Learning a second language is often framed as a social asset. It makes you more marketable, eavesdropping easier, and travel less stressful. But new data suggests there is a biological payoff that extends well into old age. A study published in the Journal of Alzheimer’s Disease in September 2019 points to a tangible link between multilingualism and a reduced risk of developing dementia.
The research, led by University of Waterloo associate professor Dr. Suzanne Tyas, didn’t rely on a random sample of the general population. Instead, it analyzed data from 325 Roman Catholic nuns belonging to the School Sisters of Notre Dame order in the United States. The numbers are stark. Among the nuns who spoke only one language, 31 percent developed dementia. For those who spoke four or more languages proficiently, the rate dropped to just 6 percent.
Why nuns? The case for controlled variables
Looking at religious sisters might seem like an odd choice for a medical study, but it is actually a major scientific advantage. The “Nun Study” began in 1986 and has tracked nearly 700 sisters over time. Because these women shared similar adult lifestyles, researchers could isolate the effect of language without the noise of varying income, social support, marital status, or health access.
In the general population, these factors fluctuate wildly. A multilingual person might also be wealthier, more active, or have better access to healthcare. Those variables usually muddy the water. In the Nun Study, those confounding factors are held constant. This allows scientists to look directly at how cognitive and linguistic abilities factor into Alzheimer’s and other dementia risks, including the role of neuronal hypertrophy, an increase in certain nerve cells in the brain.
“So, in the Nun Study, we have a greater ability to focus on multilingualism without it being influenced by all these other factors that usually vary from person to person during adulthood and that can weaken other studies.” – Dr. Suzanne Tyas
The “use it or lose it” principle
Why would speaking multiple languages help? The brain has to work harder when switching between languages. It requires cognitive flexibility. Tyas compares it to physical exercise for the body. Multilinguals get extra mental exercise that keeps their brains in better shape than monolingual peers.
This aligns with established advice to remain cognitively active to prevent dementia. The brain follows a “use it or lose it” rule. However, there is a nuance. It is possible that people who speak multiple languages have brains structured differently, making them naturally more resilient to dementia. We cannot definitively say if the practice of speaking multiple languages causes the protection or if inherent differences in these individuals are the real cause. Conducting a study where one group learns a new language and another does not, then following them for decades, is nearly impossible to execute.
Writing might be the better bet
Here is where the findings get interesting. The researchers didn’t just look at speech. They examined autobiographical essays the nuns wrote as young adults, decades before taking vows. They analyzed structure, idea density, grammatical complexity, and content.
The result? Written language ability had a stronger protective effect on dementia than multilingualism.
This is a significant shift in perspective. Previous studies often looked at multilingualism in isolation. By comparing it against other measures of language ability, the study suggests that exercising language skills in other ways, like complex writing, may be just as helpful for reducing dementia risk.
Dementia is more than Alzheimer’s
It is common to use “Alzheimer’s” and “dementia” interchangeably, but they are not the same. Alzheimer’s is just one of more than 400 types of dementia. Vascular dementia is another common form. Understanding this distinction matters because the prevention strategies, while overlapping, target different underlying mechanisms.
What if you only speak one language?
If you are not fluent in four languages, do not panic. Multilingualism is only one part of a broader prevention strategy. Tyas notes that dementia is more preventable than many people realize.
Several health choices offer protection:
– Engaging in lots of physical and mental activity
– Maintaining a strong social network
– Eating well
– Controlling health conditions such as high blood pressure
You do not need to learn Mandarin by Friday to protect your brain. You just need to keep using it. Whether that is through learning a new language, writing complex essays, or staying physically and socially active, the goal is the same: keep the brain engaged. The data suggests that doing so can make a real difference in how your brain ages.
