From Associated Press:

WASHINGTON — Mastering a second language can pump up the brain in ways that seem to delay getting Alzheimer's disease later on, scientists said Friday.

While the new research focuses mostly on the truly long-term bilingual, scientists say even people who tackle a new language later in life stand to gain.

The more proficient the person becomes, the better, but "every little bit helps," said Ellen Bialystok, a psychology professor at York University in Toronto.

Much of the study of bilingualism has centered on babies, as scientists wondered why simply speaking to infants in two languages allows them to learn both in the time it takes most babies to learn one. Their brains seem to become more flexible, better able to multitask. As they grow up, their brains show better "executive control," a system key to higher functioning — as Bialystok puts it, "the most important part of your mind."

Speaking two languages may delay Alzheimer's - Health - Alzheimer's Disease - msnbc.com