Physical activity and depression in MS: The mediating role of behavioral activation

Background: Depression is a common comorbid condition among individuals with multiple sclerosis (MS) and is associated with greater overall disease burden and lower quality of life. Numerous clinical trials have supported physical activity interventions versus education, usual care, and attention control conditions for improving depressive symptoms in individuals with MS. However, little is known about the psychological mechanisms that may underlie physical activity-related improvements in depression. Behavioral activation posits that depression may stem from a reduction or loss of personally meaningful and rewarding activity. The process of behavioral activation involves re-engaging with these experiences. Behavioral activation might represent one mechanism by which physical activity interventions improve depression. Objective: To examine behavioral activation as a mechanism mediating the effects of physical activity intervention on depressive symptom improvement in individuals with MS. Methods: Mediational path analysis using data from a randomized controlled trial (N = 64) comparing telephone-based physical activity counseling (TC) to education (EC). Results: Participation in TC resulted in greater improvements in behavioral activation from months 0–3. Improvements in behavioral activation were associated with fewer baseline-adjusted depressive symptoms at month 6. The corresponding indirect (mediational) pathway was significant. Conclusion: Behavioral activation may represent one mechanism by which physical activity improves depression in MS. Future physical activity trials should capitalize on this relationship and place additional emphasis on identifying and engaging in personally meaningful life activity. Future trials of therapies focused on behavioral activation might benefit from encouraging physical activity goals. Trial registration: Trial Registration clinicaltrials.gov Identifier: NCT01198977.