Amyloid (a), tau (t) and voxel‐based morphometry (n) correlates of visual memory performance

Abstract

AbstractBackgroundThe Aggie Figures Learning Test (AFLT) is a memory test that was designed to be a visual analogue of the Rey Auditory Verbal Learning Test (RAVLT). Previous studies have found associations between tau and amyloid PET and brain volume and RAVLT scores. However, to date, no study has explored the associations between these markers and AFLT scores. We aimed at exploring such associations.MethodsStructural MRI, amyloid PET ([18F]‐NAV4694) and tau PET ([18F]‐MK6240) were acquired for 161 individuals. We conducted analyses on two sub‐samples. Demographic data is shown on Tables 1 and 2. MRI were segmented into probabilistic grey (GM) and white (WM) maps, non‐linearly registered to the ADNI template using Dartel and smoothed with an 8mm FWHM gaussian kernel. Voxel‐wise linear regression models were applied, using VoxelStats, with AFLT sub‐scores as dependent variables and either tau and amyloid binding or Voxel‐Based Morphometry as predictors. We corrected for sex, Apoe genotype, age and years of education.ResultsWe found negative associations between tau binding and AFLT total (trials 1‐5) and AFLT delayed recall (DR) scores in the MTL and temporo‐occipital cortices, as well as in some of their WM tracts. These associations were stronger for the total scores and, in both cases, in the right hemisphere. For the amyloid biomarker, associations with AFLT total and AFLT DR scores were negative in right ventromedial PFC, right posterior thalamus and basal ganglia. In this case, strongest associations are reported between amyloid burden and AFLT DR scores. Finally, we found positive associations between AFLT total and DR scores and VBM in the fusiform gyrus bilaterally.ConclusionsResults resemble previously reported findings on associations between RAVLT and tau, amyloid and brain volume estimates. Our findings are also in line with initial reporting of patients with right hemisphere damage having difficulties with AFLT tasks (Madjan, et al. 1996). In addition, relationships with tau tend to be more posterior, while relationships with amyloid were shown to be more anterior. Further analyses based on diagnostic categories are needed to explore how these associations change with pathology.