Plasma levels of soluble tumor necrosis factor receptors are associated with cognitive performance in Parkinson's disease

Abstract

Inflammatory mechanisms have been implicated in a series of neuropsychiatric conditions, including behavioral disturbances, cognitive dysfunction, and affective disorders. Accumulating evidence also strongly suggests their involvement in the pathophysiology of Parkinson's disease (PD). This study aimed to evaluate plasma levels of inflammatory biomarkers, and their association with cognitive performance and other non-motor symptoms of PD. PD patients and control individuals were subjected to various psychometric tests, including the Mini-Mental State Examination (MMSE), Frontal Assessment Battery (FAB), and Beck's Depression Inventory (BDI). Biomarker plasma levels were measured by enzyme-linked immunosorbent assay (ELISA). PD patients exhibited worse performance on MMSE and the programming task of FAB, and presented higher soluble tumor necrosis factor receptor (sTNFR) plasma levels than control individuals. Among PD patients, increased sTNFR1 and sTNFR2 concentrations were associated with poorer cognitive test scores. After multiple linear regression, sTNFR1 and education remained a significant predictor for FAB scores. Our data suggest that PD is associated with a proinflammatory profile, and sTNFRs are putative biomarkers of cognitive performance, with elevated sTNFR1 levels predicting poorer executive functioning in PD patients.