Flexibility of brain dynamics is increased and predicts clinical impairment in Relapsing-Remitting but not in Secondary Progressive Multiple Sclerosis

Abstract

ABSTRACTBackgroundLarge-scale brain activity has long been investigated under the erroneous assumption of stationarity. Nowadays, we know that resting state functional connectivity is characterised by aperiodic, scale-free bursts of activity (i.e. neuronal avalanches) that intermittently recruit different brain regions. These different patterns of activity represent a measure of brain flexibility, whose reduction has been found to predict clinical impairment in multiple neurodegenerative diseases such as Parkinson’s disease, Amyotrophic Lateral Sclerosis, and Alzheimer’s disease. Brain flexibility has been recently found increased in Multiple Sclerosis (MS) but its relationship with clinical disability remains elusive. Also, potential differences in brain dynamics according to the MS clinical phenotypes remain unexplored so far.MethodsWe studied brain flexibility through source-reconstruction of magnetoencephalography (MEG) signals in a cohort of 25 MS patients (10 RRMS and 15 SPMS) and 25 healthy controls (HC).ResultsRRMS patients showed greater brain flexibility than HC. On the contrary, no differences in brain dynamics were found in SPMS patients as compared to HC. Finally, brain dynamics showed a different predictive power on clinical disability according to the MS type.ConclusionFor the first time, we investigated brain dynamics in MS patients through high temporal resolution techniques, unveiling differences in brain flexibility according to the MS phenotype and its relationship with clinical disability.