Multiple sclerosis (MS) is a chronic inflammatory illness of the central nervous system that causes a wide range of physical and cognitive symptoms. At least 80% of people with MS report a heightened perception of fatigue, and nearly half report that fatigue is their most disabling symptom, with debilitating consequences for quality of life and employment (Loy et al., 2017; Manjaly et al., 2019). Causes of MS fatigue are still poorly understood and likely multifactorial (Manjaly et al., 2019): Combination of mechanisms including structural brain damage and inflammatory processes have been proposed to affect interoceptive function and autonomic nervous control, alter network recruitment and activity during a physical task, with reduction in supply of monoaminergic neurotransmitters and orexin to specific areas of the brain.
The present PhD project aims to contribute to a deeper understanding of the neuropsychophysiology of fatigue perception in MS patients through the testing of an exercise-focused model based on predictive coding currently under development in our laboratories. Symptom of fatigue may worsen or be alleviated following exercise in MS patients depending on disease stage and exercise type (Millet and Soundry, 2017; Smith et al., 2009). Physical exercise will be used in this PhD to manipulate experimentally fatigue perception. Perceptions of effort, affect and pain will be investigated for their potential interactions with fatigue perception and muscular performance.
Our laboratories hold expertise in the measure of fatigue that develops within the exercising muscles and the central nervous system during physical exercise (i.e. peripheral and central origins of ‘muscle fatigability’). Our laboratories are also interested in both concept of interoception and autonomic regulation which could also be of interest within the present research project. Finally, there is scope for the project to expand beyond perceptual, autonomic and muscular measures, for the study of functional cortical network.
Loy, B. D., Taylor, R. L., Fling, B. W. and Horak, F. B. (2017) 'Relationship between perceived fatigue and performance fatigability in people with multiple sclerosis: A systematic review and meta-analysis', J Psychosom Res, 100, pp. 1-7.
Manjaly, Z. M., Harrison, N. A., Critchley, H. D., Do, C.T., Stefanics, G., Wenderoth, N., Lutterotti, A., Muller, A., Stephan, K. E. (2019). 'Pathophysiological and cognitive mechanisms of fatigue in multiple sclerosis', J Neurol Neurosurg Psychiatry, 90(6), pp. 642-651.
Miller, P. and Soundy, A. (2017) 'The pharmacological and non-pharmacological interventions for the management of fatigue related multiple sclerosis', J Neurol Sci, 381, pp. 41-54.
Smith, C., Hale, L., Olson, K. and Schneiders, A. G. (2009) 'How does exercise influence fatigue in people with multiple sclerosis?', Disability and Rehabilitation, 31(9), pp. 685-692.