Common blood thinning drugs can halve the risk of dementia among people with an irregular heartbeat, scientists have found.
A study of 440,000 people found patients who took warfarin and other clot busters were 48 per cent less likely to develop dementia over a decade.
Abnormal heart rhythm, known as atrial fibrillation, affects an estimated 900,000 patients in England.
The condition greatly increases the risk of stroke and early death, and patients are also more likely than others to develop dementia.
This is thought to be because tiny blood clots form in the head, stopping the flow of oxygen to the brain.
A study has shown that patients with an irregular heartbeats are 48 per cent less likely to develop dementia if they persist in taking blood thinning drugs. File image used
Most people with atrial fibrillation are prescribed blood thinners – such as warfarin, edoxaban or rivaroxaban – yet many choose not to take the drugs or stop taking them after a few years.
But Swedish experts last night said their discovery might persuade more people to stick with them.
Their findings, published in the European Heart Journal, revealed that those who took blood thinners for the nine years they were followed were 48 per cent less likely to develop dementia than those who never took the drugs.
The researchers, from the Karolinska Institute in Stockholm, believe this is because the drugs break down the clots, increasing blood flow to the brain.
Study leader Dr Leif Friberg, associate professor of cardiology at the Karolinska Institute, said: ‘Doctors should not tell their patients to stop using oral anticoagulants without a really good reason.
‘If you know that atrial fibrillation eats away your brain at a slow but steady pace and that you can prevent it by staying on treatment, I think most patients would find this a very strong argument for continuing.’
He added: ‘As a clinician I know there are atrial fibrillation patients who have a fatalistic view upon stroke. Either it happens or it does not.
‘Few patients are fatalistic about dementia. No brain can withstand a constant bombardment of microscopic clots in the long run.’
Irregular heartbeats, or atrial fibrillations, affect 900,000 patients in England, which mean the study could have a huge effect on UK healthcare
The researchers found many patients with an irregular heartbeat do not stick with the drugs.
Some 54 per cent of those they tracked were not taking the anticoagulants at the start of the study.
And every year another 10 to 15 per cent stopped taking the treatments.
But he stressed that people without atrial fibrillation should not be tempted to take blood thinners – because they can cause severe side effects such as brain haemorrhages.
Commenting on the study, Dr Carol Routledge, of Alzheimer’s Research UK, said: ‘The findings highlight a need to investigate this link further, but the nature of the study prevents us from firmly concluding that anticoagulants reduce the risk of dementia.’