Effects of Age, Sex, and Associative Load on Memory and its Relation to White Matter Microstructure

Poster Session E - Monday, April 15, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

Abbey Page¹, Shruti Prabhakar, Jamilah Zubair, Ilana Bennett; ¹University of California at Riverside

Associative memory is worse with age, in males, and when there are more items to be remembered together (higher associative load). Independent of the age and sex effects, memory for associations between pairs of items has been linked to microstructure of white matter tracts that connect the hippocampus to the frontal cortex (e.g., fornix). However, less is known about relationships between white matter microstructure and memory for higher associative loads. The current study investigated these effects in 17 younger and eight older adults who completed a novel associative memory task where they studied and were subsequently tested on word sets of varying sizes (pairs, triplets, and quadruplets). A high-resolution diffusion-weighted MRI scan was also obtained from which single-tensor measures of tissue microstructure were extracted from standard fronto- and medial-temporal tracts of interest. Behavioral data revealed better associative memory in younger than older adults, males than females, and for pairs than triplets or quadruplets. Diffusion data revealed better integrity (higher fractional anisotropy, lower mean diffusivity) in the fornix and bilateral sagittal stratum in younger than older adults. When controlling for age group and sex, partial correlations further revealed that the extent to which associative memory was modulated by set size (i.e., larger difference in performance to pairs than quadruplets) significantly related to sagittal stratum integrity. These findings highlight a possible role of the sagittal stratum, which connects the brainstem and thalamus to temporo-occipital-parietal white matter, in associative memory, particularly at higher associative loads.

Topic Area: LONG-TERM MEMORY: Development & aging