Hamilton, ON – McMaster University researchers have found a strong association between atrial fibrillation (AF) – an irregular heartbeat – and an increased risk of dementia.

While it’s known AF raises the risk of dementia among stroke survivors, the new study found this link is evident in individuals with AF who have not yet suffered a stroke.

The research, conducted by the Population Health Research Institute (PHRI) at McMaster University, appears in the current issue of the Canadian Medical Association Journal (CMAJ).

The authors of the study say it provides prospective evidence that atrial fibrillation increases the risk of cognitive decline and dementia, independent of clinically overt stroke and baseline cognitive function. They also saw a significant association between atrial fibrillation and functional decline (loss of independence with activities of daily living) and the need for long-term care.

Atrial fibrillation affects approximately 350,000 Canadians, according to the Heart and Stroke Foundation of Canada.

In their study, McMaster researchers sought to understand if there was an association between irregular heartbeat and the loss of mental and physical functions in people at risk of cardiovascular disease.

They looked at data from two randomized controlled trials, the ONTARGET and TRANSCEND trials which involved 31,546 patients from 733 centres in 40 countries. Participants were 55 years of age and older with cardiovascular disease or diabetes, and some organ damage from their disease.

The researchers assessed cognitive function at the outset, after two years and at a patient’s second last appointment. To gauge attention, ability to calculate, recall, name, repetition, read and comprehension, they used the mini-mental state examination (MMSE) which determined decline, onset of dementia or functional decline.

“The composite outcome of a decline in MMSE score by three or more points, dementia, admission to long-term care facility and loss of independence in performing activities of daily living occurred in 26 per cent of patients without atrial fibrillation and in 34 per cent of patients with atrial fibrillation,” said Dr. Koon Teo, professor of medicine in the Michael G. DeGroote School of Medicine at McMaster University and PHRI associate director.

The researchers conclude their findings highlight the need to include cognitive and functional measures in clinical trials of patients with atrial fibrillation.

Source: McMaster University