Combined measurement of plasma cystatin C and low-density lipoprotein cholesterol: A valuable tool for evaluating progressive supranuclear palsy

Introduction: Progressive supranuclear palsy (PSP) was previously thought as a cause of atypical Parkinsonism. Although Cystatin C (Cys C) and low-density cholesterol lipoprotein-C (LDL-C) are known to play critical roles in Parkinsonism, it is unknown whether they can be used as markers to distinguish PSP patients from healthy subjects and to determine disease severity. Methods: We conducted a cross-sectional study to determine plasma Cys C/HDL/LDL-C levels of 40 patients with PSP and 40 healthy age-matched controls. An extended battery of motor and neuropsychological tests, including the PSP-Rating Scale (PSPRS), the Non-Motor Symptoms Scale (NMSS), Geriatric Depression Scale (GDS) and Mini-Mental State Examination (MMSE), was used to evaluate the disease severity. Receiver operating characteristic (ROC) curves were adopted to assess the prognostic accuracy of Cys C/LDL-C levels in distinguishing PSP from healthy subjects. Results: Patients with PSP exhibited significantly higher plasma levels of Cys C and lower LDL-C. The levels of plasma Cys C were positively and inversely correlated with the PSPRS/NMSS and MMSE scores, respectively. The LDL-C/HDL-C ratio was positively associated with PSPRS/NMSS and GDS scores. The ROC curve for the combination of Cys C and LDL-C yielded a better accuracy for distinguishing PSP from healthy subjects than the separate curves for each parameter. Conclusions: Plasma Cys C and LDL-C may be valuable screening tools for differentiating PSP from healthy subjects; while they could be useful for the PSP intensifies and severity evaluation. A better understanding of Cys C and LDL-C may yield insights into the pathogenesis of PSP.