NEFL and frontotemporal dementia: Serum and plasma NF-L concentrations correlate with their concentrations in the CSF (correlation coefficients of 0.75 to 0.97), and most measurements in the CSF (increased NF-L concentrations in AD, FTD, VaD and in atypical parkinsonian disorders) have been replicated in blood (Zetterberg, 2016).