Atherosclerosis and brain damage: MRI insights

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  • Published: Dec 5, 2014
  • Channels: MRI Spectroscopy
thumbnail image: Atherosclerosis and brain damage: MRI insights

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MRI studies by researchers, including (from left) Drs. Christopher Maroules, Ronald Peshock, and Amit Khera, show that imaging can help predict the risk of cardiovascular events and vascular diseases in the brain.

A large-scale, US study involving magnetic resonance imaging (MRI) has demonstrated a link between a build up of fat and cholesterol in the arteries, atherosclerosis and cognitive impairment through deterioration of brain health. Fundamentally, the study found that people with thicker internal carotid artery wall, but otherwise a symptomatic, were up to 21 percent more likely to have cognitive impairment.

Christopher Maroules, a radiologist at the University of Texas Southwestern Medical Center in Dallas and colleagues studied almost 2000 adults, to investigate the buildup of fatty plaques in the body's major arteries. They present the results of their study at the annual meeting of the Radiological Society of North America (RSNA) in Chicago.

"It is well established that plaque build-up in the arteries is a predictor of heart disease, explains Maroules, "but the relationship between atherosclerosis and brain health is less clear." He adds that, "Our findings suggest that atherosclerosis not only affects the heart but also brain health."

Carotid correlation

Atherosclerosis is a common condition in which fatty substances, the waxy compound cholesterol and various other biochemicals accumulate on the interior wall of the arteries. They form plaques that can build up over many years, impeding the flow of blood to major organs and tissues as well as offering a risk of particles breaking off and entering the heart and causing additional problems, for instance. Atherosclerosis can occur in any artery of the body, including the carotid artery, which supplies blood to the brain, the coronary arteries and the aorta, which carries oxygenated blood from the heart through the abdomen to the rest of body.

The team analyzed test results from 1903 participants (with an average age of 44 years) all of whom were in the Dallas Heart Study, a multiethnic population-based study of adults from Dallas County, Texas. Crucially, the participants included both men and women who had no symptoms of cardiovascular disease. The team has the participants complete the Montreal Cognitive Assessment (MoCA), a thirty point standardized test for detecting mild cognitive impairment. They then gave them an MRI scan of the brain to identify white matter hyperintensity (WMH) volume. Bright white spots known as high signal intensity areas on a brain MRI indicate abnormal changes within the white matter.

"Increased white matter hyperintensity volume is part of the normal aging process," Maroules explains. "But excessive WMH volume is a marker for cognitive impairment." The team also carried out MRI scans to determine the build-up of plaque in the participant's arteries in two distinct vascular areas of the body: the carotid arteries and the abdominal aorta. Additionally, they used computed tomography (CT) to measure coronary artery calcium, or the amount of calcified plaque in the arteries of the heart.

A statistical regressional analysis was then used to detect any correlation between the incidence of atherosclerosis and mild cognitive impairment. The team adjusted for the well-known risk factors of atherosclerosis, including age, ethnicity, being male, diabetes, hypertension, smoking and body mass index (BMI), they found independent relationships between atherosclerosis in all three vascular areas of the body scanned with MRI or CT and cognitive health, as measured by participants' MoCA scores and white matter hyperintensity volume on the MRI.

Brain health

Individuals in the highest quartile of internal carotid wall thickness were 21 percent more likely to have cognitive impairment as measured by a low MoCA score. An increasing coronary artery calcium score was predictive of large white matter intensity volume on MRI. "These results underscore the importance of identifying atherosclerosis in its early stages, not just to help preserve heart function, but also to preserve cognition and brain health," Maroules suggests. The research suggests that MRI and CT imaging could offer patients invaluable prognostic information about their long-term cardiovascular and brain health risks.

"Plaque build-up in blood vessels throughout the body offers us a window into brain health," he adds. "Imaging with CT and MRI has an important role in identifying patients who are at a higher risk for cognitive impairment."

The study shows an association between the atherosclerosis and cognitive impairment but this does not necessarily prove cause and effect as there may well be many other confounding factors associated with both aspects. Indeed, the observed cognitive decline may be caused by another health factor that is also itself a risk factor for atherosclerosis in the first place. Inflammation caused by atherosclerosis may be one explanation for the cognitive impairment reported, recent unpublished date from the Dallas Heart Study having excluded impeded blood flow to the brain, Maroules told SpectroscopyNOW.

Related Links

Radiol Soc N Amer 2014, online: "Asymptomatic Atherosclerosis Linked to Cognitive Impairment"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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