It was suggested that lifelong bilingualism may protect against dementia, if both languages are used frequently throughout life.
Dementia is the largest cause of dependency and disability in older adults, affecting millions of people worldwide.
It has been suggested that bilingualism, where an individual speaks two or more languages, may delay the development of dementia. But what evidence is there for this?
My recent paper, published in the Journal of European Psychology Students, reviewed the evidence, using a series of nine studies published in scientific journals. Participants in the studies spoke a variety of languages (e.g. English, French, Spanish) and differed in terms of participant characteristics (i.e. education status and immigration status).
Some studies found that bilinguals were diagnosed with dementia several years later than monolinguals, even after controlling for demographic variables (such as age and education status).
However, others found no significant differences between bilinguals and monolinguals. The methods used between studies also differed substantially, with some examining medical records of patients already diagnosed with dementia, and others following healthy older adults over a period of several years.