A bilingual brain is prepped for more than a second language | Science News

A bilingual brain is prepped for more than a second language

Lisa Seachrist Chiu
10:00am, December 31, 2014
street sign in english and chinese

A new study finds that bilingual people make efficient decisions on word choices, neural exercise that may protect the aging brain.

Laura Sanders is away on maternity leave. This week’s Growth Curve post is from freelance science and medical writer Lisa Seachrist Chiu, author of When a Gene Makes You Smell Like a Fish … and Other Amazing Tales about the Genes in Your Body. She is also a cofounder of Washington Yu Ying Public Charter School, a Chinese immersion school in Washington, D.C.
 

Just before winter break, my fifth grader came home from school, opened her mouth and produced what sounded to me like a stuttering mess of gibberish. After complaining that when she spends the entire day immersed in Chinese, she sometimes can’t figure out what language to use, she carried on speaking flawless English to me and Chinese to a friend while they did their homework. 

Quite honestly, I had been eagerly anticipating this very day for a long time.  Having worked several years to establish the Chinese language immersion elementary school my daughter attends, I could barely contain my excitement at this demonstration that she truly grasps a second language.

Early language programs are hot, in no small part because, when it comes to language, kids under the age of 7 are geniuses. Like many parents, I wanted my child to be fluent in as many languages as possible so she can communicate with more people and because it gives her a prime tool to explore different cultures.

Turns out, it may also benefit her brain. 

With the help of advanced imaging tools that reveal neural processes in specific brain structures, researchers are coalescing around the idea that fluency in more than one language heightens executive function — the ability to regulate and control cognitive processes.  It’s a radical shift from just a few decades ago when psychologists routinely warned against raising children who speak two languages, lest they become confused and suffer delays in learning.

One of the most intriguing aspects about bilingual people is that they are constantly activating both languages in their brains, says Viorica Marian, who studies the cognitive and neurological effects of bilingualism at Northwestern University.  So, for example, your brain starts guessing words the minute you hear even a fragment of a word. An English-only speaker might hear the word can and his or her brain activates the words candy and candle as possibilities.  Someone who speaks two languages will activate similar sounding words in both languages. The trick is to use the appropriate word.

To compare how bilingual and monolingual speakers accomplish this task, Marian and her colleagues had subjects perform a language comprehension task while observing what parts of the brain become active using functional magnetic resonance imaging. Volunteers ages 18 to 27 heard a series of words like cloud and were shown pictures that included clouds — and similar sounding words like clown. The subjects simply had to choose the picture that matched the word.

Bilingual people were no faster at completing the task than those who only speak one language, Marian and colleagues report in the December Brain & Language.  However, the monolingual volunteers were forced to activate regions in their brains associated with inhibition and executive control when completing this routine task.  Bilingual volunteers, because their brains are always filtering out words from another language, had very little activation in these brain regions. Those who spoke only one language were working harder.

In effect, routinely filtering out words from another language and using the appropriate language is such a potent workout for the brain that other tasks involving executive function are relatively easy.

That extra brain exercise may be crucial as we age.  Studies around the world show that bilingual people start showing the symptoms of Alzheimer’s disease about 5 years later than monolingual people. Most recently, Evy Woumans, Wouter Duyck and colleagues at the University in Ghent in Belgium reported in Bilingualism: Language and Cognition that bilingual Alzheimer’s patients developed significant symptoms on average 4.6 years later than monolingual Alzheimer’s patients and received their diagnoses 4.8 years later than monolingual people.  It’s important to note that Alzhiemer’s disease is not developing later in bilingual people — the numbers reflect that this group is dealing much better with the damage caused by the disease.

And, it turns out, language may have a stronger effect than education, socioeconomic status and participating in mentally taxing hobbies like playing music. Researchers at the University of Hyderabad, India, and the University of Edinburgh in Scotland demonstrated a similar bilingual advantage in the development of Alzheimer’s symptoms among subjects who were illiterate.

So, why would being bilingual have a greater effect than, say, playing the piano?  The answer may lie in the fact that we are constantly using language.  Anything that is hard to do is good for the brain: solving math problems, playing chess, playing music.  But engaging in any of those activities employs language because it requires thought. In effect, if you are bilingual, you are thinking twice.

So, maybe placing my child in a language immersion school will have lifelong benefits I never imagined.  

And, while l speak only one language, research is also telling me that it’s not too late to step up: A study published this month found that adults who took six months of Spanish language classes had improved executive function compared with those who didn’t study language.

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