Brain activation patterns associated with working memory in relapsing-remitting MS

Background: Patients with multiple sclerosis (MS) show changes in brain activation patterns during visual and motor tasks that include decreases in the typical local network for a function and increases in other brain regions. Objective: To determine whether brain activation patterns associated with working memory are affected by MS. Methods: Activation of working memory circuitry was examined using an fMRI n-back task in adults with mild relapsing-remitting MS (RRMS; n=10) and demographically matched healthy controls (n=10). Results: Group differences in brain activation emerged during both low- and high-demand conditions (p<0.001). Overall, patients showed less activation than controls in core prefrontal and parietal regions of working memory circuitry, and greater activation in other regions within and beyond typical working memory circuitry, including bilateral medial frontal, cingulate, parietal, bilateral middle temporal, and occipital regions. Conclusions: Relative to controls, patients with mild RRMS showed shifts in brain activation patterns within and beyond typical components of working memory circuitry.