Alpha-synuclein in the Cerebrospinal Fluid Differentiates Synucleinopathies (Parkinson Disease, Dementia With Lewy Bodies, Multiple System Atrophy) From Alzheimer Disease

Background: We examined the utility of quantification of alpha-synuclein (SNCA) in the cerebrospinal fluid (CSF) to differentiate patients with Alzheimer disease (AD), dementia with Lewy bodies (DLB), Parkinson disease (PD), and multiple system atrophy (MSA). Methods: Thirty-seven patients were divided into 4 age-matched and sex-matched clinical groups: AD (n = 9), DLB (n = 6), PD (n = 11), and MSA (n = 11). Eleven subjects served as neurological disease controls. The total of 48 subjects included 27 men and 21 women, aged 66.5 +/- 11.4 years. We performed a solid-phase sandwich enzyme-linked immunosorbent assay, which enables the sensitive quantification of CSF SNCA. Results: In comparison with controls, CSF SNCA levels in AD were significantly higher (P < 0.05). CSF SNCA levels in PD (P < 0.001), DLB (P < 0.01), and MSA (P < 0.05) were all significantly lower than those in AD. However, CSF SNCA levels did not differ significantly among the 3 synucleinopathies. Conclusions: The results of the present study suggest that quantification of CSF SNCA helps in the differentiation of synucleinopathies (PD, DLB, and MSA) from AD. However, CSF SNCA levels did not differ significantly among the 3 synucleinopathies.