Stroke Survivors with Atrial Fibrillation May Have Increased Dementia Risk
A heart condition known as atrial fibrillation increases the risk of having a stroke. According to the American Heart Association, about 15% of strokes occur in people with the condition. For stroke survivors who have atrial fibrillation, it may also raise the risk of developing dementia, according to new research by the University of East Anglia in the UK.
Irregular Heartbeat Could Increase Risk of Blood Clots to Brain
During atrial fibrillation, the heart’s two upper chambers (the atria) quiver instead of beating effectively. This causes blood to be incompletely pumped out of the chambers, increasing the risk of blood pooling and clotting. If a blood clot leaves the heart and becomes lodged in an artery in the brain, a stroke results.
Researcher Phyo Kyaw Myint MD and colleagues reviewed 15 studies on the association between atrial fibrillation and dementia. The studies included data on 46,637 participants with an average age of 72. The researchers determined that of the total number of patients who had survived a stroke, those with atrial fibrillation were 2.4 times more likely to develop dementia than those with normal heart rhythms.
“These results may help us identify potential treatments that could help delay or even prevent the onset of dementia,” says Dr.Myint. “Options could include more rigorous management of cardiovascular risk factors or of atrial fibrillation, particularly in stroke patients.”
Both atrial fibrillation risk and the risk of developing dementia increase with age. The AHA states that three to five percent of people over the age of 65 have atrial fibrillation. According to the Alzheimer’s Association, the risk of developing dementia doubles every five years after age 65.
The researchers speculate that the reason or dementia risk with a-fib could be that fluctuations in cardiac output add to thromboembolic damage and chronic under-perfusion of the brain. Ischemia may also increase the expression of dementia-related amyloid precursor proteins, they suggest.
"There is a possibility that atrial fibrillation may be a prominent risk factor for dementia or cognitive impairment in certain patients without stroke, but not for those aged over 80 years, whose dementia may mainly be due to other pathologies," they explained in the paper.
Patients with atrial fibrillation can reduce their risk of stroke by having the condition appropriately treated medically. This includes anticoagulant and antiplatelet medications which can reduce the risk of stroke by 68%.
Kwok CS, et al "Atrial fibrillation and incidence of dementia: A systematic review and meta-analysis" Neurology 2011; 76: 914–922.