Dr. Norby et al. performed a cross-sectional analysis of 2,517 participants in the population-based Atherosclerosis Risk in Communities (ARIC) study who wore a 2-week ambulatory continuous electrocardiography (ECG) recording device to determine whether nonsustained ventricular arrhythmia (NSVT) and premature ventricular contractions (PVCs) were associated with dementia. Whereas they found no overall association between NSVT and dementia, NSVT was associated with 3.67 times higher adjusted odds of dementia among Black participants; odds were also higher in this subgroup with an increasing burden of PVCs. In response, Dr. Fisher agrees that brain hypoperfusion may underly the observed relationship between ventricular arrhythmia and dementia and cites prior work showing PVC-associated reductions in peak, mean, and diastolic velocities in the middle cerebral artery using transcranial Doppler ultrasonography. Similar observations were made with atrial fibrillation, with dramatic changes before and after cardioversion. Responding to these comments, the authors agree that these physiologic findings offer mechanistic perspectives on their epidemiologic observations. This exchange highlights how epidemiologic and physiologic studies are synergistically advancing our knowledge of the heart-brain connection in dementia.