Relationship of Changes in Physical Activity to Fatigue and Depression in Pediatric Multiple Sclerosis

Background: Fatigue and depression are common symptoms of pediatric multiple sclerosis (MS). Whether modifiable behaviors, such as physical activity, influence fatigue and depression in this patient population is unclear.

Objectives: We evaluated the relationship between changes in physical activity and the evolution of fatigue and depression over time in pediatric patients with MS and monophasic acquired demyelinating syndromes (mono-ADS).

Methods: Physical activity, fatigue, and depression were assessed at baseline and 6-12 months later using standardized questionnaires in consecutive children (age 5.8-17.7 years) with MS (n=27) and mono-ADS (n=29) attending a pediatric MS clinic in Toronto, Canada. Questionnaires queried physical activity (Godin Leisure Time Exercise Questionnaire), fatigue (Varni PedsQL), and depression (CES-DC). Changes in physical activity, fatigue, and depression over time and their interactions were compared within and between MS and mono-ADS cohorts using Fisher’s exact test, Mann-Whitney U test, Wilcoxon signed-rank test, and Spearman correlation analysis. This study was approved by the institutional research ethics committee. 

Results: MS patients reported lower total physical activity at baseline (40.0(39.0) vs. 63.0 (44.0) metabolic equivalents (METs), p=0.02) and at follow-up (40.0(41.5) vs. 56.0 (50.5) METs, p=0.10), as well as less strenuous physical activity at baseline (18.0(31.5) vs. 27.0(36.0) METs, p=0.09) and follow-up (9.0(27.0) vs. 27.0(33.8) METs, p=0.04) compared to mono-ADS. MS patients reported higher fatigue scores (general fatigue: 7.0(7.0) vs. 5.0(7.5), p=0.07; total fatigue: 25.0(16.0) vs. 16.0(21.0), p=0.08) than mono-ADS patients at follow-up. MS patients also reported higher depression scores at baseline (15.0(12.0) vs. 9.0(7.0), p=0.04) and follow-up (15.0(19.0) vs. 6.0(10.0), p=0.001). Furthermore, MS patients exhibited a trend toward worsening depression (+2.0(7.0), p=0.09) compared to a trend toward improvement in Mono-ADS patients (-3.0(7.5), p=0.11). In the MS cohort, decreased total physical activity correlated with greater fatigue at follow-up (ρ=-0.5 to -0.4, p<0.05). Similarly, decreased strenuous physical activity and HCS correlated with greater fatigue (ρ=-0.6 to- 0.4, p<0.05) and depression (ρ=-0.4, p<0.05) at follow-up. 

Conclusions: Decrease in physical activity is associated with greater fatigue and depression in pediatric MS patients. Limitations of this study include small sample size and observational design precluding inferences of causality. Future interventional studies may clarify the relationship of physical activity to fatigue and depression in this population.