NEW YORK (Reuters) - Less than one in five people can recognize the signs of stroke and know what to do when one occurs, new research reports.

New treatments for stroke exist, but they must be administered within a few hours after symptoms begin, study author Dr. Kurt J. Greenlund told Reuters Health.

Consequently, knowing the signs of stroke and getting immediate help can make the difference between life and death, he noted.

"Calling 911 as soon as possible when people think someone is having a stroke is very important," Greenlund said.

The most common type of stroke occurs when a clot or blocked artery cuts off blood flowing to the brain. People experiencing this type of stroke do much better if treated with a clot-busting drug within a three-hour window after symptoms begin.

The major warning signs for stroke are a sudden weakness or numbness, sudden slurred speech, disorientation, and a difficulty understanding.

According to the American Stroke Association, stroke is the third leading cause of death in the United States, after heart disease and cancer. However, previous research has shown that many Americans do not know what stroke symptoms look like.