Does the Altered Blood Flow of Atrial Fibrillation Contribute to Dementia?

Given what we know of the relationship between hypertension and dementia, in which increased blood pressure damages the fragile tissues of the brain, causing loss of function over time, it is reasonable to consider that other disruptions of blood flow could have a similar relationship with the onset of dementia in later life. Researchers here investigate the association between atrial fibrillation and dementia, in search of specific disruptions in blood flow and brain tissue that could explain this relationship in terms of greater structural damage to the brain.

Researchers enrolled 246 patients in the study: 198 with atrial fibrillation and 48 without atrial fibrillation. They then obtained plasma samples and tested them for the circulating levels of four biomarkers associated with brain injury: glial specific GFAP and S100b; GDF15, a stress response marker; and neuron-specific tau protein. They found that levels of three of those biomarkers - tau, GDF15, and GFAP - were significantly higher in patients with atrial fibrillation. "We think patients with atrial fibrillation experience chronic, subclinical cerebral injuries. It becomes absolutely critical to identify the early markers of this injury and help these patients who are at higher risk of having subsequent neurodegenerative problems, such as cognitive decline and dementia."

Atrial fibrillation is an irregular and sometimes rapid heartbeat that can lead to blood clots, stroke, heart failure, and other heart-related problems. If people with atrial fibrillation are indeed suffering from ongoing brain injuries, they can also be at higher risk of developing everything from depression to neurodegeneration, which is the deterioration or death of the body's nerve cells, especially neurons in the brain, which could cause losses in mental function. That could be because 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, which filters blood to and from the brain and spinal cord. If it's not working correctly, neuro-specific molecules like GFAP and tau get into the bloodstream, which was seen in this study.

The next step is to carry out the same kind of analysis on a larger group of patients. Recent results from the Swiss Atrial Fibrillation Cohort Study also point in the same direction - that atrial fibrillation causes brain injury. In the study, researchers performed MRIs on atrial fibrillation patients and found that 41 percent showed signs of at least one kind of a silent brain damage.

Link: https://www.eurekalert.org/pub_releases/2018-11/imc-rff110618.php

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