How the Brain Functions

Stroke is a form of cardiovascular disease affecting the blood supply to the brain. Also referred to as cerebrovascular disease or apoplexy, strokes actually represent a group of diseases that affect about one out of five people in the United States. When physicians speak of stroke, they generally mean there has been a disturbance in brain function, often permanent, caused by either a blockage or a rupture in a vessel supplying blood to the brain. In order to function properly, nerve cells within the brain must have a continuous supply of blood, oxygen, and glucose (blood sugar). If this supply is impaired, parts of the brain may stop functioning temporarily. If the impairment is severe, or lasts long enough, brain cells die and permanent damage follows. Because the movement and functioning of various parts of the body are controlled by these cells, they are affected also. The symptoms experienced by the patient will depend on which part of the brain is affected. Stroke is a major health problem in this country. Nearly 500,000 people in the United States have a stroke each year, and nearly a third of these people die during the first few months after their stroke, Of those who survive, about 10 percent are able to return to their previous level of activity, about 50 percent regain enough function to return home and carry on with only limited assistance, and about 40 percent remain institutionalized or require significant assistance in caring for themselves. While the incidence of stroke has decreased a great deal over the past few decades, there is evidence that this trend may be leveling off. Stroke is costly. The cost in human terms, to patients and their families, is impossible to estimate. The cost to the U.S. economy—in terms of medical care and lost income—amounts to over $25 billion each year. Although stroke is often viewed as a disease of the elderly, it sometimes affects younger individuals. The incidence of stroke does increase with age, but nearly a quarter of all strokes occur in people under the age of 60. Stroke patients are often cared for by neurologists, because of the complex nature of the symptoms caused by damage to the brain. However, strokes are very closely related to heart disease. Heart attacks (myocardial infarctions) and stroke are both caused by diseases of the blood vessels. They share many of the same risk factors, and modifying these risk factors may reduce the possibility of stroke. Many of the therapies used for cardiac disease show promise for some types of stroke. Finally, people who already have coronary disease may be at greater risk for stroke, and vice versa.