A lifetime of speaking two or more languages appears to pay off in old age, with recent research showing the symptoms of dementia can be delayed by an average of four years in bilingual people, wrote The Wall Street Journal online Oct. 11:
Over time, regularly speaking more than one language appears to strengthen skills that boost the brain’s so-called cognitive reserve, a capacity to work even when stressed or damaged. This build-up of cognitive reserve appears to help bilingual people as they age.
“Speaking two languages isn’t going to do anything to dodge the bullet” of getting Alzheimer’s disease or dementia, says Ellen Bialystok, Distinguished Research Professor in Psychology in York University’s Faculty of Health. But greater cognitive reserve means the “same as the reserve tank in a car: Once the brain runs out of fuel, it can go a little farther,” she says.
Specifically, the advantages of bilingualism are thought to be related to a brain function known as inhibitory or cognitive control: the ability to stop paying attention to one thing and focus on something else, says Bialystok. Fluent speakers of more than one language have to use this skill continually to silence one language in their minds while communicating in another.
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Dr. Bialystok began her decades-long research by studying how children learn a second language. In 2004, she and her colleague Fergus Craik shifted to conduct three studies looking at the cognitive effects in some 150 monolingual and bilingual people between 30 and 80 years old.
They found that in both middle and old age, the bilingual subjects were better able to block out distracting information than the single-language speakers in a series of computerized tests. The advantage was even more pronounced in the older subjects.
Dr. Bialystok says other research also shows better performance from bilingual people on tests requiring cognitive control, such as when they are instructed to determine whether a sentence is grammatically correct, even if the content doesn't make sense.
For example, in distinguishing, "apples grow on trees" from "apple trees on grow" and "apples grow on noses," the third sentence requires people to focus on the structure and suppress paying attention to the meaning of the words.
The findings from the 2004 study led Dr. Bialystok to wonder whether these benefits might help older people compensate for age-related losses in learning.
She and her colleagues examined the medical records of 228 memory-clinic patients who had been diagnosed with different kinds of dementia, two-thirds with Alzheimer's disease.
The results, published in the journal Neuropsychologia in 2007, suggested that bilingual patients exhibit problematic memory problems later than those who only spoke one language.
Bilingual patients were, on average, four years older than single-language speakers when their families first noticed memory problems, or when the patient first came to the clinic seeking treatment.
Moreover, bilingual patients' memories were no worse than those of single-language speakers by the time they arrived at the clinic, and there was no difference in the length of time between the detection of symptoms and when the patients were first checked in.
In a subsequent study, Dr. Bialystok and her colleagues looked at brain images of monolingual and bilingual Alzheimer's patients at the same age and stage of disease.
They found that the brains of the bilingual people appeared to be in worse physical condition. This suggests that bilingualism doesn't delay the disease process itself, but rather helps bilingual individuals better handle memory deficits, Dr. Bialystok says.
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Dr. Bialystok's group is now conducting a study testing patients every six months to measure the rate of mental decline over the course of dementia.
Bialystok's research was also covered by the Daily Mail Oct. 12.
Republished courtesy of YFile– York University’s daily e-bulletin