Cognitive Correlates Of Fatigue In Pediatric-Onset Multiple Sclerosis

Fatigue is common in pediatric-onset multiple sclerosis (POMS), yet causal factors and correlates of fatigue are poorly understood in this population. A systematic review of fatigue and cognition was conducted in Chapter 2. The available evidence confirms that fatigue is a common symptom in POMS with rates in samples varying from 9-76% and symptoms typically severe and functionally impairing for POMS patients. The relationship between parent- and self-reported fatigue and cognitive performance is not consistently found in the literature, though higher levels of fatigue tend to associate with performance on measures of sustained visual attention and task switching.

In Chapter 3, we investigated associations between cognitive and clinical features of POMS, namely objective fatigability, and subjective fatigue. Fatigability was operationalized as response time variability on a brief version of the Continuous Performance Test (CPT). We found that there is a significantly greater probability of parents and participants endorsing severe fatigue in POMS relative to age- and sex-matched healthy controls (HCs). We also identified that POMS were less accurate and more variable in their performance on the CPT relative to HCs. We did not however observe the expected associations between performance-related fatigability on the CPT and severe levels of parent- and self-reported fatigue. Finally, diffusion tensor imaging was used to explore neural correlates of fatigability. POMS participants demonstrated lower whole brain white matter integrity relative to HCs and while generally in the expected direction, white matter integrity was not significantly associated with fatigability on the CPT.

Until there is a cure for MS, it is essential that we continue to understand fatigue and its correlates in this population in order to develop targeted interventions, increase quality of life, and minimize the secondary impacts of fatigue.