A COMMON heart rhythm issue increases the risk of developing dementia, scientists have warned.

Atrial fibrillation (sometimes called afib or AF) is a type of heart rhythm problem where a person’s heartbeat doesn’t beat steady.

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The condition itself usually isn’t life-threatening, but can lead to stroke if left untreated.

Now, a new study presented at the EHRA 2025, a scientific congress of the European Society of Cardiology, suggests its negative impact on brain health.

According to the findings, AF increases the risk of future dementia by 21 per cent in patients diagnosed with the condition under the age of 70, and the risk of early-onset dementia (diagnosed before the age of 65) by 36 per cent.

The association was found to be stronger in younger adults and was lost in adults aged 70 years and over.

“This is the largest European population-based study evaluating the association between AF and dementia,” say the authors that include Dr Julián Rodriguez García of the Electrophysiology and Arrhythmia department of the Bellvitge University Hospital, Barcelona, Spain. 

“The association between AF and dementia was stronger in patients under 70 and was maximal for early-onset dementia.” 

In the UK, an estimated 1.4 million people are affected by AF – and the risk increases with age.

While there’s currently no cure for AF, effective treatments can manage symptoms and reduce the risk of complications.

To potentially avoid or reduce the risk of AF, you should focus on a heart-healthy lifestyle – maintain a healthy weight, engage in regular physical activity, manage stress, control blood pressure and cholesterol, quit smoking, and limit alcohol and caffeine intake. 

In the new study, researchers assessed the independent association between AF and incident dementia in Catalonia, Spain.

A total of 2,5250,839 individuals took part, and there was an average follow-up of 13 years.

At baseline, 79, 820 patients (3.25 per cent) had a record diagnosis of AF.

AF was, overall, a statistically significant but weak predictor of dementia, linked with a 4 per cent increased risk of dementia.  

But age was found to significantly affect the associated between AF and dementia.

The strength of the association progressively weakened with increasing age – in patients aged 45-50, those with AF were 3.3 times more likely to develop dementia than those without AF. But in patients aged over 70 years, no association was found.  

In patients diagnosed with AF before the age of 70, the condition independently increased the risk of dementia by 21 per cent, and even stronger effect was observed for early-onset dementia, with AF increasing the risk by 36 per cent.

The authors said: “Dementia is often a multifactorial condition with mixed neuropathological findings rather than a single pathophysiological process.

“This may explain why AF has a greater impact in younger patients, where it could be one of the primary pathogenic factors.

“Conversely, in older individuals, additional contributors to cognitive decline—such as age-related neurodegeneration—may lessen the relative impact of AF.” 

Also, patients with AF without a prior risk of stroke still had a higher risk of dementia, with the greatest risk observed in early-onset dementia.

The authors said: “Atrial fibrillation is a risk factor for stroke and stroke is a risk factor for dementia.

“However, the observation that the association between AF and dementia remains unchanged after excluding patients with prior stroke indicates that other mechanisms must be involved in the increased risk of dementia among AF patients.

“These mechanisms may include silent strokes – meaning those that showed no clinical symptoms and can only diagnosed with CT scan or MRI – and also microinfarcts, and microbleeds.”   

Overall, the researchers concluded the study demonstrates a significant and strong association in younger patients with AF and dementia – which are among the health challenges of the 21st century,

They added: “We should now investigate whether early detection strategies and aggressive management of atrial fibrillation in younger patients can help reducing the risk of dementia and changing the natural course of the disease.” 

Atrial fibrillation explained

YOUR heart is controlled by a conduction system, which sends out electrical signals. This is what causes a heartbeat.

Atrial fibrillation is a type of arrhythmia – a problem with the conduction system that can make your heart beat too slowly, too quickly or in an irregular way.

Atrial fibrillation happens when the electrical signals in the top chambers (atria) of your heart do not get sent out properly.

They should be steady and regular, but instead they quiver or twitch (fibrillation).

This causes your heart to beat randomly, which means it does not pump blood as well as it should.

Atrial fibrillation is not life-threatening itself, but it can create blood clots in the heart that may cause a stroke.

Many people won’t experience any symptoms at all, but some have palpitations, chest pain, tiredness, shortness of breath and dizziness.

The cause is not always known, but the most common is damage to the heart.

This can be caused by things like high blood pressure, heart valve disease, coronary heart disease, obesity, stress and diabetes.

It is also associated with other medical conditions, including asthma, COPD, lung cancer and carbon monoxide poisoning.

But not everyone with atrial fibrillation is unwell, and it can sometimes affect people who are physically very fit, such as athletes.

Treatment may include medication, ablation, cardioversion and having a pacemaker fitted.

Source: British Heart Foundation