Aerobic Exercise Training and Depressive Symptoms in People With Multiple Sclerosis: Brief Report on Default-Mode Network Resting-State Functional Connectivity.

Background: We sought to examine a potential neural mechanism of reduced depressive symptoms in response to aerobic treadmill walking exercise training in people with multiple sclerosis (MS). This includes a secondary analysis of depressive symptom and MRI data from an original randomized controlled trial (RCT) on exercise effects on learning and memory impairment in people with MS.

Methods: Ten fully ambulatory people with MS were randomly assigned into either a 12-week aerobic treadmill walking condition or active control condition (ie, stretching and range-of-motion activities). All participants completed the Hospital Anxiety and Depression Scale for measurement of depressive symptoms as well as a resting-state functional MRI (fMRI) before and after the 12-week study period.

Results: There were no between-condition differences in depressive symptoms at baseline. Participants who were randomly assigned to the intervention condition demonstrated reductions in depressive symptoms compared with minimal changes for those who underwent the control condition. This corresponded with significant changes in resting-state functional connectivity within the default-mode network (DMN).

Conclusions: The overall pattern of results suggests that resting-state functional connectivity within the DMN may represent a potential neural mechanism underlying the beneficial effects of exercise on depressive symptoms in people with MS. Such results warrant future consideration in the design and conduct of future RCTs that aim to treat MS-related depression with aerobic exercise training in people with MS who have been prescreened for clinical depression.