Subcortical deformation is uniquely related to cortical thickness among FTLD mutation carriers

Abstract

AbstractBackgroundFrontotemporal lobar degeneration (FTLD) due to familial mutations results in heterogenous clinical phenotypes for which there are no specific biomarkers. Here, we test whether subcortical deformation differs in FTLD genetic mutation carriers, and if deformation was uniquely related to cortical thickness.Method317 participants from ALLFTD with familial FTLD (C9orf72 (n = 139), GRN (n = 77), and MAPT (n = 101)) and 27 controls without mutations (NCC) were evaluated. MRI data underwent FreeSurfer processing to estimate cortical thickness (CT). High‐dimensional, large‐deformation diffeomorphic metric mapping was used to model surfaces of the caudate and putamen. Regression analyses investigated the effect of mutation on CT and subcortical surface deformation, after controlling for age, sex, and education. Finally, linear models were constructed in each mutation group to explore the association between areas of significant surface deformity and CT, corrected for age and multiple comparisons.ResultFigure 1 shows significant (corrected p<.05) T‐scores where mutation carrier groups differ in CT from NCC (red = greater atrophy in mutation). Figure 2 shows greater outward local deformation in the caudate body among C9 and MAPT compared to NCC. Significant relationships between deformation and CT (corrected p<.05) were observed in bilateral temporoparietal, frontal and cingulate cortex in both C9 and MAPT carriers. C9 and MAPT mutation carriers have greater outward deformation in postero‐lateral putamen. Deformation was associated with CT in C9 within the left temporal and prefrontal lobes, and in the right temporoparietal, occipital and cingulate cortices for MAPT (Figure 3). No significant deformation was observed in GRN compared to NCC.ConclusionFamilial FTLD mutations are associated with subtle subcortical shape variations that show unique relationships to cortical atrophy.