Can speaking multiple languages keep you sharp?

You might be surprised to learn that speaking more than one language helps keep our thinking skills healthy in later life. As part of our Staying Sharp series, Dr Thomas Bak of the University of Edinburgh tells us more.

Languages and later life

For many people, the term 'bilingual' brings to mind a baby listening to his or her father and mother speaking two different languages and ending up speaking both of them like a native speaker. However, for millions of people across the world, this definition is much too narrow. This is because they might have learned their second or other languages later in life and can communicate in them without reaching native-like proficiency.

For this reason, we use a broader definition in research. We use 'multilingualism', defined as the ability to communicate in more than one language, with 'bilingualism' as a subcategory involving two languages. Together with the broadening of the definition came a growing interest in the possible effects of multilingualism on thinking skills in later life.

Learning languages looks promising

So far, results of research in this area look encouraging. Bilingualism and multilingualism have been linked to better performance on different tests of thinking skills, including tests used for screening for dementia. People who are bilingual develop dementia 4-5 years later than people who speak one language only, and are twice as likely to recover their cognitive abilities after a stroke.

Even short periods of intensive language learning can produce measurable positive effects on cognitive abilities and these persist in people who continue to practise their new language for 5 hours or more per week.

Which way round?

Why should this be? The research is saying that learning languages helps keep us brighter as we age. But could it be that what we are seeing is a case of 'reverse causality' (a 'chicken and egg situation') - that is, that it’s not learning languages that makes people brighter but that people who were brighter in the first place are more likely to learn languages?

Studies with the Lothian Birth Cohort 1936 (the people participating in the Age UK-funded Disconnected Mind research project) provide invaluable insights into this question because we have measures of the intelligence of the Cohort members at age 11.

Two studies that analysed their data have demonstrated that those who learned languages after age 11 performed better on tests of their thinking skills in their 70s than expected on the basis of their childhood intelligence. This shows that it is language learning that has the beneficial effect in its own right, independently of how bright people were in childhood.

What's the reason?

What might be the reasons for these findings? In people who are learning a new language, the very challenge and effort connected with it could be the answer. But also, people who already know several languages are practising them without realising it.

Research suggests that multilingual people activate all their languages and then select the relevant one(s) for the task in hand.

It’s thought that such a constant juggling between different sounds, words, concepts, and grammatical and social rules, trains so-called 'executive functions' and so keeps them in shape.

These functions include attention switching, inhibition and monitoring - exactly the thinking skills that often appear to be protected by being bilingual.

What more can we learn?

Many questions still remain open, including:

• Does learning more than two languages produce a cumulative benefit?
• Does it matter whether the languages are similar or completely different?
• Is it better to learn to write a language or is it enough to speak it?
• Do we need to practise languages or is it enough just to know them?
• What is the 'dose-response' curve of language learning, i.e. how much time and effort are necessary to achieve a cognitive effect?

However, based on the current evidence we can say that learning and using different languages seems to exert a positive influence on thinking skills in later life.

Key references

• Bak, T.H., Nissan, J.J., Allerhand, M.M. and Deary, I.J., 2014. Does bilingualism influence cognitive aging?. Annals of neurology, 75(6), pp.959-963.
• Bak, T.H., Long, M.R., Vega-Mendoza, M. and Sorace, A., 2016. Novelty, challenge, and practice: the impact of intensive language learning on attentional functions. PloS one, 11(4), p.e0153485.
• Cox, S.R., Bak, T.H., Allerhand, M., Redmond, P., Starr, J.M., Deary, I.J. and MacPherson, S.E., 2016. Bilingualism, social cognition and executive functions: A tale of chickens and eggs. Neuropsychologia, 91, pp.299-306.
• Bak, T.H. and Alladi, S., 2014. Can being bilingual affect the onset of dementia? Future Neurology, 9(2), pp. 101-103.