NEFL and Alzheimer disease: Moreover, the significant increase in GFAP and NfL levels observed in FTD and AD patients compared to controls confirms the presence of neuronal damage and corroborates previous data regarding the capability of these biomarkers in identifying FTD, AD, and related dementia compared to the cognitively healthy elderly, as well as in assessing FTD and AD severity and prognosis [39,40,55,56].