In a recent study at the University of Manchester in the UK, researchers found that participants with Alzheimer’s and vascular dementia had significantly more blood clots in their brains than those with no dementia. The scientists used ultrasound testing to look for clots in the brains of 320 people.
These clots, or emboli, are formed outside the brain, then travel to the brain through the bloodstream. Once the clot is in the brain, it blocks the blood flow cells need to function. The researchers explain that a large clot can cause a stroke, but many small clots over the years may cause brain damage and dementia, without any symptoms of stroke. The clots are often caused by problems with heart rhythms or by carotid artery disease. The carotid arteries are the large arteries running up through the neck to bring blood to the head.
The study is interesting because if further research confirms this association between clots and dementia, testing for clots could be used to identify people at risk for dementia. If these clots actually are found to cause dementia or Alzheimer’s, it might be possible to treat patients with medicines that keep clots from forming.
We don’t know if my father had the cerebral emboli found in this study – this type of ultrasound testing is not typically performed on patients. His medical records say that his carotid arteries were clear. But what about problems with his heart?
“All of our dementia patients get heart checks,” says Dad’s last neurologist, Dr. Frank Fleming of East Carolina Neurology, “but not necessarily rhythm monitoring for extended times.” But Dad was monitored for 24 hours to check for this type of heart problem, and although his heart beat was slow, there were no major problems with the rhythm.
Dr. Fleming notes that it isn’t clear yet what the advantage would be of monitoring the heart function of every dementia patient for these extended periods. In this new study, in fact, 40% of the dementia patients with these clots showed no signs of heart or carotid artery problems. The researchers hypothesized that dementia and clots might have a common cause, rather than a cause and effect relationship.
We’ll have to wait to see if further research confirms this association between clots and dementia, and then try to understand what the relationship means for screening or treatment.