Bilingualism may slow the progression of age-related brain changes
Medical advances lead to a gradual increase in average life expectancy. However, this comes at a price, as the number of cases of dementia and other neurodegenerative diseases increases with age. Researchers from HSE University (Russia) and Northumbria University (UK) have found that bilingualism can slow down and attenuate the progression of age-related changes in the human brain. The study was published in Frontiers in Psychology.
The human brain begins to deteriorate with age: overall information processing speed decreases, short-term and episodic memory deteriorates, and control of linguistic, executive, and visuospatial skills decreases. This process is called “cognitive aging”. At the neuronal level, it manifests as anatomical changes in gray and white matter in specific regions of the brain.
However, the rate at which aging occurs varies and depends on a person’s cognitive reserve, the ability of the brain to cope with the effects of age-related brain damage, and to maintain peak performance. This reserve builds up over a person’s lifetime as the brain strengthens neural networks in response to various external stimuli. The more complex the neural networks, the greater a person’s cognitive reserve and the milder the age-related changes will be. It is already proven that cognitive reserve is influenced by physical exercise, nutrition, career, leisure habits, level of education, socio-economic status and several other factors.
A team of scientists from HSE University (Russia) and Northumbria University (UK) decided to study the effect of bilingualism on the brain functioning of older people and its link with other aspects of cognitive reserve.
The researchers conducted an experiment with 63 adults aged 60 or older. The participants were in good health and had no history of psychiatric or neurodegenerative disorders. Study entry requirements included at least partial knowledge of a second language (“bilingualism” in this case referring to the ability to speak two languages, regardless of fluency). Prior to the experiment, all participants completed a questionnaire that explored their cognitive reserve (including questions on marital status, level of education, occupation, social relationships, sports activities, etc.) The participants were also asked how long they had known a second language, how often and where they used it, and how fluent they were in that language.
Participants were presented with a ‘companion task’, which is traditionally used to measure inhibitory executive control. In the task, participants see a row of five arrows; the central “target” arrow is the key stimulus. The arrows on either side of the central arrow (the ‘flankers’) can point in the same direction as the key stimulus (congruent), the opposite direction (incongruent), or they can be replaced by other objects (such as squares). Participants were asked to indicate the direction of the central target, and to do so as quickly as possible.
In an incongruous situation (when the target and the side arrows are pointing in different directions), it is usually more difficult for a person to concentrate and give the correct answer. However, bilingualism showed a facilitating effect on the task. The longer people had studied a second language and the more fluently they spoke, the better their results in the experiment. It should be noted that the level of language skills of the subjects played a more important role than the duration of learning a second language. The researchers explain this result by noting that bilingual speakers constantly face similar conflicts in everyday life, in which they have to make choices and switch between two language systems.
Unlike other factors that shape cognitive reserve, bilingualism is unique in that it is constantly present in our lives. We can pick up and drop physical exercise, go on one diet or another, change jobs, but the language stays with us all the time. We communicate, watch movies and read books, and language centers are constantly working in our minds. We witnessed an interesting phenomenon in this experiment: with a high level of language proficiency, the correlation between successful conflict resolution and other components of cognitive reserve disappeared. This suggests that the benefits of bilingualism on cognitive reserve may be greater than those of other known factors.
Federico Gallo, Junior Researcher, University Institute of Cognitive Neurosciences HSE
Fluency in two or more languages improves brain function not only in healthy people, but also in people with various neurodegenerative disorders (dementia, Alzheimer’s, Parkinson’s disease, stroke). In another article published in Frontiers in Human Neuroscience, Federico Gallo and his colleagues provide an overview of the latest research on bilingualism and aging. Data suggests that active bilinguals are diagnosed with neurodegenerative diseases 5-7 years later than monolingual speakers. Scientists believe that bilingualism not only improves executive brain functioning, but also episodic, working and semantic memory, and even increases overall fluid intelligence.
“Today, there are no truly effective drugs to prevent or slow down brain aging. Huge financial resources are needed to develop pharmaceutical treatments. Therefore, finding and researching alternative, non-drug ways to slow cognitive aging should become a scientific priority. In the long term, we plan to study how the benefits of bilingualism on aging may vary across language pairs,” says Federico Gallo.
Gallo, F. et al. (2022) Add bilingualism to the mix: L2 proficiency modulates the effect of cognitive reserve proxies on executive performance in healthy aging. Frontiers in psychology. doi.org/10.3389/fpsyg.2022.780261.