Imaging Reveals Calcified Plaque in Arteries May Pose Dementia, Stroke Risk

Greater calcium build-up in the blood vessels outside the brain may be associated with brain changes associated with the future risk of dementia and stroke, according to new research.

The study’s findings were published online August 25, 2011, in the journal Arteriosclerosis, Thrombosis and Vascular Biology. “The relationship between calcium in atherosclerotic plaque and brain changes exists on top of the effect of classic cardiovascular risk factors such as high blood pressure, smoking, and diabetes,” said Meike W. Vernooij, MD, PhD, senior study author and assistant professor of epidemiology and radiology at the Erasmus Medical Center (Rotterdam, The Netherlands).

Furthermore, the amount of hardened, calcified plaque provided more data about the extent of brain changes than conventional ultrasound measures of the presence of plaque in the carotid artery.

The researchers assessed 885 people, average age 67, participating in the Rotterdam Study, which includes varying types of imaging to understand better the causes and predictors of dementia and stroke. They utilized computed tomography (CT) scans to measure calcification in four blood vessel areas: the coronary arteries that feed the heart; the aortic arch; and the extracranial and intracranial carotid arteries that carry blood through the neck into the brain.

Researchers used magnetic resonance imaging (MRI) of the brain to visualize small brain infarctions, microbleeds, and bright areas called white matter lesions. White matter in the brain is comprised of the fiber tracts that carry data to and from the brain. White matter lesions are more typically seen in patients who have risk factors such as a history of hypertension, diabetes, and high cholesterol. “These subclinical brain changes, apparent on MRI, do not necessarily cause symptoms right away but are frequently seen in patients with stroke or dementia and over the long term may be associated with worse cognitive performance,” Dr. Vernooij said.

Among the study’s findings were (1) that calcium build-up in each of the four arteries scanned was associated with the presence of small brain infarctions and white matter lesions in the brain. (2) No associations were found between microbleeds in the brain and calcification in any of the arteries studied. (3) As predicted, the amount of calcification in vessels closer to the brain--the extracranial and intracranial carotids--had the strongest relationship to MRI markers of vascular brain disease. (4) Lastly, the most prominent associations were found between intracranial carotid calcification and the volume of white matter lesions, and extracranial carotid calcification and brain infarctions.

“The distinction between the impact of calcification in the extracranial and intracranial carotids adds to the current belief that white matter lesions mainly result from disease in smaller intracranial vessels, while brain infarctions are thought to be mainly caused by larger vessel disease,” Dr. Vernooij noted.

The results will be used to further the understanding of how atherosclerosis affects brain function and ultimately the risk of developing dementia and stroke. “We are a long way from using CT-assessed calcification to screen individuals for brain lesions and dementia risk,” Dr. Vernooij said.

Unanswered questions include whether treatment can reduce calcification in blood vessels and whether doing so would improve cognitive health or lower the risk of dementia and stroke. However, if a physician has performed a heart CT scan to evaluate heart attack risk, the findings may provide information that extends beyond the reason for the examination. “Though far away from the brain, calcification in coronary arteries may indicate the presence of subclinical brain disease as well,” Dr. Vernooij stated.

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Erasmus Medical Center