Functional Connectivity Linked to Cognitive Recovery After Minor Stroke

Patients with minor stroke exhibit slowed processing speed and generalized alterations in functional connectivity involving frontoparietal cortex (FPC). The pattern of connectivity evolves over time. In this study, we examine the relationship of functional connectivity patterns to cognitive performance, to determine neurophysiological underpinnings of improvement, and whether connectivity profiles may be useful in evaluating and predicting longer-term cognitive outcomes.

Patients hospitalized with a minor ischemic stroke (NIH Stroke Scale < 10) were neurologically evaluated approximately 1 month following discharge. A battery of neuropsychological tests was administered to assess performance across multiple cognitive domains. Functional connectivity was evaluated using resting state magnetoencephalography (MEG). Repeat evaluations were performed 3-6 months later. The Network Localized Granger Causality framework was used to estimate functional connectivity at each visit. Relationships between functional connectivity and cognitive performance at each visit were assessed using cluster-based permutation tests and mixed effects modeling.

Forty-nine patients had available data for both follow-up visits. The average age was 62.4 years; 57% were female; 39% were Black. Mixed effects models indicated significant increases in contralesional frontoparietal beta-band connectivity across visits that corresponded to improved behavioral performance. Early reliance on the contralesional hemisphere was associated with better scores at visit 1, and continued reliance on areas within the ipsilesional hemisphere was associated with poorer performance at visit 2.

Specific connectivity profiles are associated with better acute and longer-term cognitive performance and may indicate greater potential for recovery. Further studies are needed to determine if patterns are modifiable.