Facts So Romantic

Speaking Multiple Languages Staves Off Dementia

Photography by Lemon Tree Images / Shutterstock

Parlez-vous francais? If you answered yes, then you’re well on your way to enjoying the many benefits of bilingualism. Speaking both English and French, for example, can enrich your cultural experiences in multilingual destinations like Belgium, Morocco, or Egypt, and broaden your access to books, music, and films.

But the benefits of speaking another language aren’t limited to just cultural perks. “Studies have shown that bilingual individuals consistently outperform their monolingual counterparts on tasks involving executive control,” says Ellen Bialystok, a cognitive psychologist at York University. In other words, speaking more than one language can improve your ability to pay attention, plan, solve problems, or switch between tasks (like making sure you don’t miss your freeway exit while attending to your kids in the back seat). You may think it’s just higher intelligence that underlies these benefits, but evidence suggests otherwise. A 2014 study, for example, showed that those who learned a second language, in youth or adulthood, had better executive functions than those who didn’t, even after accounting for childhood IQ.

But the benefits don’t end there. Being bilingual, or multilingual, could lead to a longer, higher quality life. In a paper published in March, Bialystok and colleagues report that older individuals who speak more than one language have better cognitive performance and a later onset—around 4 to 5 years—of dementia than their monolingual peers. These striking cognitive benefits have profound public health implications. Delaying the onset of dementia by just a few years would drastically reduce rates of Alzheimer’s disease, which currently affects over 5 million Americans, and could cut healthcare costs by a third. “At present, the best defense against dementia is the set of stimulating cognitive activities that are considered to supply ‘cognitive reserve,’ things such as social groups, crossword puzzles, etc,” Bialystok says. “Bilingualism is another such activity but has the unique bonus of also enabling someone to speak another language—something that is certainly a net benefit in life.”

Learning a new language may be an easy and enjoyable way to maintain brain health and improve cognitive function.

The concept of cognitive reserve is not new. Scientists have long known that a stimulating environment—like learning new things and keeping an active social life—can make the brain more resilient to the detrimental effects of aging or disease. There’s overwhelming evidence, for example, that higher education, exercising, being socially active, or holding a demanding job can help maintain normal cognitive functioning into older age. The addition of bilingualism to this list is particularly good news since going back to school for a higher degree, or changing occupations, isn’t practical for many of us. Along with other activities such as taking a dance class or going out with a friend, learning a new language may be an easy and enjoyable way to maintain brain health and improve cognitive function.

Four years of intensive foreign language study, for example, has been found to improve executive control. In another study, which Bialystok co-authored, two groups of around 30 students were tested on a series of executive control tasks. Then one group—the “training group”—enrolled in an introductory Spanish course. After six months, they displayed different neural activity during the executive control test than they did initially, “indicating enhanced performance,” the researchers found. The other student group, enrolled in a psychology course, did not show improvement on the tests after the same period.

It shouldn’t be surprising that the brain’s executive functions benefit from bilingualism: It’s possible that speaking more than one language exercises them, like a muscle, making them stronger and more robust to the harms of aging. Brain imaging studies, for example, have confirmed that bilingual brains are structurally and functionally different from those of monolinguals. The volume of gray matter—containing the bodies of neurons—has been found to be greater across the brain, including in the frontal cortex, inferior parietal lobe and temporal pole, for bilinguals than monolinguals. These regions are critical for an array of cognitive functions, including memory and attention, and have been found to shrink with age or neurodegenerative disease. This suggests that speaking a second language does in fact reshape the brain in positive ways.

There’s an alternative explanation, however, to the “cognitive reserve” theory. Speaking multiple languages may instead encourage the brain to adopt advantageous compensatory functions. It could be the case, for example, that the same aging-related defects occur in both bilingual and monolingual brains, but bilinguals have adapted means to recruit other neural resources to make up for these impairments. In other words, although bilingualism may not strengthen the brain, it might grant the brain alternative methods to cope with the detriments of aging. A 2012 study supports this. The researchers observed that, although bilinguals and monolinguals were matched for cognitive function, “bilingual patients with Alzheimer’s disease exhibited substantially greater amounts of brain atrophy than monolingual patients in areas traditionally used to distinguish AD patients from healthy controls.” Bilingualism requires, they concluded, “greater amounts of neuropathology before the disease is manifest.” Thus it’s possible that bilingualism allows a degenerating brain to otherwise function normally, at least temporarily.

However, not all multilinguals enjoy identical neural benefits—there’s some evidence for a language dose effect. A 2013 study found that “the probability of being later free of cognitive impairment increased up to four times along with the number of practiced languages through life.” So taking a year of high school Spanish, unfortunately, probably isn’t going to go very far; bilinguals need to speak both languages regularly into old age to reap full benefits. “The effects of bilingualism on cognitive processing can be traced to both the degree of proficiency and extent of use of both languages,” Bialystok explains. “Becoming bilingual early in childhood is generally associated with larger effects, but the consequences of bilingualism can be seen even in very late bilinguals.” More bilingual experience, or more intense usage, she says, is likely to be associated with larger outcomes.

It’s less clear why bilingualism would confer resilience to Alzheimer’s disease, which is primarily a memory disorder. “There is little evidence that in general bilingualism helps memory,” says Bialystok. She instead suspects “that the more intact frontal regions, responsible for executive function, compensate for the declining memory associated with degeneration in medial temporal structures. Hence, bilingualism does not prevent dementia but rather provides a means for compensating for the symptoms of dementia, at least in the early stages.”

But just how practical is it to “prescribe” learning a new language? Bialystok believes that part of the solution lies in a long-term approach to education. “Foreign language education has become very unpopular in recent decades,” she says, “and it is clear from our studies that schools should provide many more opportunities for language learning to children.” Speaking many languages may not be a neural panacea, but it appears to be one of many key factors for lifelong brain health.

Emilie Reas, a science writer and postdoctoral fellow at the University of California, San Diego, studies how the brain changes with aging and Alzheimer’s disease. Follow her on Twitter @etreas.

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