Associations between hippocampal subfield volume and cognitive performance

Abstract

AbstractBackgroundIt is well demonstrated that hippocampal atrophy is associated with cognitive impairment. Existing studies have associated smaller hippocampal volumes with dementia, and hippocampal volume reduction has been established as a biomarker for the conversion of mild cognitive impairment to Alzheimer’s Disease. Although some studies have examined correlations between hippocampal subfield volumes and cognitive domains such as memory, further research is needed to clarify the associations between the volume of each subfield and the various cognitive domains. So far a few studies have been conducted among Asian populations. A more specific understanding of these relationships is crucial given the functional and histological differences in the subfields and their distinct patterns of atrophy, which imply that the hippocampal subfields may affect cognition differentially. This study aimed to investigate the associations between the volumes of 12 hippocampal subfields on cognitive performance in a Singaporean sample.Method448 patients at a memory clinic in Singapore (97 with no cognitive impairment, 177 with CIND, and 174 with dementia) underwent magnetic resonance imaging (MRI) and a neuropsychological assessment. MRI was processed through free surfer (v.6.1) to extract volumes of 12 hippocampal subfields—the tail, subiculum, presubiculum, parasubiculum, CA1, CA3, CA4, fimbria, fissure, molecular layer, the molecular and granule cell layers of the of the dentate gyrus (GCMLDG), and the hippocampus‐amygdala transition area (HATA). Cognition was assessed using NINDS–Canadian Stroke Network harmonization neuropsychological battery.ResultGlobal cognition was associated with the subiculum, presubiculum, CA1, CA3, CA4, molecular layer, and GCMLDG (all p‐values < .0005). Except for the fissure, all hippocampal subfields were associated with visuospatial skills (all p‐values < .05) and memory (all p‐values < .035). The fimbria was associated with the most cognitive domains, including executive dysfunction (p = .011), language (p = .006), visuomotor function (p = .003), visuospatial skills (p < .001), and memory (p < .001).ConclusionThe current study builds on existing research on the associations between hippocampal subfield volumes and cognitive dysfunction. Longitudinal studies are required to investigate the volumetric reduction of hippocampal subfields as a biomarker of cognitive decline.