A phase 3 study investigated the association between atrial fibrillation and cognitive decline. It showed no effect of the anticoagulant drug rivaroxaban on the risk of cognitive decline. This drug has been administered to individuals with atrial fibrillation and low thromboembolic risk. The results indicate the need for a better understanding of the mechanisms linking these conditions. The study was published in Nature Medicine online on January 7, 2026. The article's DOI is 10.1038/s41591-025-04127-2.