Deviations in Hippocampal Subregion Associated With Cognitive and Physical Frailty in Older Adults With Cognitive Frailty

Background: The hippocampus is a complex, heterogeneous structure that is composed of widely different and interacting subregions. Atrophy of these subregions has been implicated in a variety of neurodegenerative diseases. Cognitive frailty is a kind of neurodegenerative disease with unclear neuropathological changes. The aim of this study was to explore the changes in hippocampal subregions in older adults with cognitive frailty and the relationship between subregions and cognitive decline as well as physical frailty. Methods: Twenty-six older adults with cognitive frailty and 26 matched healthy controls were included in this study. Cognitive function was evaluated by the Montreal Cognitive Assessment (MoCA) scale (Fuzhou version) and Wechsler's Memory Scale, while physical frailty was tested with the Chinese version of the Edmonton Frailty Scale (EFS) and grip strength. The volume of the hippocampal subregions was measured with structural brain magnetic resonance imaging. Partial correlation analysis was carried out between the volumes of hippocampal subregions and MoCA scores, Wechsler’s Memory Quotient and physical frailty indexes. Results: A significant volume decrease was found in six hippocampal subregions, including the bilateral presubiculum, the left parasubiculum, molecular layer of the HP, and HATA, and the right CA1 area, in older adults with cognitive frailty ( P <0.05/12), while the proportion of brain parenchyma and total number of white matter fibers were lower than those in the healthy controls ( P <0.05). Positive correlations were found between Wechsler’s Memory Quotient and the size of the left molecular layer of the HP and HATA and the right presubiculum ( P <0.05). The sizes of the left presubiculum, molecular of the layer HP, and HATA and right CA1 and presubiculum were found to be positively correlated with MoCA score ( P <0.05). The sizes of the left parasubiculum, molecular layer of the HP and HATA were found to be negatively correlated with the physical frailty index ( P <0.05). Conclusion: Significant volume decrease occurs in hippocampal subregions of older adults with cognitive frailty, and these changes are correlated with cognitive decline and physical frailty. Therefore, the atrophy of hippocampal subregions could participate in the pathological progression of cognitive frailty.