The imaging showed different patterns of activity in the frontal part of the brain, in an area used for processing such tasks.

Brian Gold is a neuroscientist at the University of Kentucky College of Medicine. He was also the lead author of the study.

“We found that seniors who are bilingual are able to activate their brain with a magnitude closer to young subjects. So they don’t need to expend as much effort, and yet they still out-perform their monolingual peers, suggesting they use their brain more efficiently.”

He says that knowing a second language made no difference for the young adults. They did better at the exercises than both groups of older people. But he says the older bilingual adults appear to have built up a kind of surplus from a lifetime of increased mental activity.

He says his findings confirm an earlier study on bilingualism among patients with Alzheimer's disease. That study showed that bilingual speakers developed more damage, but were able to think at the same level as patients with less damage.

Dr. Gold says he believes the new study confirms that bilingualism can play a protective role in the brain. He now plans to study whether learning a second language or immigrating to another country as an adult can provide some of the same mental advantages as lifelong bilingualism.

The study appeared in the Journal of Neuroscience.