneration, symptoms, genetics, responsiveness to treatments and biochemical and molecular mechanisms among patients suffering from this disease. Finally, we discuss the role estrogens may have on PD sex differences.