Comment Lutter Contre la Démence

If you can read this headline, you may be poised to resist a decline into Alzheimer's better than someone who speaks just one language.


There are many ways to challenge the brain, including music, exercise, and problem-solving games. Keeping the brain engaged has been shown to combat cognitive decline and delay the onset of Alzheimer’s disease. For researchers in this area, multilingualism is emerging as a key way to keep the mind sharp.

York University researchers have found that bilingual patients with mild cognitive decline may be able to resist the decline into full-blown Alzheimer’s disease longer than their monolingual counterparts. The catch is that when they do succumb, the decline is more rapid and severe than that of a monolingual patient.

The researchers suspect that their bilingualism allows them to compensate for their underlying decline by reinforcing their mental defences. This means they can live for potentially years longer than monolinguals without showing symptoms, but the defences can only hold for so long before the disease wins out.

Lead author Ellen Bialystok put it this way in the university’s press release: “Imagine sandbags holding back the floodgates of a river,” she said. “At some point, the river is going to win. When they can no longer do this, the floodgates get completely washed out, so they crash faster. Yet they had more time to enjoy the dry land.”

The study builds upon previous work showing an association between bilingualism and resisting cognitive decline. The paper is also thought to be the first to compare the conversion time of patients with mild cognitive impairment to Alzheimer’s disease in bilingual and monolingual people.

Separate research exploring multilingualism using data from the ‘Nun Study’ found similar results for those with four or more languages but was unable to find a significant association among bilingual speakers.

Language engages more of the brain, more frequently

Language is especially useful for delivering neuroplastic benefits because we use it all throughout the day and it engages regions all over the brain, explained Bialystok to the Globe and Mail. Bilinguals can’t ‘switch off’ one language or another, so even though they may not be aware of it, they are constantly selecting the one they need in the moment.

“That kind of selection is an ongoing cognitive demand of bilingualism,” she said.

Over five years, the team followed 83 monolingual and 75 bilingual patients with mild cognitive impairment. In the paper, the monolingual group were classified as having low cognitive reserve, while the bilinguals were marked as having high cognitive reserve.

Simply put, cognitive reserve refers to the brain’s ability to improvise and find different ways to get the work done in spite of challenges. When the brain faces damage, functionality can wane, but a brain with high cognitive reserve may compensate for the loss by enlisting different approaches to cognitive processing.

Researchers believe that cognitive reserve may act as a moderator between pathology and clinical outcome in the context of Alzheimer’s.

Age, education levels, immigration status, sex, and cognitive levels were all accounted for in the study. Bilinguals were, on average, two years older than monolinguals at the time of their mild cognitive impairment diagnosis. The team kept track of the patients’ biannual appointments to note the point at which these diagnoses progressed from mild cognitive impairment to Alzheimer’s disease.

For bilinguals, it took roughly 1.8 years after their initial diagnosis to make the conversion as opposed to 2.6 years with monolinguals. The suspected reason for this is that once the bilinguals crossed the clinical threshold for mild cognitive impairment, there was already a larger accumulation of amyloid plaques and tangles in the brain (major risk factors for Alzheimer’s), making the decline more rapid.

Despite the quicker descent of the bilinguals, they were significantly older than monolinguals at the time of their initial diagnosis, so they ultimately enjoyed more of the “dry land”, as Bialystok described it.

Alternatives exist for monolinguals

It’s still unknown just what level of ability counts in this context — the age at which we learn and whether certain languages or combinations have a stronger effect remain open questions.

Monolinguals shouldn’t despair though: “As long as you’re using your brain in stimulating ways, you’re helping cognitive reserve,” she says. “If not language, then just make sure you’re doing something,” says Bialystok.

Since there is currently no cure for Alzheimer’s, maximizing people’s ability to function and maintain independence remains the priority.

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Barry is a journalist, editor, and marketer for several media outlets including HeadStuff, The Media Editor, and Buttonmasher Magazine. He earned his Master of the Arts in Journalism from Dublin City University in 2017 and moved to Toronto to pursue a career in the media. Barry is passionate about communicating and debating culture, science, and politics and their collective global impact.