Merel Keijzer Photo by Reyer Boxem

Teach every senior a new language

A defence against ageing

Merel Keijzer Photo by Reyer Boxem
People who speak more than one language tend to suffer from dementia at a later age and recover from a stroke more quickly. But can language be used as therapy? Merel Keijzer supplied seniors with guitars and a language teacher to find out.
By Christien Boomsma and Mariam Jamureli
1 March om 13:08 uur.
Laatst gewijzigd op 2 March 2022
om 12:16 uur.
March 1 at 13:08 PM.
Last modified on March 2, 2022
at 12:16 PM.

Language, she says, is everywhere, all the time. You can’t switch it off, you can’t decide to just not engage with it. Even if you’re taking a walk on the beach by yourself, or crawling into bed at night, you’re always in conversation with yourself. Even your thoughts, your inner speech, are a form of language.

Everyone learns language. The moment you are born, you learn the meaning of certain sounds. You learn how the order these sounds are in can mean something good, or something bad. You slowly learn the nuances between the sounds. 

‘On top of that, more than half the world’s population is bilingual’, says linguist Merel Keijzer. ‘They speak another language or dialect in addition to their first language.’

She’s always been fascinated by the concept. Sometimes she’ll be on the bus, listening to people who are on the phone. ‘Someone will just effortlessly switch to a different language in the middle of a conversation. Why? Are they talking about something private they don’t want anyone else to hear? Or is it so personal they can only talk about it in their mother tongue?’


She wanted to know what that mechanism was, and what happens in our head when we switch from one language to another. She knows it takes effort. ‘You may not notice it yourself’, Keijzer explains, ‘but research has shown that there’s a delay in your brain when you switch.’ 

It takes just a fraction of a second longer for people to locate the word they need or before they recognise a grammatical construction. It barely has an effect in real time, but it’s a sign that the process isn’t automatic  

If your brain works hard, you stay healthy for longer

It’s no wonder, really. ‘It’s not like German is stored in one part of the brain and Dutch in another’, she says, smiling. ‘It’s all in the same language centre. When you learn something new, it’s automatically in competition with what you already know. It needs to find its own spot.’

A few years ago, Keijzer discovered this kind of mental juggling can lead to some surprising effects. A brain that is constantly working to distinguish between two languages stays young for longer. ‘It’s not that bilingual people live longer’, she explains, ‘but they generally stay healthy for a few more years than monolingual people.’ Bilingual people recover more quickly from a stroke, for example, and are less quick to suffer from dementia. ‘They have larger cognitive reserves. While their brains decline at the same rate as that of others, the decline is more manageable. It makes no difference to their daily lives.’

Later age

Her research mainly focused on people who’d been bilingual their whole lives. But over the past few years, Keijzer has been looking elsewhere. What about people who learn a second language at a later age? Do they still experience the beneficial effects? 

There’s absolutely no reason to think that the elderly wouldn’t be able to learn a language. ‘People can still learn in this stage of their lives, not just forget’, Keijzer emphasises.

She did discover that old people learn differently than young people. If only because they’ve had a lifetime to figure out what they want and don’t want. ‘Some of them didn’t even want to bother learning the grammar, because they knew they couldn’t do it. They wanted to learn enough to be understood.’ 

Another question is whether the effect on the brain is only achieved by learning a language. What about learning to play an instrument? Or how to solve sudoku puzzles? Could language classes be used as therapy, in an effort to combat depression or dementia?

Keijzer has worked hard over the past four years to answer exactly those questions. With the help of her PhD students and an 800,000 euro Vidi grant, she’s come a long way. 


She made use of the research she does in partnership with Lifelines, the long-term epidemiological study that collects the health data of 167,000 residents of the north of the country across three generations. This provided her with information on how bilingualism impacts the cognitive and mental health of people who’ve been bilingual their whole lives. 

Some seniors become more depressed during the experiment

But it’s the intervention methods that are most innovative right now. Keijzer and her PhD students recruited dozens of people between the ages of sixty-five and eight-five, who were either taught English or how to play the guitar over the course of three months. A third group did nothing. That is to say: ‘They were the passive control group. They did meet up, but they didn’t actually learn anything.’

Various PhD students tracked the effects the classes had on the different groups of people. They were divided into those who were perfectly healthy, those who were already experiencing forgetfulness, and seniors suffering from depression.

Initially, the experiment went very well. There were teachers who had been given exact instructions on how to structure the classes. ‘We bought sixty guitars and distributed them’, says Keijzer. ‘The participants were allowed to keep the guitars when the experiment was over.’ The elderly participants loved it.


But then the pandemic happened. While the small classes used to be taught by a clearly enthusiastic teacher, the seniors suddenly had to learn to work with Google Meet. It wasn’t always easy for them. The social aspect, something the test subjects were enjoying, was suddenly missing. 

‘We’ve tried to compensate as much as we could’, says Keijzer. ‘There was always a student assistant present in the digital space an hour beforehand that could help them.’ 

But analysing the data from the experiment also proved to be difficult. How could the researchers distinguish between the effects of Covid and those of the intervention? ‘Some of the elderly participants became more depressed during the experiment’, Keijzer explains. That’s exactly the opposite of what she’d expected. Then again, the circumstances were unique. Who wouldn’t get sad during a lockdown where they couldn’t have any visitors?

We were all about cognition, but the social aspects were important, too

She and her PhD students worked extremely hard to purge the ‘Covid effect’ from their data. Now, approximately a month before her first PhD student Saskia Nijmeijer will finish her thesis focused on seniors with self-reported memory issues, the first results are finally coming in. ‘If we focus on improved cognition and cognitive flexibility, we’ve seen that most participants remained stable over the course of the three-month study’, says Keijzer. ‘At that age, that’s a plus, wouldn’t you say?’ It also turned out that there was barely any difference in the effects of learning a language or learning to play an instrument.  


She’s studied the beneficial effects of language for years. Is she unhappy with these results? 

Keijzer smiles. Not really, she says. First of all, these are only the first results and the other studies, like the one with seniors suffering from depression, haven’t finished yet. Secondly, she’s loved seeing how the seniors got their zest for life back. If learning a language can help with that, so much the better. 

‘When we started, the study was all about cognition’, she says. ‘We wanted to know if we could measure a cognitive effect with an EEG or if we could see it in their behaviour. We were looking for improvement or stabilisation. The language or music lessons were the goal, not the means.’

Slowly but surely, she’s come to see how important the social aspects of the study are. ‘These people have created WhatsApp group chats. They gained new friends. We can focus on the cognitive results all we like, but we shouldn’t lose sight of the bigger picture.’