Published on: March 29, 2012
by Sharon Kirkey for The Gazette
Bilingualism helps protect the aging brain and may even postpone signs of dementia, a new review of recent studies indicates.
The paper by Canadian researchers, published Thursday, suggests that bilingual people have higher cognitive reserves as they get older. Higher cognitive reserve is associated with a lower risk of Alzheimer’s and other memory-destroying dementias.
More than half the world’s population is bilingual, the researchers write in the journal Trends in Cognitive Sciences. In the United States and Canada, about 20 per cent of the population speaks a language other than English at home.
Lead author and psychologist Ellen Bialystok, of Toronto’s York University, had already begun accumulating evidence that the bilingual advantages seen in children could also be found in healthy adults. In a 2004 study, her team reported that bilingual adults, young and old, performed better than monolinguals on “conflict tasks” — situations where people need to ignore distracting stimuli to perform properly. (Think of driving on a busy highway).
In hundreds of interviews with reporters and science writers, Bialystok said, she kept being asked one question: What about dementia?
In a study published in 2007 involving about 200 Alzheimer’s patients, half of whom were lifelong bilinguals, her team found that the bilingual patients had been diagnosed 4 1/2 years later on in the disease than people who spoke only one language, a difference Bialystock calls “huge.”
Others have recently shown that bilingual Alzheimer’s patents are better able to cope with the disease and can function longer without showing symptoms, even when CT scans of their brains show more advanced “pathology” or disease.
It has to do with cognitive reserve, Bialystok says — “a building up of resilience that comes from certain experience that allows you to cope.
“If what you have to cope with is cognitive impairment from nasty things like Alzheimer’s disease, the finding is that (bilinguals) can appear to function for a longer time than they otherwise would,” she said. “Cognitive reserve is an extra resource that enables you to keep functioning.”
It’s not exactly clear why. But one theory is that managing two different languages boosts brain regions that are critical for general attention and cognitive control.
“We know that if you know two languages, and that there are two languages you could be speaking at any time, then both of those languages are always active — they’re always kind of ‘available’ in your mind,” she said. “That means that every time you want to say something or understand something or write something, there’s potential interference from the other language.”
When that happens, the brain’s executive-control system kicks in to manage the conflict between languages.
The executive-control system is the basis for our ability to multi-task and to stay focused on what’s relevant and avoid distraction.
In bilinguals, that brain network gets “massive practice,” said Bialystok, a Distinguished Research Professor at York.
The new science into aging bilingual brains has implications for children. “For parents, one important implication is not to be afraid of languages. You’re not damaging your children if you give them a variety of language experiences,” Bialystok said.
For older adults, “bilingualism is a very powerful road to cognitive reserve, and cognitive reserve is a very powerful defence against dementia,” she said. “It sort of comes for free to a lot of people who only have to keep up their heritage language, or keep up their languages.”
It’s not clear whether learning another language later in life could modify brain processing and give people this resilience in brain reserve.
“Will it make you bilingual if you start learning another language at age 57, or 62 or even 49? Probably not,” Bialystok said.
“But going through the process, which is effortful and requires a lot of sustained attention and a lot of executive control, that process, in its own way, is going to contribute to cognitive reserve.”
According to the Alzheimer’s Society of Canada, more than half a million Canadians have dementia, with roughly 71,000 of those under the age of 65.
The organization estimates that within a generation, about 1.1 million Canadians will be living with some form of dementia.
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