Poster B92, Sunday, March 26, 8:00 – 10:00 am, Pacific Concourse
Age-related dedifferentiation of anterior and posterior hippocampal structural whole-brain covariance
Kristin Nordin1, Jonas Persson1, Eva Stening1, Agneta Herlitz2, Elna-Marie Larsson1, Hedvig Söderlund1; 1Uppsala University, Uppsala, Sweden, 2Karolinska Institutet, Solna, Sweden
Structural whole-brain covariance, i.e. patterns of gray matter expressing associations among regions, potentially functionally significant, displays alterations in older age. Linked to memory impairments in both normal aging and Alzheimer’s disease, decreases in covariance are interpreted as a sign of network decoupling, and increases as dedifferentiation of functional organization. Additionally, numerous studies report interrelated effects of age on regional hippocampal volume and memory performance, but even though the hippocampus interacts with distributed regions to support memory, little is known about age effects on hippocampal whole-brain structural covariance. Using voxel-based morphometry (VBM) and the multivariate approach partial least squares (PLS), we therefore assessed regional volume and structural covariance of the hippocampus in young, middle-aged and older adults (n=221), and measured spatial and episodic memory. Based on findings of a functional division along the hippocampal longitudinal axis, we specifically assessed age differences in relation to axis. Regional volume differences followed a posterior-to-anterior gradient across age groups, and performance on both memory tasks correlated negatively with age. There were two significant covariance patterns; a main pattern capturing common anterior and posterior whole-brain covariance, and a secondary pattern differentiating the two. While the first pattern was predominantly driven by the middle-aged and older groups, the second pattern was driven by younger and middle-aged women specifically. As this dedifferentiation of anterior and posterior structural covariance with increasing age was paralleled by inferior spatial and episodic memory, it is possible that memory organized along the hippocampal long-axis benefits from differentiation in structural covariance.
Topic Area: LONG-TERM MEMORY: Development & aging