Dear Doctor: A relative long ago diagnosed with atrial fibrillation has been behaving differently, such as sitting with his mouth gaping open, not attending to financial matters, taking too long to do errands, that kind of thing. Could silent TIAs be the culprit?
Dear Reader: Yes, they could. First, let's explain atrial fibrillation. Two chambers known as atria make up the top portion of the heart, storing blood before it goes into the two bottom chambers, known as ventricles. The atria contract first, then the ventricles, setting the overall rhythm of the heart. In atrial fibrillation, the atria are damaged or enlarged and don't contract sufficiently or rhythmically. Because of this, some blood can stay within them, leading to a clotting of blood in this portion of the heart.
If the atria contract normally or the clot mobilizes for some other reason, then the clot can move into the ventricles, where it can then shoot into the circulatory system when the ventricles contract. The clot can then become lodged in the smaller blood vessels of the brain, leading to lack of blood flow to that area. The result is either a transient ischemic attack (TIA), in which a portion of the brain loses function for a short period, or a full-fledged stroke.
Atrial fibrillation could indeed be leading to small strokes in your relative. Often, these small strokes are not noted by the patient or by family members. A study in elderly residents in Germany found that 12.7 percent of them had experienced what's known as "silent strokes." Such strokes don't have obvious symptoms; instead, they can manifest as a difficulty in performing cognitive tasks or a slowing in everyday activities. Your relative's risk of strokes linked to atrial fibrillation would be lower if he has been taking blood thinners, but they still could occur.
A CT scan or MRI can easily determine whether your relative has had these silent strokes. It's important to get such a diagnosis because if his symptoms are related to a small stroke, he'll be at greater risk of having a large, debilitating stroke.
His symptoms could be linked to another type of stroke as well -- a lacunar stroke caused by very high blood pressure and diabetes, which lead to a narrowing of smaller blood vessels in the brain. These strokes can cause loss of function in a limb or the problems traditionally found in silent strokes.
Whether caused by atrial fibrillation or a narrowing of blood vessels, multiple strokes can lead to dementia, which also may be the reason for your relative's recent behavior. Alzheimer's disease, Lewy body dementia and normal pressure hydrocephalus also can cause the symptoms you describe, and imaging of the brain and a consultation with a neurologist can confirm these diagnoses.
Let's not forget another cause: depression. Depression in the elderly can have many of the same symptoms as dementia, causing difficulty in focusing on tasks, memory and self-care. Lastly, if the symptoms in your relative developed suddenly, infection could be the culprit.
In short, your relative's symptoms have many possible causes. But you're astute in thinking that TIAs or silent strokes due to atrial fibrillation may be to blame. Please encourage him and his closest family member to see a doctor; he obviously needs medical attention and recommendations specific to his needs.
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