Short answer
Multilingual individuals might perform better in selecting and filtering relevant information throughout daily life.
Longer answer
More than half of the world’s population speaks more than one language. Does it influence the brain? Research on this topic is booming! However, the conclusions remain controversial. Before understanding why the answers are still debated, we will expose two effects multilingualism has on the brain at different life stages.
Speaking more than one language seems to improve cognitive function. People who speak multiple languages (multilinguals) have more words stored in memory than those who speak one language (monolinguals). They also know more verbal expressions, grammar rules, spelling patterns, ways of pronunciation, etc… Because multilinguals know multiple ways to refer to a certain thing, they have to choose between those options constantly. This has led some researchers to claim that the use of several languages requires a control mechanism to inhibit the non-selected language in favour of the more desired one. In this manner, multilinguals would generally be better at focusing on relevant information throughout daily life while ignoring distractions – defined in general terms as executive functions.
Later in life, multilingualism also provides additional benefits: the brains of people who speak multiple languages tend to remain healthier in old age. This may delay the development of neurodegenerative diseases such as Alzheimer’s disease. How does current research explain this? The age of our brain is partially determined by its ability to protect and repair itself against damage. This is referred to as cognitive reserve. Lifelong multilingualism seems to increase this cognitive reserve. However, at the level of brain cells, no difference between the brains of monolinguals and multilinguals has been identified so far.
Despite these findings, the direct link between multilingualism and brain changes is difficult to establish. Multilingualism is about more than just speaking multiple languages. It also depends on the language itself, when the languages were learned (early vs late bilingualism), on which level, or in which context they are used (for example, in daily life or formal education). These factors make multilingual populations highly heterogeneous, complicating the ability to draw universal conclusions. Future studies must account for these differences, as well as other variables like education, physical activity, socioeconomic status, etc…