Even learning a second language later in life delays the decline important brain functions, Ellen Bialystok of York University in Toronto, Canada, told reporters at the annual meeting of the American Association for the Advancement of Science currently meeting in Washington DC.

She said that a set of cognitive processes known as the 'executive control system' - which allows us to think in complex ways and controls the allocation of attention - is enhanced in people who are actively bilingual throughout their lives.

Bialystok's group identified this enhancement in the brains of children, adults and older people, the latter being when this system begins a natural decline.

450 sufferers studied

Bialystok's group studied 450 sufferers of Alzheimer's disease: half of them were bilingual, and the other half spoke only one language.

Researchers know that the disease attacks the median temporal area of the brain at the steady predictable rate.

Yet, despite all of the patients being selected for the same level of impairment, those who spoke two languages were, on average, diagnosed with Alzheimer's 4.3 years later and reported the onset of symptoms 5.1 years later than patients who were monolingual.

"Which means they've been able to cope with the disease [for longer]," Bialystok said, adding that being bilingual "is protecting older adults, even after Alzheimer's disease is beginning to affect cognitive functioning. Bilinguals can continue to function, even though there's damaged brain tissue."

Cognitive decline is slower

Another study, as yet published, used computed tomography scans to show that bilinguals had the same level of cognitive decline as monolinguals, even when the people who spoke multiple languages were at a more advanced stage of Alzheimer's, Bialystok said.

"One of the reasons bilingualism has these powerful mechanisms - including protecting against early symptoms of dementia - is because it's one way to keep your brain active," she told reporters.

Never too late to learn

"Every little bit helps. The longer you've been bilingual, the more you use all your languages, the more fluent you are, all of those things contribute," she added.

"Even if you're starting to learn a language at 40, 50, or 60, you're unlikely to become bilingual, but you are keeping your brain active. So you're contributing to 'cognitive reserve' through very engaging and intense activity."

Cognitive reserve is the brain's ability to utilise various brain networks to optimise its performance. "Bilingualism is a cognitively demanding," she said, and this "contributes to cognitive reserve in much the same way as do other stimulating intellectual and social activities," she said.

shutting out distractions

Other studies found that bilingual speakers are better than monolinguals at shutting out distractions and focusing on what's important, which makes them much better at multitasking, said Amy Weinberg of the University of Maryland.

"Getting to some level of proficiency in a second language certainly makes you an expert multitasker," added Weinberg, a professor of linguistics.

"When you're speaking, all the languages you speak are turned on, and you have to activate a mechanism in the brain that allows you to limit interference from one language when talking in the other," she said.
"You're juggling all kinds of mental balls as a bilingual," she said.

This mental juggling act is what makes people who speak more than one language more adept at managing several tasks at once, agreed Judith Kroll, director of the centre for language studies at Penn State University.

"The bilingual is somehow able to negotiate between the competition of the languages, and the speculation is that these cognitive skills come from this juggling of languages," she said.

But an ability to speak two or three languages does not make someone more intelligent. "Bilinguals simply acquire specific types of expertise that help them attend to critical tasks and ignore irrelevant information," added Kroll.