Sex specific cognitive differences in Parkinson disease

Parkinson disease (PD) is a progressive neurodegenerative disorder that is 1.5 times more common in males than in females. While motor progression tends to be more aggressive in males, little is known about sex difference in cognitive progression. We tested the hypothesis that there are sex differences in cognitive dysfunction in non-demented PD. We evaluated 84 participants (38 females) with PD and 59 controls (27 females) for demographic variables and cognitive function, including attention, working memory, executive function, and processing speed. Multivariate ANOVA revealed no significant differences between groups for demographic variables, including age, years of education, global cogntition, daytime sleepiness, predicted premorbid IQ, UPDRS score, PD phenotype, or disease duration. For cognitive variables, we found poorer performance in males versus females with PD for measures of executive function and processing speed, but no difference between male and female controls. Specifically, PD males showed greater deficits in Verbal Fluency (category fluency, category switching, and category switching accuracy), Color Word Interference (inhibition), and speed of processing (SDMT). There were no differences in measures of working memory or attention across sex and inconsistent findings for switching. Our data indicate that males with PD have significantly greater executive and processing speed impairments compared to females despite no differences in demographic variables or other measures of disease severity. Our findings are consistent with the steeper slope of disease progression reported in males with PD.