NEFL and Cognitive impairment: However, given the negative association with disease duration in our study, there may be a differential profile of CSF sTREM2 according to disease stage in FTD, as has been identified in the continuum from mild cognitive impairment to AD [24, 25], or according to disease intensity, as has been identified for serum and CSF neurofilament light chain levels in FTD [30, 31], which would be clinically useful.