Dissociable age and memory relationships with hippocampal subfield volumes in vivo:Data from the Irish Longitudinal Study on Ageing (TILDA)

Abstract

The heterogeneous specialisation of hippocampal subfields across memory functions has been widely shown in animal models. Yet, few in vivo studies in humans have explored correspondence between hippocampal subfield anatomy and memory performance in ageing. Here, we used a well-validated automated MR segmentation protocol to measure hippocampal subfield volumes in 436 non-demented adults aged 50+. We explored relationships between hippocampal subfield volume and verbal episodic memory, as indexed by word list recall at immediate presentation and following delay. In separate multilevel models for each task, we tested linearity and non-linearity of associations between recall performance and subfield volume. Fully-adjusted models revealed that immediate and delayed recall were both associated with cubic fits with respect to volume of subfields CA1, CA2/3, CA4, molecular layer, and granule cell layer of dentate gyrus; moreover, these effects were partly dissociable from quadratic age trends, observed for subiculum, molecular layer, hippocampal tail, and CA1. Furthermore, analyses of semantic fluency data revealed little evidence of robust associations with hippocampal subfield volumes. Our results show that specific hippocampal subfields manifest associations with memory encoding and retrieval performance in non-demented older adults; these effects are partly dissociable from age-related atrophy, and from retrieval of well-consolidated semantic categories.

Hemodynamic and structural brain measures in high and low sedentary older adults

“…Hippocampal subfield volumes were analysed with a linear mixed model with subfields nested in hemispheres, nested in participants. 11 Interactions between the categorical variable subfield and SB were used to assess the effect of SB on each subfield volume.…”

“…Initially participants aged 65þ were prioritised during recruitment, later participants aged 50-64 years were targeted. 9,11 This resulted in the inclusion of 578 participants. Sample characteristics and response rates of the different waves have been reported previously.…”

“…In short, this procedure uses a probabilistic atlas based on ex-vivo manual segmentations and in-vivo T1 scans, to segment new T1 images based on probabilities. 11 Segmentations were checked by trained operators. 11 All volumetric analyses were corrected for estimated total intracranial volume (eTIV), calculated based on the method of Buckner et al 20 Fluid attenuated inversion recovery (FLAIR) images were acquired using a 2D turbo spin-echo sequence (FOV (mm): 230x230; TR: 11000 ms; TE: 125 ms; TI: 2800 ms; flip angle: 90 ; number of slices: 30; slice thickness: 4 mm; slice gap: 1 mm; voxel size (mm): 0.45x0.45).…”

“…11 Segmentations were checked by trained operators. 11 All volumetric analyses were corrected for estimated total intracranial volume (eTIV), calculated based on the method of Buckner et al 20 Fluid attenuated inversion recovery (FLAIR) images were acquired using a 2D turbo spin-echo sequence (FOV (mm): 230x230; TR: 11000 ms; TE: 125 ms; TI: 2800 ms; flip angle: 90 ; number of slices: 30; slice thickness: 4 mm; slice gap: 1 mm; voxel size (mm): 0.45x0.45). 21 One trained radiologist scored all images with the Scheltens scale to grade WMHs, with a part (n ¼ 100) independently scored by two radiologist (strong coefficient of agreement, 0.82).…”

The human hippocampus and its subfield volume across age, sex and APOE e4 status

“…Differential effects of age, sex and APOE e status on annualised sub eld volume change Prior studies report highly variable results regarding which sub elds are most vulnerable to ageing (Frisoni et al 2008;Carey et al 2019;Wisse et al 2014). CA1 is fairly consistent in its association with ageing, but the subiculum has been shown to be both relatively spared in ageing, but implicated in AD-related atrophy (Wisse et al 2014; Daugherty et al 2016), and to be the sub eld most affected by ageing (Malykhin et al 2017; Kurth, Cherbuin, and Luders 2017).…”