NEFL and dementia: Although the studies discussed above used either serum/plasma NfL or CSF NfL, we found a moderate correlation between plasma and CSF NfL (Spearman’s rho = 0.568, p < 0.001) in 79 elderly participants without dementia (median age 76.5 [IQR 71.7–80.7]) (Mielke et al., 2019).