Bilingualism and dementia. Is there a link?
A new study from the Université de Montréal finds that the brains of bilingual people are more efficient and economical at completing cognitive tasks, which may be why they are less prone to dementia than monolinguals.
The study involved two groups of seniors, one of monolinguals and the other of bilinguals, who were asked to perform simple tasks (matching a push-button response with a particular colour code on a computer screen) while their brains were scanned for neural activity. The researchers found that the brains of the monolingual participants were involving more areas of the brain than bilinguals in order to complete the same task. Specifically, the monolingual brains involved high connectivity within five different regions of the brain in order to complete a task which bilingual brains performed by displaying high connectivity in only one.
“Overall, the evidence of the present study suggests that bilinguals rely on a highly connected network devoted to visuospatial processing,” say the study’s authors. “These findings support the notion that the bilingual brain is able to deal with interference by allocating fewer and more task-specific resources, as reflected by the support of a smaller, more integrated visuospatial hub.”
Researchers see the higher efficiency of the bilingual brain as likely having the effect of slowing down the aging process of the brain, especially with respect to the frontal lobe (central to complex cognition, emotional expression and problem solving), which itself is vulnerable to aging. The difference is explained by the notion that people who have learned more than one language are more adept at quickly picking out what’s important to the task at hand from a particular stream of information, and that this ability transfers into cognitive efficiency.
“After years of daily practice managing interference between two languages, bilinguals become experts at selecting relevant information and ignoring information that can distract from a task,” says Ana Inés Ansaldo, researcher at the Centre de recherche de l’Institut universitaire de gériatrie de Montréal and study co-author, in a press release. “In this case, bilinguals showed higher connectivity between visual processing areas located at the back of the brain.”
Previous research has shown that bilingualism is good for the aging brain and that learning a second language, even later in life, can help ward off dementia. A comprehensive study in 2013 of 648 patients with dementia, 391 of them being bilingual, found that overall bilingual patients developed dementia 4.5 years later than monolingual patients. Conducted at the University of Hyderabad in India, the study found that “the bilingual effect” on the onset age of dementia is independent of other factors such as sex, occupation, urban vs. rural living and even level of education.
“We have observed that bilingualism has a concrete impact on brain function and that this may have a positive impact on cognitive aging,” says Dr. Ansaldo. “We now need to study how this function translates to daily life, for example, when concentrating on one source of information instead of another, which is something we have to do every day. And we have yet to discover all the benefits of bilingualism.”
The new study is published in the Journal of Neurolinguistics.