Short answer
People who speak more than one language might be better at focussing on the relevant information in daily life than people who only speak one. Also, their brains tend to remain healthier as they age.
Longer answer
More than half of the world population speaks more than one language. Do the brains of people who speak more than one language differ from those who don’t? Research on this topic is booming! However, the conclusions remain controversial. Before explaining why the answer to this question is still debated, let’s dive into two effects that multilingualism appears to have on the brain.
Multilingualism may improve cognitive function
Speaking more than one language seems to improve cognitive function. People who speak multiple languages (multilinguals) have more words stored in memory compared to people 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 say a certain thing, they have to constantly choose between those options. This has led some researchers to claim that speaking multiple languages requires a control mechanism to inhibit the non-selected language in favor of the wanted one. This way, multilinguals would be generally better at focusing on the relevant information in daily life while ignoring distractions.
Multilingualism may protect the brain from aging
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 the current research explain this? The age of our brain is partially determined by its ability to protect and repair itself against damage: the “cognitive reserve”. Lifelong multilingualism seems to increase this cognitive reserve. However, at the level of brain cells, no difference between brains of monolinguals and multilinguals has been so far identified.
Challenges in Studying Multilingualism
A direct link between multilingualism and brain changes remains difficult to establish. The effects of multilingualism are not simply the result of speaking multiple languages. The effects depend on which languages are spoken, 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 in 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, and socio-economic status, so that we will hopefully in the future better understand how speaking multiple languages influences the brein… Oops, I mean BRAIN…