Olfactory Dysfunction and Its Association With Neuropathologic Proteins in Cerebrospinal Fluid From Patients With Parkinson Disease

• Main Authors: Peng Guo, Rui-dan Wang, Teng-hong Lian, Du-yu Ding, Ya-nan Zhang, Wei-Jiao Zhang, Dan-ning Li, Li-xia Li, Jing-hui Li, Hui-ying Guan, Shu-yang Yu, Li Liu, Yang Hu, Li-jun Zuo, Qiu-jin Yu, Xiao-min Wang, Wei Zhang
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2020-12-01
• Series: Frontiers in Aging Neuroscience
• Subjects: Parkinson disease; olfactory dysfunction; sniffin' sticks test; cerebrospinal fluid; neuropathologic proteins
• Online Access: https://www.frontiersin.org/articles/10.3389/fnagi.2020.594324/full

Background and Purpose: Olfactory dysfunction (OD) is a common non-motor symptom of Parkinson disease (PD). However, the relationship between OD and neuropathologic proteins in cerebrospinal fluid (CSF) from PD patients remains unclear.Methods: 166 PD patients were included in the study. Overall olfactory function was assessed by summing up the scores of olfactory threshold, discrimination, and identification by a Sniffin' Sticks test, based on which, patients were divided into PD with OD (PD-OD) and PD with no OD (PD-NOD) groups. CSF samples were obtained from 76 PD patients. The levels of neuropathologic proteins, including α-Synuclein, Aβ1-42, total tau (T-tau), and multiple forms of phosphorylated tau (P-tau) in CSF were measured by an enzyme-linked immunosorbent assay.Results: out of the 166 PD patients, 103 cases (62.0%) had OD. The scores of overall olfactory functions, and olfactory threshold, discrimination, and identification in the PD-OD group were all significantly lower than that in the PD-NOD group (P < 0.001). α-Synuclein level in CSF was significantly higher in the PD-OD group than the PD-NOD group (P < 0.05), and was significantly and negatively correlated with the scores of overall olfactory function, and olfactory discrimination and identification (P < 0.05). Aβ1-42 level in CSF was higher in the PD-OD group than the PD-NOD group, and was significantly and negatively correlated with the olfactory identification score (P < 0.05). T-tau level in CSF was significantly lower in the PD-OD group than the PD-NOD group (P < 0.05), and was significantly and positively correlated with the olfactory discrimination score (P < 0.05). There was no significant difference in P-tau level in CSF between the PD-OD and PD-NOD groups and no correlation between OD score and P-tau level in CSF.Conclusions: PD-OD includes the impairments of olfactory threshold, discrimination, and identification, and is associated with the significant elevation of α-Synuclein and the decrease of the T-tau level in CSF.