Bilingual speakers get dementia later in life, Canadian study finds

Steve Mertl
National Affairs Contributor
Daily Brew

Here's another good reason to have paid attention in French class, other than the dwindling prospect of a federal public-service job.

Being bilingual may help slow the onset of dementia symptoms, according to a Canadian study.

CBC News reports researchers at Toronto's York University looked at hospital records of dementia patients who were either monolingual or bilingual. They found bilingual patients were diagnosed with dementia three to four years after those who spoke only one language. The average age of diagnosis was 75.4 years for unilingual patients, compared with 78.6 years for bilinguals, who spoke a range of different languages.

Results of the study were published in the April edition of the scientific journal Trends in Cognitive Sciences.

Psychologist Ellen Bialystok, the article's lead author, had previously studied the advantages healthy bilingual children and adults have in brain function, such as being able to solve problems when dealing with distracting stimuli.

In a 2007 study involving some 200 Alzheimer's patients, half of them bilingual, her team found bilinguals were diagnosed four and a half years later than unilingual patients, Postmedia News reported.

That's a huge difference, Bialystok said. Other research has shown bilingual Alzheimer's patients are better able to cope and function longer without showing symptoms even when brain scans show the disease has advanced, Postmedia reported.

Bialystok said bilingual dementia patients have built up a cognitive reserve through managing two languages.

"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 told Postmedia News. "Cognitive reserve is an extra resource that enables you to keep functioning."

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," Bialystok 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."

The brain's executive-control system then steps in to manage the conflict, she said.