Stroke: Warning Signs and Risk Factors

Each year in the United States, there are more than 700,000 new strokes. Stroke is the third leading cause of death in the country, after heart disease and cancer. And stroke causes more serious long-term disabilities than any other disease. Nearly three-quarters of all strokes occur in people over the age of 65. And the risk of having a stroke more than doubles each decade after the age of 55.

What is a Stroke?

A stroke occurs when the blood supply to part of the brain is suddenly interrupted or when a blood vessel in the brain bursts, spilling blood into the spaces surrounding brain cells. Brain cells die when they no longer receive oxygen and nutrients from the blood or there is sudden bleeding into or around the brain.

Symptoms of a Stroke

  • Sudden numbness or weakness, especially on one side of the body
  • Sudden confusion or trouble speaking or understanding speech
  • Sudden trouble seeing in one or both eyes
  • Sudden trouble with walking, dizziness, or loss of balance or coordination
  • Sudden severe headache with no known cause.

Treatment can be more effective if given quickly. Every minute counts.

There are two forms of stroke: ischemic - blockage of a blood vessel supplying the brain, and hemorrhagic stroke - bleeding into or around the brain.

What is the Prognosis?

Although stroke is a disease of the brain, it can affect the entire body. A common disability that results from stroke is complete paralysis on one side of the body, called hemiplegia. A related disability that is not as debilitating as paralysis is one-sided weakness or hemiparesis. Stroke may cause problems with thinking, awareness, attention, learning, judgment, and memory. Stroke survivors often have problems understanding or forming speech. A stroke can lead to emotional problems.

Stroke patients may have difficulty controlling their emotions or may express inappropriate emotions. Many stroke patients experience depression. Stroke survivors may also have numbness or strange sensations. The pain is often worse in the hands and feet and is made worse by movement and temperature changes, especially cold temperatures.
Recurrent stroke is frequent; about 25 percent of people who recover from their first stroke will have another stroke within 5 years.

Stroke: An Attack on the Brain

A stroke is serious, just like a heart attack. A stroke is sometimes called a "brain attack." Most often, stroke occurs when blood flow to the brain stops because it is blocked by a clot. When this happens, the brain cells in the immediate area begin to die.
Some brain cells die because they stop getting the oxygen and nutrients they need to function. Other brain cells die because they are damaged by sudden bleeding into or around the brain. The brain cells that don't die immediately remain at risk for death. These cells can linger in a compromised or weakened state for several hours. With timely treatment, these cells can be saved.

New treatments are available that greatly reduce the damage caused by a stroke. But you need to arrive at the hospital as soon as possible after symptoms start to prevent disability. Knowing stroke symptoms, calling 911 immediately, and getting to a hospital as quickly as possible are critical.

Following a stroke, rehabilitation can greatly improve the survivor's quality of life.

Risk Factors for a Stroke

Stroke prevention is still the best medicine. The most important treatable conditions linked to stroke are:

  • High-Blood-Pressure. Treat it. Eat a balanced diet, maintain a healthy weight, and exercise to reduce blood pressure. Drugs are also available.
  • Cigarette smoking. Quit. Medical help is available to help quit.
  • Heart disease. Manage it. Your doctor can treat your heart disease and may prescribe medication to help prevent the formation of clots. If you are over 50, NINDS scientists believe you and your doctor should make a decision about aspirin therapy.
  • Diabetes . Control it. Treatment can delay complications that increase the risk of stroke.

What Research is Being Done?

The National Institute of Neurological Disorders and Stroke (NINDS) conducts stroke research and clinical trials at its laboratories and clinics at the National Institutes of Health (NIH), and through grants to major medical institutions across the country. Currently, NINDS researchers are studying the mechanisms of stroke risk factors and the process of brain damage that results from stroke. Basic research has also focused on the genetics of stroke and stroke risk factors. Scientists are working to develop new and better ways to help the brain repair itself to restore important functions. New advances in imaging and rehabilitation have shown that the brain can compensate for function lost as a result of stroke.


The National Institute of Neurological Disorders and Stroke (NINDS) conducts and supports research on brain and nervous system disorders.

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