Science

the relationship between Alzheimer & Down

Dementia in disguise

Seventy percent of people with Down syndrome get Alzheimer’s disease. How do you diagnose this disease in people who already have trouble learning and remembering things?
By Christien Boomsma / Translation by Sarah van Steenderen / Photo by Jaap Dekker

Her name was Gea. He had known her since he was a baby. She worked at the Tearoom, a tea shop near de Zalkerveer, which served as a daycare project for people with mental disabilities. She was close to his mother and next to his parents, she was the person who held him most. She would comfort him when he cried. Kept people who shouldn’t from picking him up.

She also had Down syndrome.

‘The ferry and the Tearoom were run by my parents’, says neuroscientist Alain Dekker. ‘We lived in the old ferry cottage. The clients worked in the Tearoom next door, and they were practically family. On my birthday, they would barge into my bedroom to sing to me.’

Increasingly fearful

Even when Dekker started studying in Groningen, he couldn’t stay away. Every weekend, every vacation, he spent working with ‘his people’. Even now, he visits the Tearoom once a month.

On my birthday, they would barge into my bedroom to sing to me

But Gea had started to change. Sometimes she would freeze in the middle of service and start yelling. She became increasingly fearful. Her behaviour started influencing the other clients so much that she had to be transferred to a different location.

‘I saw her again years later, at a Christmas market in IJsselmuiden’, says Dekker. ‘She was completely out of it. She had a glassy look in her eyes. She saw me, but I’m not sure she recognised me.’

Six months later, he got her obituary in the mail.

Chromosome 21

Neither Dekker, his parents, nor Gea’s therapist had realised what had been going on with Gea. Until Dekker, by then a master student of neuroscience, took a class by professor Peter De Deyn, who talked about behavioural changes in people with dementia. Almost as an aside, De Deyn mentioned that at least seventy percent of people with Down syndrome gets Alzheimer’s disease. ‘While only eleven percent of the rest of people get it.’

That’s when the penny dropped. ‘That’s what happened to Gea. I was so overcome!’

The cause of all this misery is chromosome 21. This chromosome has a gene that produces a sticky amyloid protein. This amyloid accumulates in the brain and damages it. This damage can then lead to dementia. Normally, this doesn’t lead to problems until people are quite old. However, people with Down syndrome have three copies of chromosome 21. And three chromosomes make more sticky protein than two. So much so, that the brain of a forty-year-old person with Down syndrome looks like an Alzheimer brain.

Not particularly sexy

As soon as class had ended, Dekker chased after De Deyn. What was the reason that almost every Down brain becomes an Alzheimer brain, but not everyone suffers symptoms? Is it possible to predict who will get symptoms and who won’t? Could De Deyn tell him anything else about the relationship between dementia and Down?

Unfortunately, he couldn’t. There has been relatively little research into the connection. After all, research into people with Down syndrome is not particularly sexy. But after fifteen minutes of walking and talking, De Deyn and Dekker reached a conclusion: ‘We’re going to research it.’

Their environment thinks the behavioural changes are due to age

Now, four years later, Dekker is getting his PhD for his research in the relationship between Down and dementia. He focused in the first place on actually recognising the problem, something which Gea could have benefited from.

This is not as easy as one might think. The brain of a person with Down syndrome already contains those protein accumulations present in Alzheimer, so that wouldn’t serve as an indicator. The tests that are normally used to recognise dementia, which focus on knowledge and memory, don’t take into account that people with Down syndrome have trouble in exactly those areas.

Gradually

So Dekker decided to focus on behaviour. Changes in behaviour in people with Down often go unnoticed. ‘That’s because these changes occur gradually’, says Dekker. ‘This means their environment changes with them. Either that, or they think the behavioural changes are due to age or the mental disability in the first place.’

Dekker talked to health care institutes from all over Europe and collected 83 different ‘behaviours’, which he incorporated into a questionnaire, with entries such as ‘The clients is/seems to be afraid to be left alone’ or ‘The client shows a lack of initiative’. The person responsible for filling out the list then has to compare the last six months to the time period before those months. ‘It forces people to take stop and think about how someone’s behaviour has changed over the past few months. Only then do they clearly see that someone has become more apathetic, fearful, or aggressive.’

Dekker applied his questionnaire to three hundred people with Down syndrome, divided into three groups: one with Alzheimer’s disease, one without, and one with a question mark. It is the largest study among people with Down syndrome in the world.

Alarm bells

Dekker is ‘incredibly proud’ that so many people cooperated in the study, he says. And the list works. In the ‘Alzheimer group’, six out of ten patients had clearly become more apathetic. He also determined an increase in fear and depression. But the ‘question mark group’ also showed symptoms. Enough to set off alarm bells, he says. And that was exactly what he wanted to find out.

It’s manageable when you know what’s going on

Because although you can’t cure Alzheimer, you can help people suffering from it. ‘Their behaviour is the most taxing’, Dekker says. ‘But it’s manageable when you know what’s going on. This can lead to a better understanding, and making changes to their environment can really help. For people who are really fearful, for example, a night light can make a lot of difference.’

But one important question remains. When Dekker started his research, he had also hoped to solve that other riddle: why some people develop symptoms and others don’t. And it almost looked as though he would succeed.

Brain fluid

‘Dementia is a problem in the brain. The protein accumulations damage the neurotransmitters in the brain’, Dekker explains. ‘So we wanted to know if we could find changes in the neurotransmitters.’

When he studied the blood serum of people with Down and dementia, it almost looked as though he’d struck gold. The level of MHPG, a degradation product of the neurotransmitter norepinephrine, had gone down considerably. But even more interestingly, this also happened in people who would probably not start suffering from dementia for another five years. ‘And that would mean we might be able to develop a test that your general practitioner could administer’, he says.

There is something there but we just don’t know what

Unfortunately, science needs experiments and verification. And in a follow-up study, where Dekker looked at the MHPG levels in brain fluids and brain tissue of patients, no clear differences were found.

MHPG levels

Why? Dekker hasn’t been able to put his finger on it. The second study was small, using only the brain tissue of twenty people, but getting the required materials was a hell of a job. While there are often hundreds of samples available from regular people, there aren’t as many from people with Down syndrome. Another problem: for his first study, he didn’t have access to any brain fluids, and in his second, he had no serum. ‘We’re not sure yet why we can’t see it anymore’, he says.

For now, he is focusing on his PhD ceremony, which will take place on Wednesday, 15 November. At the ceremony, twelve clients from Tearoom Zalkerveer will also be present. Next, he will spend another year refining his questionnaire and developing an app that should make using the list easier.

And after that? He hopes to secure more financing and to attract more attention to this particular group of people. And who knows, maybe he’ll find a way to continue looking for MHPG levels. Because he can’t let it go. ‘There is something there’, he says. ‘We just don’t know what.’

Nederlands

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