Bilingual people begin to experience symptoms of Alzheimer's and other forms of dementia about 4.5 years later than those who speak only one language – even when factors like education level and literacy are factored in, a new study found.
The study, published in the journal Neurology, examined the records of 648 people with three different types of dementia, including Alzheimer's, who attended a memory clinic in India between June 2006 and October 2012. Nearly half of the patients spoke more than one language since early childhood.
Experts say there have been similar findings in the past – so the most recent study, carried out by researchers from Edinburgh University in the United Kingdom and Nizam's Institute of Medical Sciences in Hyderabad, India, was not startling.
"I'm not totally surprised" about the new study, said Adrián García-Sierra, a Mexican-born research scientist at the University of Connecticut who has done work on bilingualism and brain functions, mentions. "The bilingual brain has to work a little harder to sort through all this ambiguity in sound and meaning."
Canadian psychologist Ellen Bialystok published similar findings in 2007, though the new study is more than three times its size. There have also been studies showing that regularly solving Sudoku or crossword puzzles can help delay the onset of dementia.
In his own research, García-Sierra found that people who speak more than one language since childhood, "can focus their attention better. In a setting with a lot of background noise like at a loud restaurant, most people's attention breaks down. But bilinguals are better able to pick up verbal cues – the big difference is that they can focus that attention longer."
Which is almost exactly what the Neurology study has found, García-Sierra points out – but in a scale that last years, not minutes.