A fascinating paper published Thursday in the April issue of the journal Trends in Cognitive Sciences suggests that being bilingual may slow the development of dementia among older adults.

In a review of research on the cognitive effects of communicating in more than one language, psychologists led by Ellen Bialystok of the University of York in Toronto found that while the brain-health benefit of bilingualism among adults is “muted,” among older people it becomes more pronounced. For instance, a study of older people with dementia found that those who were bilingual showed symptoms of dementia about three to four years later than those who communicated in a single language — at about at 78.6 for bilingual subjects versus 75.4 for monolingual people. A second study of people with Alzheimer’s disease, a form of dementia, showed similar results, the paper reports.

The paper suggests that the brains of people who juggle more than one language may be kept agile by the constant business of determining which words, from which language, to use and other complex behaviors associated with sorting out patterns of letters and making sense of them. That invokes the brain’s “executive function,” a sophisticated system of controls that matures late in brain development and that supports such activities as “high-level thought, multi-tasking, and sustained attention.” The repeated experience of switching between two languages may also contribute to “brain flexibility” and may actually alter the structure of the brain, the paper notes. All that mental stimulation may contribute to bilingual people’s amassing greater “cognitive reserve,” a kind of bank account of brain skills that may protect against the cognitive decline associated with dementia.

If you’re like me, you’re already pricing Rosetta Stone kits on Amazon.com. Alas, the authors explain that their work examines mostly people who have been bilingual all their lives — and not necessarily by choice, but by virtue of their having been born into circumstances requiring them to communicate in more than one language. In a sidebar labeled “How bilingual?” the authors write, “If bilingualism is protective against some forms of dementia, then middle-aged people will want to know whether it is too late to learn another language, or whether their high-school French will count towards cognitive reserve. A related question concerns the age of acquisition of a second language: is earlier better? The best answer at present is that early age of acquisition, overall fluency, frequency of use, levels of literacy and grammatical accuracy all contribute to the bilingual advantage, with no single factor being decisive.”

Are you bilingual? Do you feel being bilingual gives your brain a good workout?