- A new study finds people with atrial fibrillation may be at higher risk for developing dementia.
- Though the mechanisms are unclear, some scientists suspect that atrial fibrillation may impact cerebral blood flow.
- This can increase the risk for brain injuries that affect cognitive functioning.
People with atrial fibrillation (AFib), a common cardiac arrhythmia, may have a higher risk of developing dementia, according to new research.
The study, published in the Journal of the American Heart Association Wednesday, found that younger people with atrial fibrillation had a significantly greater risk of dementia compared to older individuals and that cognitive decline was more prevalent in people without chronic kidney disease.
The report adds to growing evidence that atrial fibrillation is a risk factor for cognitive decline and dementia.
Though the mechanisms are unclear, some scientists suspect that atrial fibrillation may impact cerebral blood flow, increasing the risk for brain injuries that affect cognitive functioning.
Atrial fibrillation is also linked to a greater risk of stroke, and it’s well-known that cognitive impairment and memory loss are common after a stroke.
“There are theories as to whether AFib patients that have a higher rate of blood clots and strokes could develop dementia from this or whether AFib decreases the pumping function of the heart even slightly which over the years accelerated perfusion of the brain which can lead to dementia,” Dr. Shephal Doshi, a cardiac electrophysiologist and director of cardiac electrophysiology and pacing at Providence Saint John’s Health Center in Santa Monica, CA, told Healthline.
Atrial fibrillation appears to be a meaningful risk factor for dementia
The researchers evaluated nearly 200,000 adults in California over an average of about three and a half years.
About half of the participants had been diagnosed with atrial fibrillation.
The researchers then measured the incidence of dementia among the participants.
The incidence rate of dementia among people with atrial fibrillation was 2.79 per 100 person‐years and the incidence rate of atrial fibrillation among those without atrial fibrillation was 2.04 per 100 person‐years.
After adjusting for race, sex, and ethnicity, the team found that atrial fibrillation was associated with a 13% higher risk of dementia.
Adults under the age of 65 with atrial fibrillation had a 65% higher risk of developing dementia compared with older adults.
Chronic kidney disease was associated with a lower risk of dementia — those without the condition had a 14% higher risk of dementia than those with chronic kidney disease.
The researchers concluded that, independent of its association with stroke, atrial fibrillation may be a clinically-important risk factor for dementia among young, otherwise healthy people.
Here’s why atrial fibrillation may contribute to dementia
The leading theory is that atrial fibrillation may impact blood flow to the brain, which can damage white matter in the brain and lower cognition.
Studies supporting this theory have identified signs of cerebrovascular disease in people with atrial fibrillation along with higher rates of cerebral infarcts and white matter disease.
“There may be altered blood flow to the brain in AFib, and there may [also be] emboli (blood clots) or bleeding,” says Dr. Paul Wang, the director of Stanford Health Care’s Cardiac Arrhythmia Service.
People with atrial fibrillation also have a higher risk of stroke, and it has been well-known for years that strokes can contribute to cognitive decline.
Understanding risk factors
The medications used to treat atrial fibrillation — oral anticoagulation— and cerebral hypoperfusion are associated with cerebral infarcts and microbleeds, which could lead to cognitive decline.
“There may also be genetic factors and other causes of inflammation in the body,” Wang said.
There’s no conclusive evidence on these potential mechanisms, Doshi says.
Because the mechanisms are poorly understood, there are no proven preventative strategies against dementia for people with atrial fibrillation.
People with atrial fibrillation are often advised to take oral anticoagulation for stroke prevention, and the lower risk of stroke should lead to a lower risk of cognitive decline.
Many people try to correct irregular heart rhythms, Wang said.
This can be attempted through cardioversion — a procedure that uses low-energy shocks to restore irregular heart rhythm to a normal rhythm.
More studies on the potential mechanisms, and the effectiveness of treatment strategies to address them, are needed.
“We need research that would help us better understand the causative relationship between AFib and dementia,” says Doshi.
The bottom line:
People with atrial fibrillation (AFib), a common cardiac arrhythmia, have a higher risk of developing dementia, according to new research. The report adds to growing evidence that atrial fibrillation is a risk factor for cognitive decline and dementia. The mechanisms are unclear but researchers suspect reduced cerebral blood flow and a heightened risk of stroke in AFib patients contribute to cognitive decline.
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