Elevated Cystatin C Levels Are Associated with Cognitive Impairment and Progression of Parkinson Disease.

Objective:We investigated the relationship between serum cystatin C (CysC) levels and cognitive dysfunction and disease progression in patients with Parkinson disease.Background:Previous studies have reported altered CysC levels in neurodegenerative disorders, but only a few studies have explored the role of CysC and its relationship to cognitive dysfunction in Parkinson disease.Methods:We measured serum levels of CysC, creatinine, urea, and uric acid in 142 patients with Parkinson disease and 146 healthy controls. We assessed disease progression using the Hoehn and Yahr scale, and cognitive function using the Montreal Cognitive Assessment (Beijing version).Results:The patients with Parkinson disease had significantly higher CysC levels than the controls (P<0.001). CysC level correlated significantly with age (r=0.494, P<0.001), sex (r=0.150, P=0.011), and serum creatinine level (r=0.377, P<0.001), but not with levels of urea or uric acid (P>0.05). CysC level was a significant independent predictor of Parkinson disease (odds ratio=23.143, 95% confidence interval: 5.485-97.648, P<0.001) in multivariate logistic regression analysis. In the Parkinson disease group, a higher CysC level was associated with a more advanced Hoehn and Yahr stage (r=0.098, P<0.05) and a lower Montreal Cognitive Assessment score (r=-0.381, P=0.003).Conclusions:Serum CysC levels can predict disease severity and cognitive dysfunction in patients with Parkinson disease. The exact role of CysC remains to be determined.