One of the reasons Alzheimer’s disease is so terrifying is that scientists have yet to pinpoint exactly why some people get the disease and others do not. Yet as they delve deeper into the causes of both heart disease and Alzheimer’s, researchers are turning up evidence of common symptoms.
For instance, two decades ago a Kentucky medical examiner noted that the brains of people who had died from heart disease were more likely to have “plaques and tangles” characteristic of Alzheimer’s disease. (“Plaques” refer to abnormal clumps of amyloid protein that occur between nerve cells; “tangles” are an accumulation of a different protein, called tau protein, inside of nerve cells.)
But why is this so? One of the major suspects appears to be atherosclerosis (hardening of the arteries), the disease process that causes coronary artery disease. Atherosclerosis is the buildup of the fatty plaque, which narrows the heart’s coronary arteries, impeding its ability to pump blood to the rest of the body, including the brain.
And the brain is a glutton for blood; in fact, it uses 20 to 25 percent of the blood the heart pumps. Therefore, any reduction in blood flow damages the brain, and can pave the way for Alzheimer’s disease.
Studies have found that this shortage of oxygen activates a gene that is responsible for producing the harmful amyloid-beta plaques found in the brains of Alzheimer’s patients. This process sets off a cascade of chemicals that kill brain cells and cause Alzheimer’s disease.
Because of this process, scientists are increasingly viewing Alzheimer’s as a vascular disease, similar to coronary artery disease or stroke.
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