Exploring Atrial Fibrillation and All-Cause Dementia: Implications for Primary Care Providers

Atrial fibrillation (AF) and dementia are 2 very prevalent and sometimes interconnected medical conditions that pose a significant challenge to the aging global population. AF, the most common cardiac arrhythmia, affects approximately 1 in 3 people worldwide.¹ Dementia, an impairing decline in cognitive function, affects 1 in 7 people.² Numerous causes of dementia, such as Alzheimer’s disease (AD) and thromboembolic strokes, are common sequelae of AF related to poor blood flow and clot formation.³ Several theories exist regarding the connection between AF and dementia, but recent research suggests that AF increases the risk for dementia even in patients without a history of overt stroke.⁴

Atrial Fibrillation

Atrial fibrillation, the most common cardiac arrhythmia, most frequently occurs in those over 60 years of age.¹ In a normal heart, the sinoatrial node, located in the atria, acts as the pacemaker by sending electrical signals that coordinate the heart’s contractions. In patients with AF, however, multiple sources within the atria send electrical signals, which leads to an irregular and chaotic heart rhythm. The irregular heart rhythm can reduce blood flow, leading to a gamut of issues, including ischemic strokes and hypoperfusion of organs.

AF can range in duration from a few seconds to several years and may present with or without symptoms, which can include palpitations, fatigue, dizziness, and shortness of breath.

Management of AF involves either rate control or rhythm control, along with prevention of thromboembolism.⁵ Rate control can be accomplished with pharmacologic agents, such as beta blockers, or via atrioventricular node ablation and pacemaker implantation. Rhythm control options include antiarrhythmic agents, such as amiodarone and dofetilide, and ablation.⁵   

Dementia

Dementia is described in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, Text Revision (DSM-5-TR) as a decline in cognitive function that impairs aspects of daily life, such as working, driving, and relationships. Per the DSM-5-TR, dementia is considered a major neurocognitive disorder, which means it can be diagnosed if there is a significant decline in just one such cognitive domain, such as perception, attention, language, memory, executive functions, and social cognition. Previously, a diagnosis was contingent on significant declines in multiple domains.⁶

Vascular dementia, a common type of dementia, refers to impaired memory, thinking, and behavior because of conditions that affect the blood vessels in the brain. AF is commonly associated with vascular dementia because it causes clots to form, which can travel to the brain, block blood flow, and cause an ischemic stroke.

AD is the most common cause of dementia, and while its exact pathophysiology remains unclear, recent research indicates that people with AF have a higher risk for developing AD.³ This is particularly intriguing, given that the mechanisms underlying each condition are believed to be quite different. 

Pathophysiology

Numerous studies provide evidence of a link between AF and dementia, with AF increasing the risk for vascular dementia as well as AD and other forms of dementia.^6-8 This indicates that the relationship between AF and dementia extends beyond just the occurrence of strokes. Various mechanisms have been hypothesized to explain the connection. Some hypotheses are more widely accepted than others, such as the idea that the thrombotic state associated with AF leads to cerebral infarcts.

Genetics

There is some evidence that AF and dementia are genetically related. Research has shown that multiple structural genes are associated with AF.⁹ One study showed that genetically predicted AF had a positive causal correlation for vascular dementia, but the correlation was neutral for AD and other causes of dementia, such as frontotemporal dementia and Lewy Body dementia.¹⁰ Although the evidence is intriguing, there is limited research on this connection, and it is not a widely accepted belief. 

Common Risk Factors 

As noted, AF is widely recognized as a risk factor for dementia because of its association with an increased risk for clot formation and subsequent ischemic strokes. However, MRI evidence has shown that AF is associated with cognitive impairment even in patients without history of a stroke.¹¹ This evidence is further supported by a study showing that the cumulative incidence of dementia in patients with AF without catheter ablation persistently increased in the years following the diagnosis of AF, whereas the incidence in those who did receive CA remained similar to patients without AF.¹²

According to the American Heart Association, although AF and dementia share common risk factors, such as older age, hypertension, smoking, and obesity, their association appears to be independent of these variables.¹¹ 

