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Experts say atrial fibrillation should be treated due to the health conditions it can bring on. Luis Alvarez/Getty Images
  • Researchers report that people diagnosed with atrial fibrillation (AFib) at or before age 65 are more likely to be diagnosed with dementia than those diagnosed after age 65.
  • AFib can also lead to other health conditions, such as stroke, mood changes, and cognitive deficits.
  • Experts say treating AFib can reduce the risk of dementia.

People with atrial fibrillation (AFib) are more likely to develop dementia, according to a new research published in the journal JAMA Network Open.

There were 433,746 participants in the study with 30,601 having AFib. In a follow-up period of more than 12 years, the researchers noted 5,898 new-onset dementia cases, 1,031 of which were diagnosed in participants with AFib.

Researchers reported that participants who were 65 or younger when diagnosed with AFib had a higher risk of developing all-cause dementia, Alzheimer’s disease, and vascular dementia.

Those who were diagnosed at 75 or older had the lowest risk of all-cause dementia.

The study did have a large sample size, but researchers noted its limitations included:

  • It was observational only – cause and effect could not be determined.
  • 94% of participants were white, meaning the results can’t be generalized to other races and ethnicities.
  • There could have been selection bias after researchers excluded people who did not match the criteria.

“This is a very important study. The results are consistent with other studies. but this one is much larger in scope,” said Dr. Shephal Doshi, a cardiac electrophysiologist and director of cardiac electrophysiology and pacing at Providence Saint John’s Health Center in California who was not involved in the study. “And it adds information on the potential of harm to the heart from AFib.”

A study published in the journal JACC: Advances in October 2023 reported that AFib was associated with an increased risk of mild cognitive impairment and progression to dementia.

Researchers identified 233,833 people with AFib in a United Kingdom primary electronic health records database. During a 5-year follow-up, there were 4,269 cases of mild cognitive impairment in both people with AFib and those without the condition.

The researchers found that people with AFib had a 45% increased risk of mild cognitive impairment. Those with AFib who developed cognitive impairment also had a 25% increased risk of going on to develop dementia.

However, people treated with digoxin or other anticoagulants for AFib did not have an increased mild cognitive impairment risk.

Individuals with AFib and mild cognitive impairment had the most significant risk of dementia.

Some complications of AFib are cognitive decline, including AFib-related cerebral infarction, hypoperfusion, inflammation, atherosclerotic vascular disease, microhemorrhage, and brain atrophy, according to Dr. Brian H Kim, an electrophysiology lab director at Providence St Jude Medical Center in California who was not involved in the study.

AFib can also increase the risk of stroke, experts note.

“The connection to dementia could arise from clots that disperse throughout the brain from the left atrium,” Dr. Aseem Desai, a cardiologist/electrophysiologist with Providence Mission Hospital in California who was not involved in the study, told Medical News Today. “Other causes of stroke include blocked arteries, which affect specific circulation and cause specific deficits.”

The symptoms of AFib include:

Some people don’t have symptoms.

“Atrial fibrillation is an irregular and sometimes rapid heartbeat that can lead to the formation and propagation of blood clots leading to stroke, heart failure, and other heart-related problems,” said Dr. Shae Datta, the co-director of NYU Langone’s Concussion Center in New York and director of cognitive neurology at NYU Langone Hospital — Long Island. “Atrial fibrillation alters blood flow through the body, including to and from the brain, which could lead to cerebral injury and disruption of the blood-brain barrier.”

“People with AFib can have multiple strokes, including silent strokes,” Datta, who was not involved in the study, told Medical News Today. “Silent strokes don’t show physical symptoms and later can be detected on brain scans, contributing to dementia. This makes prevention and treatment very important.”

Experts said that in the past, doctors treated AFib only when it caused symptoms.

“This study shows us the condition causes heart problems when not treated – even in the absence of symptoms,” Doshi told Medical News Today. “When people have AFib, they have an irregular heartbeat, which could result in a small drop in oxygen to the brain. This might not be a problem once or twice, but it can build up and result in years of less oxygen and damage to the brain. When people are diagnosed younger they have more years for it to build up.”

“It can be dangerous if you don’t feel the irregular heartbeat or don’t have any symptoms. Treatments such as blood thinners or ablation can help but are only used when symptoms are disruptive,” Doshi added. “This study tells us that we should look for and treat AFib before the damage is done.”

Experts say that this research, including the current study, shows that treating AFib can lower the risk of developing dementia.

“A number of studies have linked atrial fibrillation to cognitive decline and/or dementia. Although there have been many proposed mechanisms of causation, such as impaired cerebral blood flow, increased inflammation, and microhemorrhages, the most likely cause is recurrent silent cerebral infarcts,” said Dr. Kabir Bhasin, a cardiac electrophysiologist in the Cardiology/Internal Medicine at Northwell Health who was not involved in the study. “We are, obviously, aware that atrial fibrillation can lead clot formation in the heart. These clots can then migrate (embolize) to the brain and cause strokes/infarcts with overt and dramatic clinical findings. However, there is a growing body of evidence, based mostly on brain MRIs, that patients with AFib suffer recurrent mini-embolic events. These emboli are too small to have any overt clinical impact individually but their accumulation over time can, it is theorized, lead to dementia.”

“Preventing clot formation may help prevent dementia,” Bhasin told Medical News Today. “Recent studies have shown that use of the newest generation of blood thinners, collectively known as the DOACs (direct oral anticoagulants), did decrease the risk of developing dementia. What we do not yet know is does catheter ablation, a procedure in which we attempt to cure atrial by burning or freezing portions of the heart, help prevent cognitive decline. There are some population-based studies from Korean and Taiwan that show patients who have an ablation have a lower rate of dementia, but it is difficult to extract a causal relationship from these kind of studies. There are a number of studies currently being planned that will hopefully answer this question soon.”