An individual who has had a stroke and also suffers from atrial fibrillation (irregular heartbeat) has twice the risk of developing dementia compared to other people, researchers from the University of East Anglia, England revealed in the journal Neurology. Their study found that a stroke survivor who also has an irregular heartbeat has 2.4 times the likelihood of developing dementia compared to stroke survivors who have no heart condition.

The authors gathered data from over 15 studies involving over 45,000 individuals with an average age of 72 years. Patients with and without irregular heartbeats were compared, and also followed-up to find out which group was more likely to eventually develop dementia.

They discovered that approximately one-quarter of those who had survived a stroke and also had atrial fibrillation eventually developed dementia.

Dr Phyo Myint, lead author, wrote:

“These results offer convincing evidence of a link between irregular heartbeat and dementia in patients with stroke and could help us identify treatments that delay or even prevent the onset of dementia.

Options include more rigorous management of cardiovascular risk factors or of atrial fibrillation, particularly in stroke patients.”

The researchers informed that their high-quality meta-analysis is the only study of its kind ever to examine the potential role of atrial fibrillation in dementia risk. Dr Myint added that signs of an association in the general population – which some earlier studies had suggested – were inconclusive. “There remains considerable uncertainty about any link in the broader population.”

The older we get the higher are our chances of suffering from atrial fibrillation. Approximately 5% of British over-65s are affected. Over two million Americans have irregular heartbeats. About 750,000 people in the UK have dementia, which is estimated to be the cause of 60,000 premature deaths every year.

Over the next four decades the total number of people with dementia is expected to go up by about 150%. Much about dementia is still a mystery, experts believe that the risks of developing it are down to many factors, such as hypertension, diabetes, smoking, and age.

The human heart consists of four chambers: Two upper chambers called:

  • The left atrium
  • The right atrium

And two lower chambers called:

  • The left ventricle
  • The right ventricle

The plural of “atrium” is “atria”. If the two upper chambers contract too at too high a rate, and irregularly, the individual has atrial fibrillation, often termed irregular heartbeat. There is quivering instead of a coordinated contraction. Fibrillation means “quivering”.

With atrial fibrillation, the heart’s two upper chambers are not synchronized with the contractions of the two chambers below. This often results in poor blood flow to the body, considerably increasing the risk of stroke. In about 1 in every 7 cases of stroke, the patient has had atrial fibrillation. Stroke risk is also higher among individuals who smoke, lead a sedentary lifestyle, and those with hypertension (high blood pressure).

Atrial fibrillation is the most common arrhythmia – problems with the rhythm or speed of the heartbeat. It is caused by a fault in the heart’s electrical system.

The authors say that in order to determine whether the link between atrial fibrillation and dementia in stroke patients was casual, further high quality research is needed.

Dr Susanne Sorensen of the Alzheimer’s Society, said:

“This important research suggests that those with atrial fibrillation who have previously had a stroke need to be identified and monitored more closely. We now need more research involving stroke survivors with this type of cardiovascular disease to determine whether controlling atrial fibrillation with medication could reduce the risk of getting dementia later in life.

“Cardiovascular disease and stroke are well known risk factors for dementia. The best way to reduce risk of dementia is to take regular exercise, maintain a healthy weight, eating a healthy diet rich in fruit and vegetables and ensuring that your blood pressure and cholesterol are checked regularly.”

“Atrial fibrillation and incidence of dementia – A systematic review and meta-analysis”
C.S. Kwok, MSc, Y.K. Loke, MD, R. Hale, BSc, J.F. Potter, DM and P.K. Myint, MD
Neurology March 8, 2011 vol. 76 no. 10 914-922 doi: 10.1212/WNL.0b013e31820f2e38

Written by Christian Nordqvist