Memory impairment in Alzheimer’s disease is associated with Dentate Gyrus atrophy: A pilot study using the Uniform Data Set Neuropsychological Battery and 7 Tesla MRI

Abstract

AbstractBackgroundThe neuropsychological battery of the Uniform Data Set (UDSNB3.0) (Weintraub et al., 2009) assesses cognition. The neuroanatomical correlates of the UDSNB3.0 have not yet been investigated. 7T MRI was used to investigate correlations between hippocampal subfield volumes and the UDSNB3.0 for Alzheimer’s disease (AD) and age‐matched healthy control (HC).Method28 (15 AD, 13 HC) participants (61% female; aged 42‐79) were recruited. A Phillips Achieva 7T scanner used a Nova Medical (Wilmington MA, USA) single‐channel transmit, 32 channel receive (1Tx32Rx) head‐coil. PSIR images (TE/TR = 119/59001ms, FA = 90o, 0.38×0.39×1.50 mm3 resolution) were segmented into Cornu Ammonis (CA = CA1+CA2+CA3), Subiculum (SUB), Dentate Gyrus (DG), and Entorhinal Cortex (ERC) (Figure 1). The UDSNB3.0, administered by trained Assistant Psychologists, included the MoCA and a variety of cognitive tests assessing memory (immediate/delayed recall, un‐cued/cued recall, and recognition), attention, language and visuospatial abilities.ResultIn the whole analysed sample (n = 28), there were strong positive correlations between UDS3.0 memory test scores and hippocampal subfield volumes (Figure 2). There were significant reductions in the volume of each hippocampal subfield in AD, compared with controls (p<0.05). No significant decrease in the whole brain volume was noted between the two groups (p>0.05), indicating that hippocampal volume loss was not part of whole brain atrophy. One‐way ANOVA’s demonstrated significant differences between HC and AD test scores (p<0.05), thus HC and AD participants were analysed separately. In AD participants, whole hippocampal volume correlated with MoCA memory category cue scores (R2 = 0.54, p<0.05) but only significantly in the DG of the hippocampal subfields (R2 = 0.52, p<0.05) (Figure 3), supporting Novellino et al.’s (2018) previous finding of associations between the DG volume and cued recall. No such significant correlations were observed in HC participants.ConclusionThe results of this study confirm that hippocampal atrophy in AD is associated with cognitive decline. Additionally, our results suggest that 7T MRI may be able to detect subtle in vivo DG atrophy in AD that is related to cued memory. The 7T scans appear to reveal DG changes in AD that to date have been confirmed in neuropathological studies only.Funding: The Medical Research Council, UK has funded AAH (MR/T005580/1).