Biden is being treated by Dr. Timothy Gardner, medical director of the Center for Heart and Vascular Surgery at Christiana Care Health System, who said he likely will have a full recovery.
Biden has what the doctors "believe to be a mild stroke," according to Gardner. "[He is] "fully alert, in stable condition and has full motor and speech skills."
Hospital officials said Biden was communicating with his wife and parents, who were with him. He is being transferred today to Thomas Jefferson University Hospital in Philadelphia for "further observation and examination," according to the vice president's office.
Young adults under 45, like Biden, are not immune to stroke, the third leading cause of death in the United States, behind heart disease and cancer.
An estimated 10 to 15 percent of strokes -- most of them ischemic or due to blood clots, rather than hemorrhaging -- occur in those under 45, according to Dr. Aneesh Singhal, associate professor of neurology at Harvard Medical School, who practices at Massachusetts General Hospital in Boston.
Young men over the age of 30 are more prone to strokes than women, who are more vulnerable under 30. African Americans are also more likely to suffer a stroke at a young age.
Biden, 41, was elected as Delaware's attorney general in 2006. He recently served in Iraq for one year as a captain with the Delaware Army National Guard. He was considered a front-runner to fill his father's former U.S. Senate seat this November, but in January he announced he had decided against a run for higher office.
More 700,000 Americans, some of them young and seemingly healthy, have a stroke each year; women have about 55,000 more than men.
Because less is known about this disease among young people, the American Academy of Neurology has just received a grant to study stroke in that population, according to Singhal.
"The risk is still very low, but young men and women need to be aware," said Singhal. "Stroke is the leading cause of disability worldwide. It can happen in the young, and one of the real problems is they don't recognize the symptoms and it is often overlooked in the emergency department when they visit."
Just last year, a Wayne State University study revealed that young adults arriving in hospital emergency rooms after a stroke are often misdiagnosed.
Researchers found eight of 57 stroke patients were incorrectly diagnosed with conditions including vertigo, migraine, alcohol intoxication, seizure, an inner ear disorder or other conditions.
Stroke kills about 137,000 Americans a year, according to the Centers for Disease Control and Prevention. It is also the leading cause of disability.
About 6,400,000 stroke survivors are alive today; 2,500,000 are males and 3,900,000 are females, according to the 2010 American Stroke Month newsroom.
Studies show that about 795,000 people suffer a new or recurrent stroke each year. About 610,000 of these are first attacks and 185,000 are recurrent attacks. Women account for 60 percent of stroke deaths.
A stroke, sometimes called a brain attack, occurs when a clot blocks the blood supply to the brain (ischemic stroke) or when a blood vessel in the brain bursts (hemorrhagic stroke).
It can cause disabilities such as paralysis, speech and, especially among young people, emotional problems.
The first hours are critical in treatment. In the case of an ischemic stroke, the most common among the young, doctors can administer the clot-busting drug tissue plasminogen activator, or tPA, the only U.S. government-approved treatment for acute stroke. It must be given within three hours of the onset of symptoms to reduce permanent disability.
"Recovery rates in the young are much better than when you are older, but up to half of all patients still have symptoms and a third are unable to return to work," said Singhal. "The psychological impact, the social and emotional changes after stroke are much bigger in the younger population."
Risk factors for ischemic stroke in young adults include a personal and familial history of migraines, smoking and, in women, oral contraceptives.
Women who have all three risk factors have a 16 times greater chance of having a stroke, according to Singhal. There have been some associations between stroke and preeclampsia in pregnancy.
In younger people, stroke can be related to cardiac and blood vessel abnormalities, substance abuse, contraception or even lupus. Drugs, such as cocaine, ecstasy, amphetamines and other drugs that cause arterial narrowing can precipitate stroke.
Arterial dissection -- when arteries tear due to a minor trauma -- can also be a cause.
"If you stretch your neck in an awkward position or have a contact injury in racquetball or tennis or fall and hit your head, a little tear in the artery can be a source of clot formation," he said.
Another common cause in both males and females is a congenital hole in the heart.
Such was the case with Dina Pagnotta, whose heart defect was only discovered when she suffered a stroke at age 30. Today, she has been symptom-free for eight years and has since run three marathons.
Pagnotta, a physical therapist, was waiting for a group pilates class when she began to feel "odd." Thinking her blood pressure had dropped or she was dehydrated, she went for sip of water but then realized she couldn't even swallow.
"I was spitting the water out, and my friend looked at me and said I had a strange look on my face," said Pagnotta, who is now 38. "I felt as if I had been injected with a shot of novocaine, like I was sinking into my left side and my speech was slurred."
The paramedics were called but when she arrived in the emergency room, doctors were initially baffled.
"They were poking and prodding and asked if I had done drugs or been on a recent flight," she said. "No one expects a 30-year-old to have a stroke."
"I was terrified," said Pagnotta, who has now fully recovered and works with young stroke survivors. "Strokes don't discriminate."
Leean Hendrix, a Miss America pageant contestant who suffered a stroke at the age of 26, was not so lucky.
Stroke hit when she was living in Phoenix, winding down her reign as Miss Arizona.
"I was at home doing the laundry, feeling fine," she said. "It didn't hurt -- it felt like the muscles behind my eyes broke, kind of like my eyes were doing loop-de-loops. I thought maybe I hadn't eaten well enough. But I closed my eyes and it got worse."
When a friend helped Hendrix to clumsily make her way to the bathroom mirror, bumping into furniture along the way, she could see the right side of her face was "droopy."
Soon, she had no control over her eyes at all. "Oh my God," she thought to herself. "I am having a stroke."
By the time Hendrix arrived at the critical care center, her whole right side was not responding and aphasia - or the inability to communicate -- set in.
She tried to talk, but only "gibberish" came out. "The brain literally forgets how to talk," she said.
Hendrix was unconscious for six hours and doctors had no idea what was wrong with her. "When I arrived at the emergency room doctors left me on the gurney for hours unattended while the stroke ravaged my brain," said Hendrix.
When she was eventually diagnosed, doctors learned she had a congenital hole in her heart that had caused the stroke. Only days before, Hendrix had sprained her ankle and not followed doctors' advice to stay off her feet.
A clot broke free, shot through her heart and into the vessels of her brain.
Today, at 34, Hendrix still struggles with severe memory loss and partial paralysis.
"I had just completed the pageant and yet I couldn't brush my own hair," she said of the ordeal.
Hendrix had to return to college to relearn basic math and could no longer sustain her high-pressure job. Today she works as a dental assistant.
"I forced myself with the help of others to get things back, but nothing is really the same as it was," she said.
Hendrix also travels around the country and shares her story, lobbying for bills and helping other stroke survivors.
"It has turned into amazing friendships," she said. "It opened my eyes and I kind of feel blessed. I found out what was important at such a young age. I used to think I wanted to come home to a closet full of nice clothes or a new car, but all that can be stripped from you."
The National Stroke Association recommends the F.A.S.T. test as a quick screening tool to identify strokes:
Face -- Ask the person to smile. Does one side of the face droop?
Arms -- Ask the person to raise both arms. Does one arm drift downward?
Speech -- - Ask the person to repeat a simple sentence. Are the words slurred? Can they repeat the sentence correctly?
Time -- If the person shows any of these symptoms, time Is important. Call 911 or Get to the hospital. Brain cells Are dying.