Cardiovascular Risk Indices Differentially Linked to Hippocampal Subfield Volumes: A Comparison Between Younger and Older Adults

The hippocampus, a key neural structure supporting episodic memory, comprises distinct subfields including the dentate gyrus (DG), Cornu Ammonis (CA1-3), and subiculum. Hippocampal subfields typically show age-related volumetric decline across adulthood, but the regional aging may be differentially vulnerable to cardiovascular risk factors. Here, we examined the association between hippocampal subfield volumes and cardiovascular risk indices-hypertension, blood pressure variation (BPV), body mass index (BMI), and waist-to-hip ratio-in groups of younger (n = 37, ages 18-29 years) and older adults (n = 22, ages 60-79 years). The findings revealed a specific link between cardiovascular health and hippocampal subfield volumes, with the subiculum showing greater sensitivity. Among younger adults, hypertension predicted smaller subiculum, while higher BMI correlated with larger CA1-2 volumes. For older adults, higher BPV predicted smaller subiculum volume, independent of hypertension that correlated with larger regional volume. Age moderated the relation between all indices and subiculum volume except waist-to-hip ratio. These findings highlight age-dependent, subfield-specific risk factors for hippocampal aging and underscore the potential for identifying sensitive periods for both risk and protection against late-life cognitive decline.