Alzheimer's self-defense: Are two languages better than one?

(CBS/AP) - Two languages may be better than one when it comes to protecting your brain from Alzheimer's disease, recent research suggests.

The research focuses mostly on people who are truly bilingual and have been for many years, but scientists say learning a new language later in life might help.

Ellen Bialystok, a psychologist at York University in Toronto, studied 450 people with Alzheimer's. Those who were bilingual were diagnosed between four and five years later than those who spoke only one language. She discussed her research Friday at a science meeting in Washington.

More than five million Americans have Alzheimer's disease, according to the Alzheimer's Association. The disease is the fifth-leading cause of death.