White matter integrity and functional connectivity of the default mode network in acute stroke are associated with cognitive outcome three months post-stroke

Background: Knowledge about factors that are associated with post -stroke cognitive outcome is important to identify patients with high risk for impairment. We therefore investigated the associations of white matter integrity and functional connectivity (FC) within the brain 's default -mode network (DMN) in acute stroke patients with cognitive outcome three months post -stroke. Methods: Patients aged between 18 and 85 years with an acute symptomatic MRI-proven unilateral ischemic middle cerebral artery infarction, who had received reperfusion therapy, were invited to participate in this longitudinal study. All patients underwent brain MRI within 24 -72 h after symptom onset, and participated in a neuropsychological assessment three months post -stroke. We performed hierarchical regression analyses to explore the incremental value of baseline white matter integrity and FC beyond demographic, clinical, and macrostructural information for cognitive outcome. Results: The study cohort comprised 34 patients (mean age: 64 +/- 12 years, 35% female). The initial median National Institutes of Health Stroke Scale (NIHSS) score was 10, and significantly improved three months poststroke to a median NIHSS = 1 ( p < .001). Nonetheless, 50% of patients showed cognitive impairment three months post -stroke. FC of the non-lesioned anterior cingulate cortex of the affected hemisphere explained 15% of incremental variance for processing speed ( p = .007), and fractional anisotropy of the non-lesioned cingulum of the affected hemisphere explained 13% of incremental variance for cognitive flexibility ( p = .033). Conclusions: White matter integrity and functional MRI markers of the DMN in acute stroke explain incremental variance for post -stroke cognitive outcome beyond demographic, clinical, and macrostructural information.