TORONTO – A small study has found that people who speak more than one language have twice as much brain damage as those who are unilingual before they begin exhibiting symptoms of Alzheimer’s disease.
The finding suggests that being bilingual somehow conserves cognitive function for some time, despite there being areas of brain cells destroyed by the disease.
The study by a team of Toronto researchers, which analyzed brain scans of patients with probable Alzheimer’s disease, is being called the first to provide physical evidence confirming observational studies suggesting speaking more than one language is beneficial for the brain.
To conduct the study, the researchers studied the CT scans of 40 patients whose cognitive skills – including attention, memory, planning and organizational abilities – were found on testing to be similar. Half the patients were fluently bilingual while the other half spoke only one language.
Tom Schweizer, a neuroscientist at St. Michael’s Hospital who led the study published in the journal Cortex, said researchers analyzed how much damage had occurred in a certain area of the brain linked to Alzheimer’s disease in each of the patients.
“And to our surprise, the bilingual patients had twice as much atrophy in that area, despite the fact that they were maintaining their function and cognitive levels just as well as the monolingual patient,” he said Thursday.
“So that was quite striking. That was extremely counterintuitive to most people, because if you have more disease burden and your brain looks more damaged, you should be performing worse.
“So there’s something afforded by this bilingualism and we think it’s mapped onto this idea of cognitive reserve.”
Previous observational studies have found that bilingualism delays the onset of Alzheimer’s symptoms by up to five years, and this research adds the physical proof, Schweizer added.
Individuals who speak more than one language are constantly using their brain and keeping it active, which may contribute to overall brain health, he said. That’s why many physicians encourage older people to do crossword or Sudoku puzzles.
“The issue here, though, is bilingualism is the constant use of a second language by switching from one language to another, suppressing or inhibiting one language in favour of another,” he said. “These are all cognitive operations that you’re doing all the time when you’re bilingual.”
While the exact mechanism isn’t known, scientists suspect that giving the brain a constant workout juggling languages may allow a person to create enhanced neural networks that get around damaged areas in the brain.
Dr. Howard Chertkow, a professor of neurology at McGill University, said that despite the study’s small size and the fact that CT scans are not as accurate or detailed as MRIs, the research adds to the evidence that speaking more than one language can help preserve brain function.
The study takes a different approach to say “bilingualism is good, speaking more languages is good for the brain and there’s no downside,” said Chertkow, who was not involved in this study but has researched dementia in people who speak three or four languages.
“This is another plus side: it’s good for kids, it’s good for teenagers, it’s good for older adults as well in a totally different way,” he said from Montreal. “It helps build the brain to some extent and that’s a good thing to do.
“Parents who say I want my kids to be bilingual, this is another reason to do it.”
The study results are particularly significant for Canada, which is officially bilingual and has large numbers of immigrants for whom French and English are at least second languages. For many of the patients in this study, their second language was French, English or Chinese.
Although being bilingual appears to stave off onset of the symptoms, Schweizer stressed that bilingualism does not prevent someone from developing Alzheimer’s. Once symptoms start to appear in bilingual people, it is not clear whether the disease progresses at an accelerated rate.
He said the next step would be to repeat the study in a larger sample of patients, followed over time and using more sophisticated MRI analysis.
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