Nearly 800,000 people experience a stroke each year, according to the National Stroke Association.
Luke Perry became one of those people when he suffered a stroke Wednesday and was rushed to a California hospital, where the "Riverdale" actor remains sedated.
It's a reminder of the seriousness of this medical emergency. So what exactly is a stroke? The NSA describes it as a "brain attack." There are two types of strokes: When a brain aneurysm bursts or a weakened blood vessel leaks, and when a blood clot blocks blood flow to the brain. This deprives brain cells of oxygen and kills them.
"For each minute a stroke goes untreated and blood flow to the brain continues to be blocked, a person loses about 1.9 million neurons. This could mean that a person’s speech, movement, memory, and so much more can be affected," the NSA says on its website.
How can you tell if someone is having a stroke, and how can you help? You must act "FAST," according to the NSA.
Face: Does one side of their face droop when they smile?
Arms: Does one arm drift downward or appear weak when they raise both arms?
Speech: Does their speech sound slurred or strange when they say a simple phrase?
Time: Call 911 immediately if a person exhibits any of these signs.
Other symptoms of a stroke include: sudden numbness on one side of the body, sudden confusion or trouble speaking and understanding, sudden trouble seeing, sudden dizziness or loss of balance, and a sudden headache with no known cause.
The NSA says it is important to note the time the first symptom is observed. That time frame can affect treatment by medical professionals.
To help prevent a stroke, the NSA says people should have healthy eating habits, exercise and avoid smoking. High blood pressure, atrial fibrillation, high cholesterol, diabetes and circulation problems are also risk factors for a stroke.