B-72: Examining Physical Activity as a Moderator of White Matter Hyperintensity Volume and Specific Cognitive Domain Performance

Abstract

Objective: Research is mixed regarding the role of physical activity (PA) on the relationship between white matter hyperintensity volume (WMHV) and specific cognitive domains. We examined the relationships between WMHV and processing speed and executive functioning, and whether PA moderated these relationships. Method/Data Selection: Participants were 1542 clinically normal or mildly impaired adults (Clinical Dementia Rating Scale ≤ 0.5) from the Health and Aging Brain Study–Health Disparities cohort. Hierarchical linear regression models examined whether log-transformed WMHV from MRI and self-reported frequency and intensity of PA (Rapid Assessment of Physical Activity questionnaire) were associated with composite scores for processing speed (Trail Making Test Part A; Digit Symbol Substitution) and executive functioning (Trail Making Test Part B; FAS fluency; Digit Span Forward and Backward). Models adjusted for age (M=66.13, SD=8.58), education (M=14.91, SD=2.85), sex (61% female), and number of vascular conditions (M=1.61, SD=0.95). A WMHV and PA interaction term was subsequently included. Results/Data Synthesis: Greater WMHV was associated with worse processing speed (ps<.02) and executive functioning (ps<.001). Greater PA was associated with better processing speed (ps<.05), but not executive functioning. Adding WMHV and PA explained a small, but significant, proportion of additional variance in both models (ΔR2s=.007, ps<.01). The interaction between WMHV and PA was not significant for either domain. Conclusions: Consistent with prior research, greater WMHV was associated with worse performances in processing speed and executive functioning; however, PA did not moderate these relationships for either domain in this sample. Future exploration of additional mechanisms for modifying the relationship between WMHV and cognition is recommended.