Anticoagulation Induced Hemorrhages

Another proposed mechanism of correlation is that prescribed anticoagulants for AF causes cerebral microbleeds, leading to dementia. However, several studies have shown that direct oral anticoagulants (DOACs) taken as prescribed significantly decrease the risk for dementia.¹³ Anticoagulants are associated with risk for bleeding, but patients with AF are much more likely to develop dementia if they do not take DOACs than if they do. Warfarin and heparin are associated with a higher risk for bleeding, so they have largely been replaced by the DOACs.¹⁴

Hypoperfusion

Another risk associated with AF is hypoperfusion because the heart is not squeezing and sending blood to the body as it should. To address this, antiarrhythmic medications can be prescribed to help prevent the extra electrical impulses that cause AF, and rate controlling agents, such as beta-blockers and calcium channel blockers (CCBs), can be used to slow the heart rate. Together, these medications can help increase stroke volume and cardiac output to improve perfusion throughout the body. Without these treatments, or if they are not effective, the patient may experience chronic hypoperfusion. Over time, hypoperfusion of the brain can result in central nervous system dysfunction and brain atrophy.¹⁵ This hypoperfusion is characteristic of vascular dementia; in contrast, brain atrophy is a key element of AD.¹⁶ 

Anxiety

A less researched mechanism of correlation is anxiety. Patients with AF are known to have anxiety due to the palpitations that the arrythmia can cause,¹⁷ and anxiety is known to worsen all-cause dementia.¹⁸ Atrial ablation to interrupt the chaotic electrical signals that make the heart quiver may be helpful in this setting. Ablation of the faulty atria has been shown to eliminate the palpitations and associated anxiety.¹⁹

Implications for Primary Care Providers

 Considering the prevalence of dementia in patients with AF, regardless of the physiological connection, it is important for primary care providers to watch for signs and symptoms of cognitive decline in patients with AF. The best proactive measure to avoid dementia and other issues that may be associated with AF is prescribing anticoagulants and attempting to control the rate and rhythm via medications or ablation.^20,21 Currently, neither screening for AF or prophylactically medicating AF patients for AD are recommended.^22,23 Of note, anticholinesterase inhibitors for AD, such as donepezil, may worsen the AF.²²

Although it is not recommended that primary care providers screen for AF or medicate for dementia proactively, providers should consider screening for dementia in AF patients. As per the US Preventive Services Task Force, there is not enough evidence to say whether the benefits of screening older adults for cognitive decline outweigh the risks.²⁴ However, several screening methods are available that pose little to no risk. Primary care providers could perform a baseline cognitive test when patients are diagnosed with AF. There are several free online resources that providers can use to quickly assess a baseline (ie, Montreal Cognitive Assessment, Mini-Mental State Examination, Saint Louis University Mental Status exam).

Providers should reassess the patient’s mental status every 6 months or so using the same test to make sure cognition is not declining. If a patient’s score declines, a more interdisciplinary approach could be adopted, involving collaboration among providers from various specialties. Measures could be implemented to prevent further cognitive decline and maintain or enhance the patient’s quality of life.

It is extremely important that primary care providers make an effort to optimize their AF patients’ medications. Controlling and balancing the rate, rhythm, and coagulation is crucial for these patients. Primary care providers also should consider their patient’s mental health, particularly assessing for anxiety and depression, which are common among those with AF. Anxiety can be a consequence of the fast heart rhythm, and it can make the arrythmia worse. Primary care providers could consider doing mental health screenings, such as Generalized Anxiety Disorder 7-item and Patient Health Questionnaire-9, along with cognition screenings.

Research indicates that younger patients diagnosed with AF have a higher risk of developing all-cause dementia. Therefore, primary care providers should remain vigilant for signs and symptoms of dementia in all AF patients, particularly those diagnosed before 65 years of age.²⁵ 

Key Takeaways

• Considering the burden of AF and dementia on the global population and how often these diseases occur together, it is important that primary care providers care for these patients proactively.
• Primary care providers are encouraged to implement a baseline cognitive health screening for patients diagnosed with AF, regardless of symptoms.
• It is crucial that providers ensure that medications such as anticoagulants, antiarrhythmics, and rate control agents are appropriately optimized for effective treatment.

This article originally appeared on Clinical Advisor