Clinical subtypes of frontotemporal dementia show different patterns of cortical atrophy

Abstract

AbstractBackgroundFrontotemporal dementia (FTD) is a progressive neurodegenerative disorder associated with atrophy of the frontal and/or anterior temporal lobes, it is highly heterogeneous and represents about 5% of all cases of dementia and it is one of the most common causes of early‐onset dementia (Onyike and Diehl‐Schmid, 2013). FTD syndromes can be divided into three major groups: the behavioral variant (bvFTD) characterised by prominent early behavioral and personality changes, and the two language variants: the semantic variant (svFTD) and the non‐fluent primary progressive aphasia (pnfaFTD).MethodIn our study we used MRI scans from a frontotemporal lobar degeneration neuroimaging initiative (FTLDNI) database: 133 age and sex matched controls, 70 bvFTD, 36 svFTD and 30 pnfaFTD. Each scan was pre‐processed (Intensity normalization, N3, linear registration, brain masking); tissue classification was performed using BISON (Dadar 2020). All scans were then processed using FALCON (Fonov 2020) to extract its cortical surface anc calculate thickness. Statistical analysis was performed on vertex level.ResultFigure 1 shows relative cortical difference between groups relative to controls, Figure 2 shows areas of significant differences (FDR 1%): the decrease of cortical thickness in the bvFTD group was located in frontal lobes, bilaterally as well as the temporal poles (specially in medial frontal and dorsolateral prefrontal areas). In svFTD, however, cortical thinning is limited to the anterior and lateral temporal lobe, predominantly on the left side. Finally, pnfaFTD shows left sided cortical thinning in prefrontal and Broca’s areas.ConclusionThe identification of predicted patterns of atrophy in each FTD subtype supports the validity of FALCON as an accurate tool to measure cortical changes in neurodegenerative disease. FALCON could be a useful tool for the development of the biomarkers associated with disease and improve understanding of disease progression.