Fronto-parietal network dynamics to understand deficits in attention performance in multiple sclerosis

IntroductionImpaired attention performance is a significant burden to people with multiple sclerosis (MS). Brain connectivity fluctuates with transitions between cognitive states, so measurement of network dynamics during these conditions may help to understand MS-related attention impairment. MethodsIn people with MS and healthy controls, attention was measured using the Attention Network Test. 3T MRI was used to measure structural connectivity and both static and dynamic functional connectivity in the attention-related fronto-parietal network (FPN) at rest and during an attentionally-demanding task. Groups were compared on connectivity of the FPN during rest and task performance. Relationships between network connectivity and attention performance were tested using linear regression. ResultsThe sample comprised 37 people with MS and 23 matched controls. At rest, people with MS had significantly lower structural connectivity (R2=0.13, p=0.004), lower static functional connectivity (R2=0.07, p=0.032) and higher dynamic functional connectivity (R2=0.08, p=0.026) of the FPN. Higher dynamic connectivity was significantly associated with poorer attention performance in people with MS (R2=0.20, p=0.008). During attention-task performance, static functional connectivity was greater in people with MS than controls (R2=0.10, p=0.008). The task-induced reduction in static connectivity (relative to rest) was directly related to attention performance (R2=0.23, p<0.001). ConclusionIncreased dynamic functional connectivity of the FPN at rest may be a useful indicator of deficits in sustained attention in people with MS. The transition from rest to active-attentive state is accompanied by an increase in dynamic connectivity, and decrease in static connectivity which may be helpful in understanding aetiology and treatment of attention impairment.