Bilingualism on the Brain

Multilingualism, beyond cultural and educational benefits, may have effects on the brain that could improve cognitive function throughout life.

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By Phoebe Buckwalter

Many Stuyvesant students know or are exposed to a second language, and everyone takes a language class for the majority of their high school career. In fact, almost all New York schools have a world language requirement of at least one year. While some may enjoy these classes and others may sleep through them, many wonder why they should learn a new language in the first place. Isn’t English enough? Well, learning a new language has more merits than just impressing your friends and family by cracking out a “bon appétit” over dinner; multilingualism actually has great neurological benefits.

It all starts in the brain, and it starts young. Speech production is controlled by Broca’s area while speech comprehension is controlled by Wernicke’s area, and both make up the perisylvian region of the brain, the part that is responsible for language. While experts estimate that the perisylvian pathways develop continuously throughout childhood and adulthood, the auditory system develops as early as 25 weeks from conception, and from then onward the infant brain experiences detectable activity and blood flow patterns in response to different syllables. Scientists debate the critical period for language—the time when the brain’s development is most susceptible to external stimuli—but they generally agree that it begins in the first few years of life and possibly lasts up until late adolescence. In other words, it’s easier for a child to pick up a first, second, or even third language than it would be for an adult. Many researchers claim that this is because our minds lose their neuroplasticity—the brain’s ability to change and adapt—as we age. An adult loses an estimated five percent of their brain mass per year after the age of 40 due to brain matter shrinkage, neuronal cell death, and less sensitivity between neurons. However, just knowing a second language can help stave off this decline. 

The brain is made up of neurons and is generally separated into two distinct tissues: gray matter and white matter. Gray matter makes up approximately 40 percent of the brain and consists of neuronal cell bodies, the part of the neuron that contains the nucleus and receives information. The other 60 percent is white matter and consists primarily of axons, the long cables that connect the cell bodies and receptors together. Both play a significant role in brain function, the reception and processing of stimuli, and communication. Compared to monolinguals, bilinguals have increased thickness and density in gray matter, as well as increased health and coherence in white matter. A study by King’s College London professor Andrea Mechalli and his team found a positive correlation between gray matter density in the inferior parietal cortex and one’s proficiency in a second language. They found that this area with increased gray matter volume correlated almost exactly with the region responsible for second-language acquisition. This is strong evidence that bilingualism is directly responsible for this increase in gray matter. On average, bilinguals are less susceptible to neurodegeneration. A potential reason for this is that the increased stimulation of learning and using a second language leads to both the development of more nerve cells and the strengthening of existing neuronal connections.

The strength of synaptic connections between neurons is primarily increased by a process known as long-term potentiation (LTP). When a signal repeatedly moves across the synaptic cleft—the space between the transmitters of one neuron and the receiver of the next—the receiving neuron becomes more sensitive to the signal. Constant exposure to and use of another language repeatedly stimulates the neurons, leading to increased synaptic strength. This not only improves one’s language skills but also increases the impact of all signals traveling through the synapses, enhancing memory and attention. It also helps maintain improved strength—LTP suppression due to disuse is one of the most common causes of decreasing synaptic sensitivity, which contributes to brain mass loss. 

The most significant effect of multilingualism, however, is its potential to delay the onset of Alzheimer’s disease (AD). AD is a common type of dementia where patients experience memory loss and cognitive deterioration as a result of mass neuron death in the brain. The onset of AD in bilinguals delays by almost five years compared to their monolingual counterparts. This may be due to multilingual patients having a greater cognitive reserve from their increased brain matter volume. This means that it would take a longer time for a multilingual patient to lose a similar amount of brain mass compared to a monolingual and see a similar cognitive decline. A similar reasoning could be used to justify arguments about bilinguals’ improved cognitive recovery after a stroke or other neurodegenerative diseases.

While there are still debates over the correlation versus the causality of multilingualism on the brain, there is a massive body of empirical evidence that suggests multilingualism’s positive neurological effects. However, besides the neuroscience of it all, learning a new language can expand one’s mind in a variety of ways, such as creating a connection to another culture, people, or time. Maybe next time, try to pay attention in your language class and absorb the joys of learning a new language. Your mind might just thank you in the long run.