Moderating effects of limbic white matter on verbal memory in older adults with multiple sclerosis.

Objective: Literature concerning the structural brain correlates of verbal memory in aging with multiple sclerosis (MS) is scarce. This study addressed this gap by examining the impact of white matter microstructure and macrostructure on verbal memory in older adults with and without MS.

Method: Participants were 64 older adults with MS (OAMS; age M [SD] = 64.19 [3.82]) and 72 controls (age M [SD] = 69.78 [6.99]). Verbal memory was measured using the Hopkins Verbal Learning Test-Revised (HVLT-R), and white matter fractional anisotropy and lesion volume were extracted from diffusion tensor and fluid-attenuated inversion-recovery magnetic resonance imaging. Statistical models examined whether white matter measures moderated the association between the presence of MS and HVLT-R performance.

Results: Adjusted moderation models revealed that OAMS showed lower HVLT-R total immediate recall compared to controls in the presence of higher lesion volume in the bilateral fornices, left uncinate fasciculus, and right ventral cingulum, and lower HVLT-R delayed recall in the presence of lower fractional anisotropy in the right ventral cingulum and higher lesion volume in the left uncinate fasciculus and right ventral cingulum, with small effect sizes (interaction term ΔR²s = .03-.06, ps < .05).

Conclusions: Recall was lower in OAMS when limbic tract white matter had lower integrity and higher lesion load. Findings suggest that the influence of MS on verbal memory in older adults is related, in part, to underlying white matter disruptions in tracts implicated in memory. While the sample was generally representative of the U.S. MS population (majority White women), generalizability is limited and warrants further research. (PsycInfo Database Record (c) 2025 APA, all rights reserved).