Speaking two languages may slow brain aging

Bilingualism has hit the headlines this week with the news that learning a second language might bring cognitive benefits in later life – even when that second language is acquired in adulthood.

The study was led by Dr. Thomas Bak at the University of Edinburgh, whose other work suggests that bilingualism might delay the onset of dementia. The current study looked at tests such as verbal fluency, in 835 native English-speakers aged 70 or older. Of these participants, 195 people had learnt a second language before 18, and 65 had learnt a second language after 18. The researchers compared people’s scores on the tests aged 70 with their IQ scores age 11.

The results showed that people who spoke a second language performed better on the tests than would be predicted from their early IQ results, relative to their monolingual peers. There were no differences between early versus late second language learners. In other words, learning a second language may slow brain aging.

These findings are important because they can help us answer the question of cause and effect. There are two possible reasons why bilinguals might show an advantage on cognitive tests. The first possibility is that people who have better cognitive ability to begin with are more likely to go on and learn another language. The second possibility is that learning a second language improves people’s cognitive ability. This study suggests that the second possibility is more likely – bilinguals did better on the tests than their childhood IQ scores would have predicted.

The fact that learning a language in adulthood seems to give the same advantage as learning a language in childhood is a highly relevant in the UK, where many people think that bilingualism only refers to people who grew up speaking two languages equally well. In fact, the advantages of bilingualism are relevant to anyone who uses a second language, whether they learnt it in the family, at school, or later on in the workplace. As Dr. Thomas Bak says, “Millions of people around the world acquire their second language later in life. Our study shows that bilingualism, even when acquired in adulthood, may benefit the aging brain.”

The study has been widely reported in the media including articles on the BBC health section, as well as daily news sites such as the Telegraph, the Times of India , and the Huffington Post , and science-specific sites such as Medical News Today, Science Daily, and
NHS Choices.

The full study “Does bilingualism influence cognitive aging?” was published online in the Annals of Neurology, on 2nd June 2014.

UofE study on Bilingualism and Dementia takes the media by storm


A study about bilingualism and dementia led by the University of Edinburgh’s own Thomas Bak, in partnership with Nizam’s Institute of Medical Sciences in Hyderabad, India has taken the media by storm.

It has been reviewed and reported in over a hundred media sources, including national networks such as the BBC and NBC news, CBS and SPS, dailies such as the Huffington Post and the Times of India and the Japan Times  and health web platforms such as the NHS or Health24, or scientific publications such as the New ScientistScienceDaily and the National Geographic.

The study, published in the American magazine Neurology, surveyed over 600 patients and found that on average, bilingual patients developed dementia 4.5 years later than monolingual ones, irrespective of educational achievement, sex, profession or lifestyle. This is the first study of its kind to include illiterate subjects, showing that bilingualism is a health asset for anyone. The study was even reported by the Daily Mail, which reads that being bilingual could be better than any currently available medication as a cure for dementia.

It is encouraging to see how widely this publication has been received, we hope that it will encourage parents to protect their linguistic heritage and teach their children to do the same.

Understanding the enhanced cognitive control in bilinguals

From previous studies, we have seen that bilinguals tend to outperform monolinguals in some tasks requiring subjects to switch between two stimuli; these are known as Cognitive Control tasks. The bilinguals that have taken part in many of these studies are people who speak two languages under the same modality for instance, two spoken languages (unimodal bilinguals). But what happens when a person knows two languages in different modalities, like in the case of bimodal bilinguals, who know a spoken language and a sign language? On this study, there were three groups of participants: unimodal bilinguals, bimodal bilinguals, and people who only knew one language (monolinguals).  Interestingly, all three groups performed equally well in tasks involving ignoring one stimulus in order to respond to another, but the only difference was that unimodal bilinguals were faster than both bimodal bilinguals and even monolinguals. As the authors point out,  bimodal bilinguals can, in fact, produce words simultaneously (one signed, one spoken), whereas unimodal bilinguals have to suppress one language when speaking the other one, because it is impossible to say two words at the same time. Therefore, the faster responses for the unimodal bilinguals could be accounted for by the fact that they are better ‘trained’ at suppressing one language when speaking the other one.

This is a summary of the following published article:

The source of enhanced cognitive control in bilinguals: evidence from bimodal bilinguals. by Emmorey, K., Luk, G., Pyers, J. & Bialystok, E. (2008). Psychological Science 19: 1201-1206.

Bilingual children with different languages and cultures perform better than monolinguals at executive control tasks


One of the cognitive domains that have been studied for bilingual advantages is ‘Executive Control’. Generally speaking, this function refers to a set of processes that have to do, for instance, with attending to one stimulus while suppressing another one. Because bilinguals use similar processes when they have to switch between the languages they speak, it has been thought that they may perform somehow more efficiently at tasks requiring such abilities, even in tasks that do not have to do with language. This study looked at the possible advantage on Executive Control in bilingual children with different language and culture backgrounds: bilingual children in Canada and bilingual children in India. Performance on different Executive Control tasks of these two groups was compared to a monolingual group of Canadian children. The authors showed that both bilingual groups performed similarly to each other and moreover, they were better than the monolingual group in tasks involving Executive Control abilities. These findings show that the specific bilingual advantages looked at in this study occur irrespective of a child’s language and cultural background.  Read full article here or here.

Early bilingualism enhances mechanisms of false-belief reasoning

Children below the age of 4 have difficulty understanding that other people can hold beliefs that do not correspond to their own beliefs, or to reality (these are called “false beliefs”). Different reasons for this difficulty have been proposed. Some suggest it could be lack of experience with real-life situations in which beliefs mismatch. Others think children understand the concept of false beliefs, but they find it difficult to suppress their own belief, so that they give the wrong answer when questioned about the beliefs of others. This study compared monolingual and bilingual 3-year-olds who came from similar socio-economic backgrounds, had similar intelligence, and similar linguistic abilities. Despite these similarities, bilinguals performed better than monolinguals: they were more likely to respond correctly when asked to predict what a cartoon character would do given its (false) belief; they were less likely to respond on the basis of their own (true) belief. Bilinguals’ advantage was similar when the character’s false belief was caused by ignorance (for example, not being present when an object was moved from one location to another) or lack of understanding (for example, not speaking the bilingual child’s other language). The author concluded that bilinguals’ advantage was probably a result of greater practice with inhibition of the wrong response, due to the fact that they constantly have to inhibit one of their languages when speaking in the other.

This is a summary of the following published article:

Early bilingualism enhances mechanisms of false-belief reasoning by A M Kovacs (2009). Developmental Science 12(1), 48-54

How do infants learn to associate a new word to the correct object?

One way monolingual children do this is by using the disambiguation principle: if they are confronted with two objects, one new and one familiar, and they hear a new word, they will tend to associate it to the new object (because they already know the name for the familiar object).

This study compared 17- and 18-month-old infants from monolingual, bilingual, and trilingual family backgrounds. Infants’ use of the disambiguation principle was inferred from their tendency to look more at the new object after hearing a new word than after hearing a familiar word. The results showed that trilingual infants did not follow the disambiguation principle, probably because they know that the same object can take different names in their different languages. Bilingual children behaved more like monolinguals, although they followed the disambiguation principle less consistently.

This is a summary of the following published article: “Monolingual, bilingual, trilingual: infants’ language experience influences the development of a word-learning heuristic” by Krista Byers-Heinlein and Janet F. Werker (2009). Developmental Science, 12(5), 815-823.