Serum levels of p-tau181 in patients with Parkinson’s disease
Authors: Tian Zhanglin , Bo Long , Mi Xiong , Dong Yuhan , Wei Youdong 
Published: April 2023

Background: Parkinson’s disease (PD) is the second most common neurodegenerative disease. Evidence has shown that phosphorylated tau-181 (p-tau181) is involved in the pathological process of PD. The goal of this study was to investigate the changes of serum phosphorylated Microtubule-associated protein tau at threonine-181 in patients with Parkinson's disease and it's correlation with disease severity, cognitive impairment and prognosis. Methods: A total of 40 patients with primary Parkinson's disease who were hospitalized or outpatient in the First Affiliated Hospital of Chongqing Medical University from July 2021 to February 2022 were selected as the study subjects. Patients with secondary Parkinson's disease, Parkinson's syndrome, stroke, Alzheimer's disease, craniocerebral surgery or trauma, severe systemic or infectious diseases, local or systemic infectious diseases, motor neurone disease or other central nervous system diseases were excluded. In addition, 35 healthy subjects with similar age and gender matching were selected as the healthy control group. Age, gender, course of disease, Hoehn-Yahr (H-Y) scale, Unified Parkinson's Disease Scale (UPDRS), and MoCA score were recorded in the Parkinson's disease group. According to the H-Y scale, PD group was divided into PD patients in the advanced stage (H-Y≤2.5, n=16) and PD patients in the advanced stage (H-Y>2.5, n=24). Six months after blood sample collection, we assessed the H-Y rating and UPDRS score in the Parkinson's group again by telephone follow-up. Those with decreased or unchanged H-Y rating or total UPDRS score were divided into good prognosis group (n=25), and those with increased H-Y rating or total UPDRS score were divided into poor prognosis group (n=14). The serum p-tau181 concentration of all subjects was detected and compared by double-antibody sandwich enzyme-linked immunosorbent assay (ELISA), and the correlation between serum p-tau181 level and UPDRS score, MoCA score and prognosis of Parkinson's disease patients was analyzed. Results: Compared with HC, serum p-tau181 concentration in PD patients were higher, but not statistically significant (1.01[0.28-2.63]vs 0.53[0.04-3.72]ug/mL, P=0.55, P>0.05). There was no significant difference in p-tau181 concentration between PD patients in early stage and PD patients in advanced stage (P=0.80 P>0.05), and no significant difference in p-tau181 level between PD patients with cognitive impairment, PD patients with normal cognition and HC patients (P=0.63, p>0.05). P-tau181 was not significantly correlated with disease duration (r=-0.14, P=0.37, P>0.05), UPDRS score (r=0.02, P=0.89, P>0.05), and MoCA score (r= 0.16, P=0.32, P > 0.05). There was no significant difference in serum P-tau181 expression between good prognosis group and poor prognosis group (P=0.74, P > 0.05). Conclusions: Serum expression of p-tau181 increased in PD patients, but no statistical difference was observed, and no clear correlation was found between p-tau181 and disease severity and cognitive impairment. Serum p-tau181 level in PD patients has no significant prognostic significance.