Brain network changes and cognitive function after cardiac arrest

Survival rates after out-of-hospital cardiac arrest (OHCA) have improved over the past two decades. Despite this progress, long-term cognitive impairment remains prevalent even in those with early recovery of consciousness after OHCA; however, little is known about the determinants and underlying mechanisms. We utilized the REcovery after cardiac arrest surVIVAL (REVIVAL) cohort of OHCA survivors who fully regained consciousness to correlate cognition measurements with brain network changes using resting state functional MRI and the Montreal Cognitive Assessment (MoCA) at hospital discharge and a comprehensive neuropsychological assessment at three-month follow-up. About half of OHCA survivors displayed cognitive impairments at discharge, and in most, cognitive deficits persisted at three-month follow-up, particularly in the executive and visuospatial functions. Compared to healthy controls, OHCA survivors exhibited increased connectivity between resting-state networks, particularly involving the frontoparietal network. The increased connectivity between the frontoparietal and visual network was associated with less favorable cognitive outcomes (β=14.0, p=0.01), while higher education seemed to confer some cognitive protection (β=-2.06, p=0.03). In sum, the data highlight the importance of subtle cognitive impairment, also in OHCA survivors who are eligible for home discharge, and the potential of fMRI to identify alterations in brain networks correlating with cognitive outcomes.