TARDBP and frontotemporal dementia: Validation studies have demonstrated that ICVF correlates with histologically quantified axonal density measures.15 The unique ICVF pattern seen in nfvPPA may be linked to a higher frequency of tau proteinopathy compared with other FTD variants.40,41 Indeed, previous studies suggest more severe WM pathology in FTD-tau than FTD-TDP43.38 Further investigations with pathological validation are needed to confirm this hypothesis.