In a study of nearly 2,000 adults, researchers found that a buildup of plaque in the body's major arteries was associated with mild cognitive impairment. Atherosclerosis is a condition in which fat, cholesterol and other substances collect in the arteries, forming a substance called plaque that can build up, limiting blood flow. It can occur in any artery of the body, including the carotid, which supplies blood to the brain, coronary arteries and the aorta, which carries oxygenated blood from the heart through the abdomen to the rest of body.