November 8, 2013
Speaking More Than One Language Delays Dementia
Besides being able to navigate in two or more cultures, people who speak more than one language have a lower risk for developing earlier dementia, according to a new study published in the journal Neurology. In the study, a team of British and Indian scientists tracked nearly 650 dementia patients, taking note of when each patient was diagnosed with the condition. The researchers found that individuals who speak more than one language and who are diagnosed with dementia tend to receive their diagnosis up to five years later than those who speak only one language.
"We know from other studies that mental activity has a certain protective effect," study author Thomas Bak, a neurologist at the University of Edinburgh in Scotland told USA Today. "Bilingualism combines a lot of different mental activities. You have to switch sounds, concepts, grammatical structures, cultural concepts. It stimulates your brain all the time."
The research found that the correlation even extended to illiterate individuals — suggesting that the effect has nothing to do with formal education. When the team compared data for illiterate people, those who could speak more than one language were diagnosed with dementia six years later on average.
For the study, the scientists reviewed the medical records of patients who visited a clinic in the city of Hyderabad, the largest city of the southern Indian state of Andhra Pradesh. The team said that selecting this location was important because residents of the city often speak two or three language - typically some combination of India's official language, a local dialect, and English.
"Since bilingualism is more of a norm in India, bilingualism is not a characteristic of any particular socioeconomic, geographic or religious group," said Suvarna Alladi, a neurologist at Nizam's Institute of Medical Sciences, Hyderabad.
Over 50 percent of the people diagnosed with dementia at the clinic spoke more than one language, the researchers said. However, the team found that bilinguals and multilinguals developed their initial symptoms at an average age of 65.6 — five years later than the average of 61.1 for those who spoke just one language. The differences were seen for the diagnosis of Alzheimer's disease, vascular dementia and frontotemporal dementia, which is caused by deterioration of the brain's frontal or temporal lobes.
The new study echoes findings from two previous smaller studies conducted in Canada that found a later onset of Alzheimer's disease in bilingual individuals. However, the bilinguals in those studies were mostly immigrants, raising doubt about whether they were different from the general population, according Brian Gold, a neuroscientist at the University of Kentucky.
Though not a part of the newly released study, Gold told USA Today the UK and Indian team’s findings a more convincing, "because it is studying bilingual people raised in the same country and culture."
He added that the study reinforces the idea of exposing children to multiple languages as they grow and for bilingual families to keep teaching their kids the languages they know. He said it was unclear if people can affect their risk of developing dementia by taking up a second language later in life.
"It may never be too late," Bak said, noting that it’s uncertain if bilingual people are any better off once symptoms of dementia take hold.