It has long been established that learning a foreign language helps improve brain health, yet scientists have still not been able to prove exactly how significantly this affects the brain’s condition.
Recent research suggests that the benefits may be far greater than many had anticipated. In individuals who speak four languages, the brain appeared to be roughly 13 years younger compared to those who speak only one language.
The advantage grew with each additional language. It was even more pronounced among those who had learned a second language at an early age or had achieved a high level of proficiency in it.
These findings indicate that multilingualism could help slow down brain aging, reinforcing a growing body of evidence that learning languages might be one of the simplest ways to enhance the brain’s long-term resilience.
To measure the rate of brain aging, a team of researchers led by Lucía Amoruso from the Basque Center for Cognition, Brain and Language (BCBL) in San Sebastián, Spain, developed what they refer to as “aging clocks.”
These clocks determine a person’s biological age and then compare it with their actual age. The clocks were built using data gathered from 728 adults. The researchers recorded each individual’s brain activity by measuring the weak magnetic fields generated when nerve cells are activated.
They then employed artificial intelligence to analyze what normal brain communication looks like at different ages. After creating the clock, the team tested it on a second group of 144 individuals from the Basque Country in Spain.
The volunteers spoke between one and four languages, including Spanish, Basque, French, and English. This allowed the researchers to compare the brain age of people with varying levels of language experience.
One conclusion was clear. Amoruso stated, “The main finding is that a richer language experience appears to be beneficial for brain health.”
The brains of people who spoke two languages looked approximately six years younger than those of people who spoke only one language. The gap widened with each additional year. Knowing three languages extended this gap by about seven years, while knowing four languages extended it by roughly 13 years.
The number of languages is not the whole story. People who learned their second language earlier or spoke it more fluently tended to show an even younger-looking brain.
“What surprised us most was how clearly the benefits appeared in the form of a gradient, rather than a simple ‘bilingual versus monolingual’ effect,” said Amoruso.
This effect resembles not an on-off switch, but a scale of multilingual experience, where depth and duration seem to matter.
A younger-looking brain also tended to maintain more distinctly organized communication networks. Each system remained specialized for performing its own task, rather than merging together, as often happens with aging in brain networks.
The idea that speaking multiple languages protects the brain is not new. Researchers have been debating it for many years.
One influential study conducted in India involving hundreds of dementia patients found that bilingual individuals developed symptoms roughly four and a half years later than those who spoke only one language, regardless of their education level.
Not all studies have identified this advantage. Some large-scale studies have found no clear benefit.
Much of the early research was based on small groups, focused on people already attending memory disorder clinics, and struggled to separate language skills from factors such as wealth, education, and other advantages.
The same research group behind the aging clock recently tackled this issue on a much larger scale.
In a study covering more than 86,000 people across 27 European countries, researchers discovered that residents of regions with high levels of multilingualism were more than twice as likely to avoid signs of accelerated aging.
This pattern held even after the team accounted for differences in wealth and health status.
The new brain data largely aligns with the results of earlier work.
Reflecting on the parallel between a visually six-year-younger brain and delayed onset of dementia, Amoruso said the similarity is striking.
“This is consistent with previous findings from other research groups, which suggest that bilingual individuals show symptoms of dementia about six years later than monolingual individuals,” said Amoruso.
The team’s work does not stop here. They now plan to run the same test on individuals with Alzheimer’s disease and other conditions where brain resilience is most critical.
The group also intends to investigate whether speaking two closely related languages simultaneously protects the brain more effectively, requiring sharper mental control than mixing completely different languages.
Researchers caution that this study cannot prove that language itself is the cause, since habits such as physical exercise and an active social life might also contribute. Their group accounted for age, sex, and education, but this list does not cover all the factors that could influence brain function.
One way scientists explain this pattern is through cognitive reserve, the brain’s ability to continue functioning normally even when damage builds up silently. This idea arose from cases where people remained mentally sharp despite clear signs of brain disease.
Being able to speak multiple languages may help strengthen that reserve. Constantly switching between languages and identifying inappropriate words serves as a daily workout for the brain.
Earlier studies suggest that such lifelong efforts help bilingual people retain their skills longer. For now, the practical takeaway is simple. A brain that looks 13 years younger does not guarantee 13 extra years of life.
Instead, it means that its activity more closely resembles that of a younger person’s brain, which could lead to longer and clearer thinking. What was once a controversial idea is now backed by detailed brain data. The analysis of brain clocks shows that for each individual, a long-term shift between languages leaves a measurable mark on how young the brain appears.
Few brain-healthy habits bring as much enjoyment and cost as little as learning another language. This study shows that schools and ordinary learners can benefit from picking up another language at almost any age. The greatest gains likely go to those who start using multiple languages at a young age and continue doing so throughout their lives.
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