[Multidimensional evaluation of olfactory function in patients with Parkinson's disease and its correlation with rapid eye movement sleep behavior disorder].

Abstract

Objective: To analyze the application value of different dimensional olfactory tests in different dimensions of olfactory function in patients with Parkinson's disease (PD), and to explore the clinical characteristics of different olfactory dimensions in PD patients with and without rapid eye movement sleep behavior disorder (RBD) and the correlation between different olfactory dimensions and RBD. Methods: A total of 73 patients who visited the Department of Neurology, the First Affiliated Hospital of Anhui Medical University from May 2023 to June 2024 were retrospectively included. According to the Rapid Eye Movement Sleep Behavior Disorder Screening Scale (RBDSQ), PD patients were divided into 25 cases of PD with RBD (PD-RBD+) and 48 cases of PD without RBD (PD-RBD-). A total of 39 family members of patients in the same period were recruited as healthy controls. General data of all subjects were collected, and their motor symptoms, emotions, sleep status and cognitive function were evaluated. Olfactory function was evaluated by olfactory threshold, discrimination and recognition olfactory tests in three dimensions. The receiver operating characteristic (ROC) curve was used to analyze the ability of the three olfactory tests to distinguish PD patients from healthy controls.. Spearman correlation analysis was used to evaluate the correlation between different olfactory dimensions and motor and non-motor symptoms. Results: There were 39 males and 34 females in PD patients, aged (63±7) years old; there were 16 males and 23 females in healthy controls, aged (64±10) years old. The olfactory threshold [(6.92±4.20) vs (9.36±4.33), P=0.005], discrimination [(7.44±3.05) vs (10.44±3.04), P<0.001] and recognition [(15.38±5.80) vs (22.72±5.09), P<0.001] scores of PD patients were lower than those of healthy controls. ROC curve analysis of different olfactory tests to distinguish PD patients from healthy controls showed that among the three olfactory tests, the area under the curve (AUC) of the olfactory threshold test was 0.671 (95%CI: 0.568-0.773, P=0.003), the AUC of the olfactory discrimination test was 0.750 (95%CI: 0.655-0.844, P<0.001), and the AUC of the olfactory identification test was 0.829 (95%CI: 0.751-0.906, P<0.001). The olfactory recognition of the PD-RBD+group [(13.36±5.77) vs (16.44±5.58), P=0.030] was significantly lower than that of the PD-RBD-group. There were no significant differences in olfactory threshold [(6.58±3.49) vs (6.69±4.04), P=0.906] and discrimination [(7.00±3.39) vs (7.00±3.39), P=0.380] between the PD-RBD+group and the PD-RBD-group. Olfactory threshold was positively correlated with Montreal Cognitive Assessment (MoCA) (r=0.236, P=0.045); olfactory discrimination was negatively correlated with Pittsburgh Sleepiness Scale (PSQI) (r=-0.347, P=0.003); olfactory identification was positively correlated with MoCA (r=0.246, P=0.036), and negatively correlated with RBDSQ (r=-0.254, P=0.030) and PSQI (r=-0.335, P=0.004). Conclusions: The olfactory threshold, discrimination and identification abilities of PD patients are impaired. Olfactory identification test was more capable of distinguishing PD patients from healthy controls. PD-RBD+patients have worse olfactory identification ability than PD-RBD-patients. There is a significant correlation between olfactory identification and RBDSQ.