I was recently introduced to a friend’s five-year-old daughter, and I’m already living in her shadow. She is being raised with not one, not two, but three languages. I began calculating how soon this child would know more total vocabulary than I do, and realized it’s probably already happened.

Nothing makes you feel intellectually insecure like finding out that a child might be smarter than you. But I found some small relief in talking with psychologist and noted researcher Ellen Bialystock, who studies the effects of language on the brain.

“Look, I will never say that bilingual kids are smarter,” says Bialystock, from York University in Toronto, Canada, after I repeatedly peppered her with the question. “That’s something you can never say.”

Phew!

My relief, however, was cut short as Bialystock continued:

“What we can say is that some of the cognitive processes that are part of intelligence are more developed in bilinguals.”

So what, exactly, does that mean?

Brain Changer

A common view before the 1960s was that teaching a kid more than one language at a young age was confusing. Behavioral studies at the time posited that young minds weren’t developed enough to handle so much information, and that bilingualism was disorienting for children. Since then, countless studies have shown that young brains are a lot more adaptable than old school social scientists gave them credit for being. Learning multiple languages won’t confuse a child, or an adult learner: bilingualism actually reshapes the brain.

(A quick note here: when I refer to “bilingualism,” I’m not talking about taking a couple of Spanish classes so you can order a torta with confidence; most of the cognitive benefits I’m about to point out only happen for people who are certifiably bilingual -- people who pass fluency tests, things like that.)

In one study carried out by Cathy Price, a neuroimaging researcher at University College London, it was discovered that bilinguals had more gray matter in their posterior supramarginal gyrus, a long name for the ridged part of the brain that researchers have associated with vocabulary acquisition.

“When you learn more language, your posterior supramarginal gyrus will get a workout, and be stimulated to grow,” says Price. “When you look at the images, there is more gray matter density with more than one language spoken.” The image below is just one of the brain scans Price's team took of a bilingual brain; it shows the same brain, from three different angles, with the yellow spot identifying the area of the brain where they've seen thickening:

Since gray matter makes up a good portion of the nerve cells within the brain, the more gray matter in that particular gyrus, the faster and more accurately your brain will perform certain tasks. For example, there is evidence that bilingual brains are better at doing tasks where conflicting information has to be processed. In one study, Ellen Bialystok subjected a group of 5 year olds -- some bilingual, some monolingual -- to something called "Simon Tests," which are used to determine how quickly people can respond to confusing stimulus. For example, you might be asked to push a button with your right hand that triggers a light on the left side of your field of view - things like that which feel unnatural. The bilinguals, on the whole, were much better at the tests, which suggests they are much better at sorting out conflicting information.

Since the bilingual brain is adept at suppressing the language that isn’t being used in a given moment, it has experience inhibiting unhelpful information and promoting important stuff. There are lots of benefits to this -- one study found that bilinguals were more able to filter out ambient noise. Speaking two languages means you feel less overwhelmed when trying to order in a busy restaurant, and makes you more capable of talking to someone on a crowded subway.

Price is quick to point out that, at best, any benefits are minimal. Bilinguals are only a few milliseconds faster at sorting information, but, hey, that adds up!

“Bilingualism is an experience,” says Bialystock, and just like any other exercise (e.g., dancing, knitting, using sign language) it re-wires the brain, forming new neurons and new connections.

Preventative medicine

While many contemporary studies have linked bilingualism with a better-performing brain, more recently, a few researchers have begun exploring the question of whether language proficiency affects disease outcomes -- does bilingualism, in other words, help stave off certain illnesses? Bialystok has studied people suffering from dementia and she believes that the healthier bilingual brain actually weathers the ravages of aging better than a monolingual one.

In one experiment published in 2012, Bialystock examined the brain scans of 40 patients diagnosed with probable Alzheimer’s disease. “For our test subjects, we had people with the same level of disease, at exactly the same age,” says Bialystok. They all showed approximately the same symptoms. Their brains, therefore, should look pretty much the same. But what Bialystok found was surprising.

Traditionally, the brain of a person with Alzheimer’s atrophies as neurons die: the brain’s outer layer begins to shrink, and the hippocampus withers. When Bialystok compared the brains of 40 patients, she found that the brains of the bilinguals in the study showed twice as much atrophy as the monolinguals. But despite having far more diseased brains, they had performed as well on cognitive tests as the monolinguals with less diseased brains.

What? With more atrophy, you’d expect the disease to be further along -- you'd expect those patients to have more problems functioning day-to-day. But for the bilinguals, it wasn’t, and they didn’t. Bialystok has undertaken a couple of similar studies in the last few years, and every time, she’s found the same result: language multiplicity appears to hold off the effects of dementia. In one examination of 211 probable Alzheimer’s patients, the effect was so great, she found that the bilingual patients had reported the onset of symptoms 5.1 years later than the monolingual ones.

Bialystock is the first to say that, while her studies are promising, they aren’t definitive. “There are lots of questions here,” Bialystock says. “Like, why would bilingualism fight Alzheimer’s anyway?” But she believes it has something to do with how language re-wires us.

Who's smarter?

That's all good news for that five year old, though I still wanted to know if she was smarter than me.

The closest I could come to an objective measurement was IQ scores...and well, I won't get into the caveats and thorniness of using IQ to measure anything, let alone how smart you are. Quite a few studies explicitly draw a parallel between bilingualism and a high IQ score, but researchers are quick to point out that such a relationship is not perfect.

“One of the IQ tests is a vocabulary test, and in general, we might expect bilinguals to do slightly worse on a [vocabulary] test in one language than if it was their only language,” says Price. 

The reason for this vocab disparity is that bilinguals learn and use each language “for different purposes, in different domains of life,” according to a book by french linguist Francois Grosjean. A kid might learn and use different languages for home and school, which means that, because of context, they won’t get the full vocabulary of either place. Kind of a, “Jack of all trades, a master of none” scenario.

“Bilinguals have a larger vocabulary, since they speak two languages,” says Price, “but they might know fewer words within a language.” 

It seems nit-picky to me to say that a bilingual individual might be at a disadvantage because they don’t speak as many words in each of their languages, and I think it’s fair to say that the cognitive benefits of bilingualism probably outweigh the slight disadvantage they face on a test that is often discredited. Which again is good news for the multilinguals, but not for me and my monolingual ego. And it’s going to be hard to make up for lost time: researchers show that it’s tougher to fluently learn a second or third or fourth language as you age, meaning that adult learners might have a hard time getting the sweet, sweet cognitive advantages that bilingual children enjoy. Even if I start now, I may never catch that kid. Or this one:

A special thanks to Vladimir Sanchez from San Francisco, for sending us Labbers the question about bilingualism that got us thinking in the first place; and to Judy Willis, a neuroscientist/teacher/advocate for bilingual education, for pointing me in the right direction as I set out to report this piece. She blogs about bilingualism for Psychology Today.