"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.
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.
For the Bidens, the hospital vigil is a familiar scene. Biden's mother and infant sister died in a tragic car accident in 1972.
"One of my earliest memories was being in that hospital, my dad always at our side. We, my brother and I -- not the Senate, were all he cared about," Biden recalled at the 2008 convention in a speech that brought tears to Michelle Obama's eyes.
Six months ago, Biden was thought to be a shoo-in for the Senate seat his father held for 36 years. But he announced in January he would not run, telling ABC News in an interview, "I'm gonna, first things first, make sure I focus on my family."