People who spoke two languages on a daily basis scored higher on several cognitive tests than those who only spoke one language, according to a new study published in Neurobiology of Aging — findings that suggest bilingualism could be protective against dementia and cognitive decline in older adults.
According to the New York Times, researchers have been studying the potential impact of bilingualism on the aging brain for decades. So far, research has suggested that bilingualism could prevent cognitive decline and reduce the risk of dementia in later life, but there is still no clear consensus on the potential benefits.
In a new study, researchers in Germany assessed bilingualism at three life stages (early, middle, and late) in 746 participants ages 59 to 75. Around 40% of participants had no memory problems while the remainder were patients at memory clinics and had reported memory loss or confusion.
All the participants were tested on vocabulary, memory, attention, and calculation tasks. Some of the tasks included recalling objects that were previously named, spelling words backwards, following three-step commands, and copying designs shown to them.
Overall, the researchers found that participants who reported using a second language every day in the early (ages 13 to 30) or middle (30 to 65) stages of their lives scored higher on language, memory, attention, focus, and decision-making abilities compared to people who only spoke one language during those times.
According to the Times, neuroscientists have hypothesized that skills associated with being able to switch fluidly between different languages — like multitasking, emotion management, and self-control — may help bilingual speakers delay dementia.
Boon Lead Tee, a neurologist at the University of California, San Francisco, said that the researchers took a unique approach to their study by investigating bilingualism at different life stages. In addition, she said that the large sample size would likely allow the researchers to evaluate other questions, such as whether the age a person initially learned each language impacted their cognition later in life.
Separately, Miguel Arce Rentería, a neuropsychologist at Columbia University, said, "It's promising that they report that early and middle-life bilingualism has a beneficial effect on cognitive health in later life" and that the findings "line up with the existing literature."
However, Tee noted that study only evaluated one aspect of bilingualism, which was using two languages every day over a long period of time. Because of this, the positive impact on cognition observed in the study might have been due to other factors, such as the age when the two languages were encoded or participants' specific demographics or life experiences.
Other experts have agreed with Tee's assessment, saying that the findings might have been different if researchers had recruited individuals who spoke a second language less frequently.
"I think there isn't a definition that everybody agrees upon, and I think there will never be because being a bilingual is a full spectrum," said Esti Blanco-Elorrieta, a language researcher at Harvard University.
In addition, Blanco-Elorrieta said that it's crucial that future research examine the broader benefits of bilingualism outside of its potential impact on cognitive tests.
"The advantage of being bilingual doesn't really lie on these milliseconds of advantage that one can have in a cognitive task," she said. "I think the importance of being bilingual is being able to communicate with two cultures and two ways of seeing the world." (Padmanabhan, New York Times, 4/28; Ballarini et al., Neurobiology of Aging, accessed 4/28)
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