An estimated five million Americans have atrial fibrillation (AFib), the uncoordinated beating of the hearts upper chambers. With AFib, not all of the blood in the atria is pumped out, so it can pool and form clots, which in turn can interrupt blood flow to the brain, causing a stroke. A study reported in the Sept. 25 European Heart Journal found that atrial fibrillation also may be linked to dementia. Among 2,837 patients identified as having AFib in a Minnesota county, 299 developed dementia-a rate three times higher than residents age 50 and older without AFib. Cleveland Clinic cardiac surgeon Marc Gillinov, MD, suggests that the cognitive decline shown in the test subjects could be the result of multiple disruptions of blood flow to the brain. Stroke-related dementia is often referred to as vascular dementia.