Gender differences in olfactory function in patients with Parkinson's disease.

Introduction: Previous studies reported the presence of gender-related differences in motor and non motor symptoms in patients affected by Parkinson's disease (PD) (1, 2). However, gender-related differences in olfactory function are not clearly investigated. Objective: To assess the presence of gender-related differences in olfactory function among patients with PD compared to age and sex matched healthy controls. Methods: One hundred and sixty eight participants were enrolled (99 PD patients, 57 males and 42 females and 69 healthy controls, 31 males and 38 females). Olfactory function was evaluated with odor threshold, discrimination, identification and their sum TDI score by the Sniffin’ Sticks tests (3). The Montreal Cognitive Assessment (MoCA) was used to assess cognitive impairment. Apathy was examined by the Starkstein Apathy Scale (SAS) and fatigue was evaluated by the Parkinson’s Disease Fatigue Scale (PFS). Data are presented as mean values ± standard error mean. Results: Male PD patients showed a significant impairment compared to female PD patients in odor discrimination (8.4 ± 0.420 vs 7.1 ± 0.408, p<0.05), odor identification (8.6 ± 0.454 vs 7 ± 0.420, p<0.05) and in TDI score (19.9 ± 0.920 vs 16.73 ± 0.919, p<0.05). As regards odor threshold, no significant differences were observed between males and females. Moreover, no gender related differences were observed in olfactory function among healthy controls. Multivariate linear regression analyses showed that apathy and gender were the most important predictors related to the impairment of olfactory function in PD patients. Conclusions: A specific gender difference in olfactory dysfunctions among PD patients were observed only for odor discrimination, identification and TDI score. These findings highlighted the possible role of gender differences in the development of associated PD non motor symptoms. References 1) Solla et al. J Neurol Sci. 2012. 323(1-2):33-9 2) Picillo et al. J Neurol. 2013. 260(11):2849-55 3) Hummel et al. Eur Arch Otorhinolaryngol. 2007. 264(3):237–243.