Speaking two languages throughout life may slow the loss of mental agility that comes with age.
When seniors were challenged to switch between two basic thought tasks, bilinguals reacted more quickly than those who spoke only English. What's more, imaging scans showed that older people who had always spoken two languages used their brains more efficiently than single-language speakers.
The findings add to growing evidence that, along with other mentally stimulating activities, speaking multiple languages from a young age can help buffer the brain from aging-related declines.
Bilingualism "doesn't make you young like a young adult, but it makes you faster than your peers who only speak one language," said Brian Gold, a neuroscientist at the University of Kentucky, Lexington.
"For a long time, sending your kids to school in another language was something that people thought suspiciously about," he added. "Not only is that not true, sending your kids to immersion schools is a good thing. If they can keep it up, it will not only help them as a child. It will also help them as they age."
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A growing number of studies in recent years have pointed to the benefits of bilingualism. There is research to suggest, for example, that people who speak multiple languages are better at other kinds of multi-tasking, too, with the greatest differences showing up youth and in old age.
The idea is that, by learning to switch easily between languages, the brain becomes skilled at taking control over the tasks it's working on at any given moment and at suppressing information it doesn't need. This sort of cognitive flexibility is important in many areas of life, but it tends to decline with age.
To figure out how exactly bilingualism might boost brain functioning, Gold and colleagues put 80 people in an MRI machine that showed patterns of oxygen flow in their brains as they performed a basic task: While looking at a circle or square that was red or blue, participants pressed a button in response to a question about the object's shape or color. Participants were split equally between bilinguals and single-language speakers. Half were young adults. The other half were in their 60s.
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At first, people answered questions in clusters about an object's shape or its color. When the category switched unpredictably between shape and color, though, it took people longer to react. And, as in previous studies that used this kind of protocol, older people slowed the most.
But when the researchers compared the performance of the seniors in the experiment, they found that older people who spoke two languages fluently were faster than their only-English speaking peers at switching from one category to another.
In the brains of the older bilinguals, there was also less activity in the prefontal cortex and anterior cingular cortex -- two areas involved in controlling what the brain is doing, not just regarding language but in general. In other words, the older bilingual brain appears to function more efficiently than the older monolingual brain -- using less energy to complete the same kinds of brain processing tasks.
When it came to speed, performance for older bilinguals fell in between that of younger bilinguals and older monolinguals. And the same was true for brain activity, suggesting that speaking two languages doesn't stop aging-related declines but might help slow down the process.
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"This confirms a substantial body of literature and shows there are indeed aspects of control that are preserved in bilinguals," said Ellen Bialystok, a professor of psychology who researches bilingualism at York University in Toronto. "But the more exciting thing this paper does is contribute importantly to the story of why bilinguals do better on these tasks."
Long considered by many to be a liability, Bialystok added, bilingualism should be seen as a major asset that is worth nurturing.
"If you are, for reasons of life and immigration and circumstance, bilingual, this is something you can maintain in your life and pass on to your children," she said, "You can encourage and support and argue for a much more positive public view of bilinguals."
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Speaking two languages isn't the only way to fight back against aging's assault on the brain. Other research offers strong evidence for the protective effects of physical exercise and crossword puzzles, among other stimulating behaviors. The new research into bilingualism may help show how all sorts of activities like these offer benefits.
"Certainly the more efficient you can make the brain when you're younger, the more likely it is to have less decline with aging," said Matt Leonard, a neuroscientist at the University of California, San Francisco.
"The cognitive decline issue is going to become a serious issue as the population ages, and purely from an economic standpoint, there is a lot of money we'll need to spend to treat it," he added. "If there are ways to prevent that starting when people are younger, that is something that is becoming a really big area of focus."