Associations of blood UCH-L1 and NfL levels with cognitive dysfunction in Parkinson’s disease patients

Ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) and Neurofilament light chain (NfL) are associated with Lewy body formation, Lewy bodies are the main pathological feature of Parkinson's disease (PD). The relationship between UCH-L1 and PD cognition remains unclear, and NfL is an important marker of cognitive impairment. The aim of this study is to investigate the relationship among serum UCH-L1 levels, plasma NfL levels and cognitive dysfunction in PD patients.There were significant differences in UCH-L1 and NfL levels among PD patients with normal cognitive function (PD-CN), PD patients with mild cognitive impairment (PD-MCI), and PD-dementia patients (PDD) (P < 0.001; P < 0.001). The PDD group had lower levels of UCH-L1 (Z = 6.721, P < 0.001; Z = 7.577, P < 0.001) and higher levels of NfL (Z = -3.626, P = 0.001; Z = -2.616P = 0.027) than the PD-NC and PD-MCI groups. Serum UCH-L1 levels were positively correlated with MMSE scores, MoCA scores, and its subitems in PD patients (P < 0.001), and plasma NfL levels were negatively correlated with MMSE scores, MoCA scores, and its items (P < 0.01) (except for "abstract").Decreased UCH-L1 levels and elevated NfL levels in the blood are associated with cognitive dysfunction in PD; thus, these proteins are potential biomarkers for the diagnosis of cognitive dysfunction in PD patients.