Abstract
<title>Abstract</title> <p>Atrial fibrillation (AF) is associated with cognitive impairment that cannot be fully explained by embolic injury, implicating additional mechanisms. We hypothesised that the irregular heartbeat during AF induces an interoceptive overload affecting cognition. In this cross-sectional UK Biobank analysis, we assessed cognitive performance alongside resting-state and diffusion MRI connectomes in 246 AF cases and 492 controls matched on demographics, cardiovascular risk, and white matter hyperintensity (WMH) burden. Despite WMH matching, AF was associated with a selective reduction in processing speed, stable across WMH locations. Functionally, AF exhibited whole-brain dedifferentiation (reduced segregation, increased participation) and increased connectivity within a right-lateralised subnetwork overlapping the allostatic–interoceptive system (replicated in an internal held-out sample), without corresponding structural-connectivity differences. Within AF but not controls, greater deviation of subnetwork connectivity from controls predicted faster processing speed in cross-validated models, consistent with compensatory recruitment. These findings provide an explanation for AF-related cognitive impairment beyond embolic injury, implicating altered brain–body interactions.</p>