A stroke occurs when the blood flow to the brain is interrupted (ischemic stroke) or a blood vessel in the brain bursts (hemorrhagic stroke). In either of these cases, brain cells begin to die because blood can't reach them and they can't get the oxygen and nutrients they need to function.

The other type of stroke is hemorrhagic and is caused when a blood vessel in the brain bursts and causes bleeding in the brain. About 20 percent of strokes are of this type, according to the NINDS.

The symptoms of stroke occur suddenly and quickly. The numbness or weakness can also occur in the face; the weakness or numbness also may occur on one side of the body. A person having a stroke may suddenly have difficulty speaking or understanding what someone is saying to them. The person may suddenly have trouble walking and lose his or her balance; sudden dizziness is another symptom. If you are with someone who is experiencing any of these symptoms, seek medical help immediately.

Without counting any other risk factors, smoking almost doubles a younger adult's risk for ischemic stroke, according to the NINDS. Heavy smokers are at greater risk than people who don't smoke as much. In older adults, although smoking can be a contributing cause, high blood pressure, heart disease and diabetes are stronger factors. Heart disease, however, can be caused by smoking.

About a third of Americans, or 65 million people, have high blood pressure (a reading of 140/90 or greater or using medication to control blood pressure), and up to 90 percent of people who have a stroke had high blood pressure before their stroke occurred, according to the NINDS. That's why it's important to have your blood pressure checked regularly, and if it is high, follow your doctor's recommendations on lowering it. Blood pressure medication can decrease a person's risk for stroke by about 40 percent. High cholesterol and diabetes are other risk factors for stroke that can be controlled. Factors for stroke that can't be changed include increasing age, gender, race or ethnicity and family history.

Ischemic strokes are treated with a medication called t-PA, which dissolves blood clots blocking blood flow to the brain, according to the NINDS. To work effectively, the drug must be given within 3 hours of the onset of stroke symptoms. Because a person suspected of having a stroke must be evaluated first by hospital staff, the NINDS says that the person must arrive at the hospital within an hour of the onset of symptoms. According to the American Stroke Association, only about 3 to 5 percent of people who suffer a stroke reach the hospital in time for this treatment.

Antiplatelet and anticoagulant medications are given to help prevent a stroke. Antiplatelet medication prevents the blood from clotting by affecting how the platelets do their job, according to the NINDS. Reducing the risk for blood clots cuts the risk for ischemic stroke. Aspirin is the most commonly used antiplatelet medication, although others such as clopidogrel and ticlopidine are available. Anticoagulants also reduce the ability of the blood to clot. Warfarin and heparin are two common anticoagulant medications. Thrombolytic (clot-busting) medication is given to a person having an ischemic stroke, or within three hours of the onset of stroke symptoms, to help prevent damage.

Most stroke patients need some form of physical and occupational therapy. A person who has had a stroke may need help relearning basic skills such as how to walk, sit, stand or lie down, according to the NINDS. The person may also need help with eating, drinking, dressing, bathing, cooking and using the toilet.