It’s very difficult to predict whether we’re going to be afflicted with dementia in our old age. But if that’s the trajectory we’re on, we’d surely like to delay its onset as long as possible.
Newly published research from India suggests one way of doing that might be to learn a second language.
“This is the largest study so far documenting a delayed onset of dementia in bilingual patients,” a research team led by neurologist Suvarna Alladi of Nizam’s Institutes of Medical Sciences writes in the journal Neurology.
“Overall, bilingual patients developed dementia 4.5 years later than the monolingual ones.”
The paper provides evidence that bilingualism slows the onset of three different types of dementia. It’s also the first study to show this dynamic also applies to the illiterate—a finding that suggests the protective effect of bilingualism “cannot be reduced to differences in education.”
Over the past few years, several small-scale studies have been released suggesting that knowing a second language delays dementia. To see if they could obtain similar results in their home country, Alladi and her colleagues studied case records of 648 patients who were diagnosed with dementia at a specialized clinic. More than half of them, 391, were bilingual.
“Overall, bilingual patients developed dementia 4.5 years later than the monolingual ones,” the researchers write. This effect, they add, “was shown independently of other potential confounding factors such as education, sex, occupation, and urban vs. rural dwelling of subjects.”
The four-and-a-half-year delay “was almost identical to that reported in previous studies,” Alladi and her colleagues add. It was consistent in three different types of dementia: frontotemporal, vascular, and Alzheimer’s disease.
Exactly why speaking two or more languages seems to protect against dementia remain unclear. A 2011 Canadian study that examined the brain atrophy of Alzheimer’s patients tentatively concluded it increases one’s “cognitive reserve,” meaning one could suffer more damage to the brain before becoming symptomatic.
Alladi and her colleagues speculate that the practice of switching quickly from one language to another may keep one’s “attention and executive functions” sharp, acting as a buffer against encroaching dementia.
“Our results offer strong evidence for the protective effect of bilingualism against dementia, in a population radically different from populations studied so far,” they conclude.
In other words, speaking multiple language seems to serve as a buffer against some of our most feared brain disorders—even beyond the “weird” world.
