Thursday, February 08, 2007

In study, bilingual brains stay sharp longer

In study, bilingual brains stay sharp longer
Benefits for older people may include greater ability to focus amid distractions.

By Carrie Peyton Dahlberg - Bee Staff Writer
Published 12:00 am PST Wednesday, February 7, 2007

After school, Carlos and Carmen Nguyen shuttle between two sets of grandparents in happy bursts of English, Spanish, Tagalog and Vietnamese.

Their parents love the way languages open their children's eyes to the family's heritage and to other cultures.

Yet when they began their multilingual journey, they never imagined that Carlos and Carmen, now 6 and 9, also might be developing brains especially good at ignoring distractions and better able to withstand aging.

"This is incredible," said the children's mother, Irene Bersola-Nguyen, a child development lecturer at California State University, Sacramento, who has been trading delighted e-mails with friends and colleagues about the latest study on the bilingual brain.

A team of Canadian researchers who studied people being treated for dementia found that those who regularly used two languages reported their first symptoms of a fading mind about four years later than those who used only one language.

That work, published in February's edition of the journal Neuropsychologia, follows a 2004 study that found older bilingual people were better at paying close attention despite distractions.

"Language pays off big time," said Ellen Bialystok, lead researcher on both studies and a scientist with the Baycrest Research Centre for Aging and the Brain in Toronto.

Bialystok and others cautioned that so many factors contribute to healthy aging, it would be premature to say language skills definitely delay dementia. Still, growing indications that bilingualism may deliver lifelong benefits in cognition have captured the attention of educators and researchers.

"Ellen Bialystok is a pioneer in this field, and she's generating quite a buzz," said Tamar Gollan, a University of California, San Diego, psychiatry professor who studies bilingualism. "People all over the world are replicating her findings for some of her earlier work."

Few places in the United States have more at stake in understanding the bilingual brain than California, where a staggering 42 percent of people age 5 and older speak a language other than English at home. In Sacramento County, it's 29 percent. With the immigrant population and the proportion of those who are fully bilingual both expected to grow, California could be a living laboratory for examining the impact of what we gain -- and lose -- from speaking more than one language.

There are clearly losses as well as gains, said Gollan, whose own research probes the subtle deficits of bilinguals. Yet when she weighed them, she came down soundly on the side of raising her own small children with two languages.

Bialystok, who began studying bilingual kids decades ago, believes one key to their special brainpower lies in the way they must constantly decide which language to use and which to suppress. For people who use two languages daily, "every time you want to speak one language, the other language is activated" in the brain as well, she said.

"That means you need a mechanism so that you're only drawing from the right pool (of words). It's going be a mechanism that works extremely fast ... while you're producing sentences. It's way below your radar for detecting what's happening."

So bilinguals get far more practice than monolinguals in using the part of the brain that focuses our attention, helping us sort through conflicting information and ignore distractions. Using two languages seems to bolster rapid decision-making, multi-tasking and perhaps memory.

To measure the effect in older adults, Bialystok used one of the many psychological tests designed to confound us, because we have to respond to information with conflicting cues. It may be a picture that requires you to move your left hand, which shows up on the right side of a computer screen. Or it may be the word "green," written in red letters. In such tests, bilingual people in their 70s did noticeably better than monolingual people. With lots of practice, the one-language speakers eventually caught up.

Fergus Craik, a senior scientist at Baycrest's Rotman Research Institute who collaborates with Bialystok, said ongoing research seems to point to memory advantages. Bilingualism may bolster the kind of memory that lets us recall specific things that happened to us or recognize a person out of context, Craik said.

Both researchers suspect that bilingualism may delay dementia in the same way that other intense mental activity is believed to, whether it's playing an instrument or solving puzzles.

Not everyone is convinced the "use it or lose it" strategy for maintaining a healthy brain has been proven, but it's something "we're all thinking about," said Dr. Charles DeCarli, a UC Davis neurology professor who heads the UCD Alzheimer's Disease Research Center.

"To the authors' credit, they're not saying that learning a language at age 50 is going to help you. In that regard, they're very cautious," DeCarli said.

While he wouldn't discourage anyone from studying a language, he recommends exercise, eating right and controlling blood pressure and cholesterol as surer bets for adults who want to delay dementia, based on what is known today.

DeCarli suspects further research may eventually trace the greatest brain-boosting advantages of bilingualism to childhood, between birth and ages 14 to 18, when crucial connections in the brain are being forged. When kids grow up speaking multiple languages, the same word juggling that helps them fend off distraction also exacts a price -- on vocabulary and on speed.

"For every single object or concept, if you're bilingual, you have two labels, and it takes additional time to learn twice as many words," UC San Diego researcher Gollan said. "It doesn't come for free."

Using their strongest language, bilingual people take just the tiniest bit longer -- about 8/100th of a second more -- to name an object when they're shown its picture, Gollan said.

When they're asked to rattle off lists, such as all the words you can think of in one minute that start with "S" or all the animals you can think of, they can't list as many. The difficulties that bilinguals have in their best language follow the same pattern as the difficulties that monolingual people with Alzheimer's have on such tests -- somewhat weaker with letter lists and more impaired with categories such as animals, Gollan said. Most of the effects are so slight a bilingual person would probably never notice, she said, but they're still important to understand.

"In the world, it's probable that bilinguals outnumber monolinguals," Gollan said, yet most of the research into language processing, cognitive skills and aging is done on monolingual subjects.

One cognitive problem that bilingual people might notice, Gollan added, is that they're likelier to struggle with that "tip of the tongue" sensation, when they know a word but for a fleeting moment can't produce it.

So far, that hasn't bothered Carlos and Carmen Nguyen of Sacramento, although both admit they fumble the most in Vietnamese. Their best language is English, their mother said, with Spanish a close second because they attend a dual-language immersion school.

The kids like the way languages let them reach out to cousins, grandparents and friends. And Carmen, who just took third place in a national essay contest about bilingualism, isn't ready to stop at four.

Next, she plans to learn French.

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