Speaking two or more languages may protect against dementia, but bilingualism makes it harder to detect the disease

When words fail, Dr. Vanessa Taler is on the case. The University of Ottawa psychology professor has been investigating the link between memory impairment and language decline in people with Alzheimer’s disease.

“Language is my thing,” says the Bruyère Research Institute scientist. “My mom is Salvadoran. My grandmother is Russian. I learned French in Canada, Spanish in El Salvador, but grew up in New Zealand. I just always thought bilingualism was really cool.”

Although the trilingual researcher only spoke English as a child, her parents could communicate at any time in a mishmash of Serbo-Croatian, Russian or Spanish.

Taler's interests in sociolinguistics, psychology and dementia in aging populations intersected when she attended grad school in Montreal.

She knew that verbal deterioration has long been seen as a major indicator for onset of Alzheimer's disease. But Taler also noticed a problem with the way clinicians were assessing cognitive function.

The “picture-naming tasks” developed by Americans to evaluate language function decline were only normed to performance in one language, typically English.

So with an $118,000 grant from the Alzheimer Society Research Program, Taler and her team of researchers in Quebec City and Ottawa are developing diagnostic tools for bilingual French-English speakers.

“What I want to know is how we can diagnose the bilingual population in Canada,” she says. “That’s potentially a huge chunk of the population that clinicians are really challenged by.”

Amid a rising prevalence of Alzheimer’s disease due to longer life expectancies, Taler’s work could play an important role in helping assess onset of dementia in Canada.


Her picture-naming tasks would involve computers that present images on a screen for a patient to identify using whichever of the two languages the subject chooses. Based on the answers, an algorithm would decide which image to show next and whether to raise or lower the level of difficulty.

Taler notes that monolinguals and multilinguals process language differently.

“If you think about a mental dictionary, bilinguals have a whole bunch of other words in there that monolinguals don’t have, because the bilinguals have that second language,” she explains. “That can cause interference between the languages.”

It's why bilinguals tend to perform worse on language tasks, but that's not necessarily because they’re exhibiting onset of dementia.

“This is a major problem when you talk to clinicians,” Taler says. “Until now, it’s been difficult to assess bilingual patients due to a lack of adequate norms and language tasks for that population.” More than half the global population is multilingual. Close to one-fifth of Canadians speak both official languages.

“We know the population is aging, the presence of Alzheimer’s disease is increasing by virtue of the older population, and we need to do something about it,” Taler says.

“This is going to be a problem on multiple levels in Canada if we don’t get a handle on this issue.”

Beyond developing diagnostic tools for French-English bilinguals, Taler’s ultimate goal is to have other researchers expand the assessments to other language combinations.

For 25 years, the Alzheimer Society Research Program (ASRP) has been funding peer-reviewed Canadian research aimed at improving prevention, diagnosis and treatment, as well as finding a cure. To date, over $40 million has been invested in the work of researchers like Vanessa Taler.

Learn more about the
ASRP and other recipients’ work.
Learn more about Alzheimer’s disease and other dementias and how to reduce your risk.

Last Updated: 11/08/2017