Individuals who speak two or more languages, even those who acquired the second language in adulthood, may slow down cognitive decline from aging, according to new research published in the Annals of Neurology.
Bilingualism is thought to improve cognition and delay dementia in older adults. While prior research has investigated the impact of learning more than one language, ruling out ‘reverse causality’ has proven difficult. The crucial question is whether people improve their cognitive functions through learning new languages or whether those with better baseline cognitive functions are more likely to become bilingual.
In a new study, lead author Dr Thomas Bak of the University of Edinburgh’s Center for Cognitive Aging and Cognitive Epidemiology and his colleagues relied on data from the Lothian Birth Cohort 1936, comprised of 835 native speakers of English who were born and living in the area of Edinburgh, Scotland.
“Our study is the first to examine whether learning a second language impacts cognitive performance later in life while controlling for childhood intelligence,” Dr Bak said.
“The Lothian Birth Cohort offers a unique opportunity to study the interaction between bilingualism and cognitive aging, taking into account the cognitive abilities predating the acquisition of a second language.”
The participants were given an intelligence test in 1947 at age 11 years and retested in their early 70s, between 2008 and 2010.
262 participants reported to be able to communicate in at least one language other than English.
Of those, 195 learned the second language before age 18, 65 thereafter.
The findings of the study indicate that those who spoke two or more languages had significantly better cognitive abilities compared to what would be expected from their baseline.
The strongest effects were seen in general intelligence and reading. The effects were present in those who acquired their second language early as well as late.
“These findings are of considerable practical relevance. Millions of people around the world acquire their second language later in life. Our study shows that bilingualism, even when acquired in adulthood, may benefit the aging brain,” Dr Bak concluded.
Thomas H. Bak MD et al. Does bilingualism influence cognitive aging? Annals of Neurology, published online June 02, 2014; doi: 10.1002/ana.24158