You will never be able to escape from your heart. So it is better to listen to what it has to stay.” – Paulo Coelho, The Alchemist
New studies also suggest listening to what the heart has to say because sooner or later you will have to face its consequences. These studies show that atrial fibrillation, in which the heart beats irregularly, is linked to an increased risk of cognitive decline and dementia. This information also indicates a potential preventive strategy.
Introduction- Atrial fibrillation (AF) is the most common clinically significant arrhythmia in the world.  Over the coming years, the incidence of AF is expected to increase.  AF is a well-established risk factor for other cardiovascular diseases, including ischemic stroke and heart failure.  Growing evidence, however, indicates that AF can have harmful effects beyond an increased risk of cardiovascular diseases. Specifically, many recent studies have explored the impact of AF on cognition and dementia risk. With the aging population, the burden of dementia is expected to increase globally. A better understanding of the association of AF with dementia and cognitive impairment would help create strategies for the management of AF and the prevention of adverse cognitive outcomes among these patients.
Recent Studies – In a new study paper published in the journal Neurology, researchers at the Karolinska Institute and Stockholm University, which are in Sweden, explain that atrial fibrillation is linked with an increased risk of developing dementia. The most basic evidence supporting an association of AF with worse cognitive function comes from cross-sectional studies comparing cognition in individuals with and without AF. The prevalence of AF has been associated with Mild Cognitive Impairment (MCI) and impaired global cognitive function in cross-sectional studies in Europe and the US. Longitudinal studies with repeated assessment of cognitive function provide a more rigorous evaluation of the association of AF with cognition. An analysis of 31,506 participants found that those who had AF at baseline or developed it during the study had a 13 % increased risk of cognitive decline, defined as a decrease of three or more points in the Mini-Mental State Examination.  The published evidence is consistent in supporting an association between AF and cognitive outcomes. On the other hand, the mechanisms underlying this association still need clarification. An obvious pathway linking AF with cognitive decline or dementia is the elevated risk of stroke. AF is associated with at least a doubling of stroke risk  and the effects of stroke on cognitive function are well established.  In AF, the heart’s atria or the chambers that receive blood and then send it to the ventricles, which pump it out to the rest of the body beat irregularly. Because of this, blood can pool inside the heart and form clots, which may later circulate to the brain, leading to a stroke.  Despite this, elevated stroke risk does not completely mediate the increased risk of dementia and cognitive decline associated with AF.  Other mechanisms such as silent cerebral infarcts, microbleeds, and cerebral hypoperfusion are likely to play a role (Figure 1).
Figure 1: Potential Mechanisms Linking Atrial Fibrillation (AF) with Cognitive Decline and Dementia (Image adapted from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4988519/)
AF more than doubles the risk of silent cerebral infarcts independent of stroke  and the presence of silent cerebral infarcts is a risk factor for dementia.  Similarly, AF could increase dementia risk through its impact on cardiac function. Patients with AF have been found to have reduced cerebral perfusion;  and restoration of sinus rhythm in AF patients through cardioversion or ablation leads to improvements in cerebral blood flow. Reduced diastolic function and low cardiac index, both potential consequences of AF, have been associated with incident dementia in prospective studies. Moreover, AF is an established risk factor for heart failure, which in turn can worsen cerebral hypoperfusion. Microbleeds may also explain part of the association of AF with cognitive impairment. These brain lesions are relatively frequent and have been linked with an increased risk of cerebral hemorrhage, lacunar infarcts and degenerative changes in brain matter. 
Treatment – Participants in the study published in the journal Neurology with AF who took blood thinners to prevent blood clots actually had a 60% lower risk of developing dementia, compared with those who did not take this medication. At the same time, the researchers also note that participants who took antiplatelet drugs did not have a lower risk of dementia.  Like George Michael said in one of his songs: “You`ll never find peace of mind until you listen to your heart”. This is why additional efforts should be made to increase the use of blood thinners among older people with atrial fibrillation, in order to maintain good mental health.
COPYRIGHT: This article is the property of We Speak Science, a non-profit institution co-founded by Dr. Detina Zalli (Harvard University) and Dr. Argita Zalli (Imperial College London). The article is written by Harmela Sinanaj (University of Medicine, Tirana).
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