News that vice president Joe Biden’s 41-year old son had a stroke may be surprising to many, but healthcare experts say that children and adults younger than age 45 account for 5 to 10 percent of all stroke cases.

"People don’t think that children and young adults can get strokes," said Loyola University’s Jose Biller, M.D. "Family members often are slow to recognize strokes."

Biller, who wrote a textbook titled "Stroke in Children and Young Adults," says that stroke risk increases dramatically with advancing age. The incidence of stroke doubles each decade past 55 years of age and half of all strokes occur in people older than 70 to 75 years.

A large proportion of strokes are preventable by controlling blood pressure, treating irregular heart rhythms and stopping cigarette smoking.

Warning signs of a stroke include sudden weakness of the face, arm or leg, especially on one side of the body, numbness or tingling of the face or one side of the body, confusion or trouble understanding, trouble speaking, trouble seeing in one or both eyes, trouble walking, dizziness, loss of balance or coordination and severe, unusual headaches.