Differential role of CSF alpha-synuclein species, tau, and Aβ42 in Parkinson's Disease

Abstract

There is a great interest in developing cerebrospinal fluid (CSF) biomarkers for diagnosis and prognosis of Parkinson's disease (PD). CSF alpha synuclein (α-syn) species, namely total and oligomeric α-syn (t-α-syn and o-α-syn), have shown to be of help for PD diagnosis. Preliminary evidences show that the combination of CSF t-α-syn and classical Alzheimer's disease (AD) biomarkers—β-amyloid 1–42 (Aβ42), total tau (t-tau), phosphorylated tau (p-tau)—differentiate PD patients from controls, and that reduced levels of Aβ42 represent a predictive factor for development of cognitive deterioration in PD. In this prospective study carried out in 44 PD patients and 25 neurological controls we wanted to verify whether the combination of CSF α-synuclein species—t-α-syn and o-α-syn—and classical AD biomarkers may help in differentiating PD from neurological controls, and if these biomarkers may predict cognitive decline. The median of follow-up duration was 3 years (range: 2–6 years). Mini Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were used for monitoring cognitive changes along time, being administered once a year. Oligo/total α-syn ratio (o/t-α-syn ratio) confirmed its diagnostic value, significantly contributing to the discrimination of PD from neurological controls. A greater diagnostic accuracy was reached when combining o/t-α-syn and Aβ42/tau ratios (Sens = 0.70, Spec = 0.84, AUC = 0.82; PPV = 0.89, NPV = 0.62, LR+ = 4.40, DOR = 12.52). Low CSF Aβ42 level was associated with a higher rate of MMSE and MoCA decline, confirming its role as independent predictive factor for cognitive decline in PD. None of the other biomarkers assessed (t-tau, p-tau, t-α-syn and o-α-syn) showed to have prognostic value. We conclude that combination of CSF o/t-α-syn and Aβ42/tau ratios improve the diagnostic accuracy of PD. PD patients showing low CSF Aβ42 levels at baseline are more prone to develop cognitive decline.

P1‐205: Prediction of Conversion of Mild Cognitive Impairment to Dementia with Neuronally Derived Blood Exosome Protein Profile

“…One study reported that a low Ab1-42/P-tau ratio in CSF was the best predictor of cognitive decline and conversion to AD in MCI patients [5]. In contrast, we find that a high expression of P-tau and Ab1-42 in plasma NDEs, that reflect CNS tissue levels of these biomarkers, was the best predictor of the conversion from MCI to AD.…”

“…In current clinical practice, the combination of P-tau and Ab1-42 in CSF has provided the greatest predictive accuracy for the conversion of MCI to dementia [4][5][6][7]. One study reported that a low Ab1-42/P-tau ratio in CSF was the best predictor of cognitive decline and conversion to AD in MCI patients [5].…”

New Frontiers in Alzheimer's Disease Diagnosis

“…A recent study also showed that decreased Aβ42 and increased tau levels are able to discriminate LBD from PD patients in spite of both being synucleopathies [134]. In the same line of evidences, combination of α-synuclein levels and Aβ42/tau ratios improves the diagnostic accuracy of PD [135].…”

Subtype Specific CSF Biomarkers in Sporadic Creutzfeldt-Jakob Disease

“…However, the CSF biomarkers of sCJD and dementia with Lew body sometime concomitant an overlap, with reduced levels of amyloid beta 42 and induced levels of tau [60,[63][64][65]. Therefore, supplementation of alpha synuclein levels may be helpful for the perspective of differential diagnostics.…”