Age-related hippocampal connectivity alterations in HCP-Aging dataset

Motivation: While the hippocampus plays a key role in normal cognition and Alzheimer's disease, studies examining diffusion characteristics along the tracts connecting the hippocampus with other brain regions in aging populations remain limited. Goal(s): To map the major hippocampal connectivity pathways and investigate their age-related diffusion characteristics changes. Approach: Leveraging high-resolution diffusion MRI from HCP-Aging, we mapped whole-brain white matter connections and isolated hippocampal sub-tracts, and analyzed hippocampal connections and diffusion parameters in relation to age. Results: With aging, the density and streamline count of the global hippocampal connectivity were reduced, suggesting the degeneration of major hippocampal pathways. Impact: These findings support the observed hippocampal volume changes in age-related cognitive decline, and provide insights into the 'hippocampal disconnection' theory, highlighting the importance of the integrity of hippocampal-centered white matter network associated with aging.