The most important factor to keep in mind during a stroke is not wasting time, say neurological specialists. “Time is brain,” is the common medical adage, because every second counts to get the best possible outcome.

According to Army Lt. Col. (Dr.) Michael Crimmins, chief of interventional neuroradiology and stroke medical director at the Walter Reed National Military Medical Center in Bethesda, Maryland, humans lose about 1 million brain cells per minute during a stroke. He recommends getting to a hospital right away, preferably by ambulance, “because they can bypass triage and get you immediate medical attention.”

A stroke can cause lasting brain damage, long-term disability, or even death, says the Centers for Disease Control and Prevention. Crimmins explained strokes are the No. 1 leading cause of preventable disability in the United States and among the top 10 causes of death for men and women in the country.

They can occur from two scenarios:

“There are ischemic strokes, where a blood clot stops the blood from flowing into the blood vessels of the brain,” said Crimmins. “And there are hemorrhagic – or bleeding – strokes, where a blood vessel tears or ruptures, causing bleeding into the brain.”

In both cases, the flow of oxygen and nutrients to the brain is interrupted.

“When you lack blood flow to the brain for long enough, the neurons – the brain cells – start to die,” said Crimmins. “The brain and the neurons control our ability to use our bodies, so once they die it’s very difficult to recover that function, especially as we get older.”

These include functions like movement, breathing, and digestion; memory storage; and thoughts, emotions, and language, according to the CDC.

Ischemic strokes, noted Crimmins, are what most people think about when they think about stroke. Those can be caused by a variety of factors.

“The most common cause is frequently due to an embolism, a clot that forms in the heart, which the heart then pumps into the brain,” he said. “Other people have carotid artery disease and others have narrowing, or atherosclerosis, of the blood vessels of the brain itself, so any one of those can stop blood from flowing into the brain.”

And while there are risk factors that elevate the potential for suffering a stroke, having one often happens out of the blue, with patients not realizing they’re having a stroke “until they do,” he said.

“In that case, the onset of symptoms is very quick – they go from having no symptoms one minute to having an inability to speak or move a part of their body the next.”

Risk factors can be genetic and include hypertension, diabetes, elevated cholesterol, smoking, and the use of illegal drugs, such as cocaine. But, according to Crimmins, they’re treatable.

“Sometimes, we can work on those with medication, by adjusting the patient’s diet, or helping them make other lifestyle changes to reduce inflammation,” he said. “If you have concerns over some other risk factors, it would be smart to try and maximize your health, like getting these medical conditions under control to prevent strokes and the potential for dementia down the road.”

At a military medical treatment facility, neurologists like Crimmins conduct a series of tests to identify the type of stroke a patient is having before treating it.

“We can potentially give clot-busting medication or even do a surgical removal of a clot by accessing the artery in the leg and going up to do an extraction,” he said.

The medication works by dissolving the clot and improving the blood flow to the part of the brain being deprived of blood and oxygen, noted Crimmins.

“For severe strokes, surgical intervention has been found to be the most helpful way to treat somebody with a severe stroke,” he said.

Either way, the most important takeaway is getting immediate attention. “We know that the longer you wait the less likely you are to have a good outcome after a stroke,” said Crimmins.

Below are some important facts about strokes:

1. Don’t waste time – act F.A.S.T. to get medical attention as soon as you notice symptoms of a stroke.
2. Men and women present the same symptoms of strokes.
3. Depending on which blood vessel is closed off, symptoms can include any change in typical brain function: Slurred speech or a change in speech, such as a “word salad” in which words don’t seem like they go together and are not what a person means; weakness on the arm, face, or leg; double or blurry vision; severe vertigo or dizziness, severe headache.
4. It’s possible to have a stroke and not even know it: Strokes can be asymptomatic, or silent, and are only discovered as scar tissue on the brain once people see their doctor for what they think are memory problems or headaches.
5. Untreated strokes can lead to dementia due to a chronic loss in mental faculties.
6. You can help reduce your risk of stroke by maintaining healthy living habits and controlling certain medical conditions.
7. Once you have a stroke, you’re at higher risk of having another stroke soon.
8. Strokes occur more frequently in the people between the ages of 60-80. However, there are a fair number of younger people who have strokes, including service members, due to irregular heart rhythm or a tear in the blood vessels, called a dissection.