Cerebrospinal fluid and plasma clusterin levels in Parkinson's disease

Clusterin is a multifunctional chaperone protein that has repeatedly been linked to Alzheimer's disease (AD) pathogenesis and, more recently, also to Parkinson's disease (PD) by both genetic and proteomic analyses. Although clusterin is detectable in cerebrospinal fluid (CSF) and plasma, studies comparing clusterin levels in PD patients and controls have been scarce and yielded conflicting data. The aim of the present study was to determine whether CSF and/or plasma clusterin levels differ between PD patients and controls and are related to disease severity. We measured CSF and plasma clusterin levels in a group of 52 PD patients and in 50 age-matched neurologically healthy controls and found that clusterin levels in CSF and plasma were not different between the two groups. Furthermore, clusterin levels in CSF and plasma were not associated with disease duration, stage or severity. CSF clusterin levels did, however, correlate with CSF levels of total tau, phospho-tau and amyloid-β-42. We elaborate on the identified correlations between levels of clusterin and AD related proteins and on possible explanations for the discrepant findings in clusterin studies in PD so far.