The negative correlation between CSF NfL and brain and cortical volumes is in line with findings in a cohort of mainly sporadic FTD patients in which a negative correlation with gray and white matter volume was found.10 This supports the hypothesis that NfL levels reflect the extent of neurodegeneration.16 So far, the positive correlation between CSF NfL and occipital volume in our patients is difficult to explain. Here, NEFL is linked to frontotemporal dementia.