Poster C38, Sunday, March 26, 5:00 – 7:00 pm, Pacific Concourse
Moderating Effect of White Matter Integrity on Task-Related Brain Activation
Melanie Lucas1, Helena Blumen2, Meltum Izzetoglu3, Roee Holtzer1,2; 1Ferkauf Graduate School of Psychology, Yeshiva University, Bronx, NY, 2Albert Einstein School of Medicine, Yeshiva University, Bronx, NY, 3School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA
As part of normal aging white matter integrity (WMI) decreases and there is a tendency for cortical overactivation with increasing executive demands. There is a paucity of research examining factors that may influence cortical overactivation. This study used diffusion-weighted imaging (DWI) and functional near infrared spectroscopy (fNIRS) to determine whether WMI moderated the change prefrontal cortex (PFC) oxygenation levels assessed under single and dual-task walking conditions. Specifically, we hypothesized that lower (i.e., worse) WMI would be associated with a greater increase in PFC oxygenation levels from single to dual-task walking conditions. Methods: Participants (n=62) were community-residing older adults. fNIRS was used to measure changes in oxygenated hemoglobin (HbO2) during walking. An overall Fractional Anisotropy (FA) values derived from DWI were used to quantify WMI. Linear mixed effects models were used to assess the effect of dual-tasking on gait velocity and PFC HbO2 Levels. Covariates included age, gender, education and a disease comorbidity index. Results: As expected, gait velocity declined (beta=1.86 ; p<.001) but PFC HbO2 levels increased (beta=1.03; p=<.001) from single- to dual-task walking. However, WMI moderated the effect of dual-tasking on PFC oxygenation. Specifically, lower WMI was associated with a greater increase in PFC HbO2 levels from single to dual-task walking (beta=.58; p<.001). Conclusion: We propose WMI as a mechanism underlying inefficient brain response to cognitive demands of locomotion.
Topic Area: EXECUTIVE PROCESSES: Development & aging