Physical activity and functional limitations in pediatric multiple sclerosis: Are fatigue and depression confounding variables?

Purpose: Pediatric-onset multiple sclerosis (MS) is associated with risk for functional limitations defined as the perceived reduction in capacity for undertaking activities of daily living. Moderate-to-vigorous physical activity (MVPA) has been associated with less frequent and less impactful functional limitations, but the symptoms of fatigue and depression have not been considered as potential confounding variables. This study examined whether fatigue and depression confound the association between MVPA and functional limitations among youth with pediatric MS. Methods: Participant data were accumulated from three ongoing observational studies. The combined sample included 65 cases of pediatric-onset MS (24 male/41 female, 16±1.7 years of age). Data on self-report MVPA, functional limitations, depression, and fatigue were analyzed. Results: MVPA was significantly associated with functional limitations (r = 0.45), fatigue (r = –0.28), and depression (r = –0.32). Functional limitations were associated with fatigue (r = –0.45) and depressive symptoms (r = –0.53). MVPA was significantly correlated with functional limitations (β= 0.27, p = 0.04) even after accounting for general fatigue (β= 0.08, p = 0.64) and depressive symptoms (β= –0.40, p = 0.03) among those with pediatric MS. Conclusion: Self-reported MVPA was associated with perceived functional limitations among youth with pediatric MS independent of perceived fatigue and depressive symptoms.