CSF α-synuclein concentrations do not fluctuate over hours and are not correlated to amyloid β in humans.

Reports on the value of cerebrospinal fluid (CSF) α-synuclein as a biomarker for dementia with Lewy bodies and Parkinson disease are contradicting. This may be explained by fluctuating CSF α-synuclein concentrations over time. Such fluctuations have been suggested for CSF amyloid β concentrations. Furthermore, a physiological relationship between α-synuclein and amyloid β has been suggested based on in vitro research. We performed repeated CSF sampling in healthy elderly and AD patients and showed that sinusoidal fluctuations in CSF α-synuclein concentrations were not present. Furthermore, we did not find evidence for an interaction between amyloid β and α-synuclein concentrations in CSF.