What do we know about Parkinson's disease?

And how that informs treatments of the condition...
21 November 2023

Interview with 

Claire Bale, Parkinson's UK


The hands of an elderly couple.


So, what do we know - and not know - about this disease? Chris Smith spoke to Claire Bale, associate director of research at Parkinson’s UK…

Claire - Parkinson's is a progressive neurological disorder and that means it affects the brain, primarily. We know that, in people with Parkinson's, they don't have enough of a chemical called dopamine inside their brains. Particular brain cells that make dopamine - a chemical that's used to do many things in the brain - start to die for some reason and we don't know why that is. And because people with Parkinson's don't have enough dopamine, it means that they can't get the messages that they need to around the brain that help to coordinate movement. And that's why the symptoms of Parkinson's include many movement difficulties. So people might shake, have slow shuffling walking, stiffness, slowness of movement, very small handwriting, things like this can be some of the really obvious signs of Parkinson's.

Chris - What tends to be the first things people notice that, when they look back they say, 'I think that's how it began.'

Claire - It's a really good question because we now believe that, by the time obvious symptoms of Parkinson's, so the things that I've mentioned like slow stiff movement or a shake in a hand, for example, once those emerge, we actually believe up to 70% of the brain cells that make dopamine have already died. So we think Parkinson's may start a long while before those symptoms emerge. And some of the very early symptoms can include things that are not movement related, things like low mood or depression, anxiety, sleep problems, constipation, loss of sense of smell. So although we think about Parkinson's as being primarily all about movement, it's actually much more complicated than that. We're still learning about all the different things that can be affected in Parkinson's and how they might emerge. But some of those symptoms can be up to 10 years or even longer before a diagnosis is made.

Chris - Who tends to get it? More men than women? Certain ethnicities? Do we have a picture?

Claire - It's more common in men. Probably about 55% of people with Parkinson's are men compared to women. It's usually older people. So most people who get it are diagnosed after the age of 60, but it can affect anyone at any age. I've met people in my job who've been diagnosed in their twenties or thirties, so it can really affect anyone. In terms of ethnicity, we don't have enough research. Most research has been done in Western populations in Europe and America, so we have a bit of a skewed view, but we do know that it affects people all over the world. We've been involved in research done in Africa, for example, and there are people living in Africa with Parkinson's, although they often don't even know they have Parkinson's because there isn't the same level of care or awareness of the condition.

Chris - And I suppose if you have a disease that generally affects older people and you have a population that is younger for various reasons, it may not be as manifest as it would in a an older population like the UK?

Claire - Yes, absolutely. So in the UK we think there are about 153,000 people living with Parkinson's right now, but we expect that number to go up as our population continues to age. We think there might be over 170,000 by 2030, I think. It's definitely a condition that's on the increase, not just in the UK but around the world, partially due to the ageing population. But there may also be other factors that are driving that increase, such as environmental factors that might be involved in causing it like pollution or exposure to chemicals.

Chris - And is there anything we can do to identify people who might be at risk? Or just reduce everyone's risk? Or both?

Claire - Yes, really good question. We're actually funding research right now to try and find best ways to predict Parkinson's and identify people who are at more risk. So if you've got Parkinson's in your family, then you are at slightly higher risk than someone who doesn't. Age is the main risk factor. We all get more likely to get it as we get older. If you've worked with pesticides for example, not many people do but, if you have, that can increase your risk. There are also things that can decrease risk: the most surprising one being smoking. People who smoke, or used to smoke, are less likely to get Parkinson's than people who don't smoke. Most of the time we think about smoking as having no positive effects, but this seems to be one. And also we know that people who exercise, people who have a really healthy diet, are slightly less likely to get Parkinson's, but smoking is one of the strongest protective factors.

Chris - Although cynics say that people who smoke might not live long enough to get Parkinson's disease, but you are, I presume, controlling for that. And we're not advocating that anyone should take up smoking to reduce their risk of Alzheimer's or Parkinson's disease because obviously the risks of everything goes up enormously when you smoke.

Claire - Absolutely, yes. So those studies have controlled for the fact that people who smoke are less likely to live as long. We do not advocate that anyone takes up smoking. But it's interesting and it has triggered quite a lot of research into things like nicotine and the effect it might have on dopamine producing cells in the brain, that kind of thing. So it might be that we can figure out why smoking is protective and then use that knowledge to help us develop new therapies or preventative strategies.

Chris - Speaking of therapies, what can we do if a person's newly diagnosed with Parkinson's disease? How are they managed?

Claire - Really good question. So Parkinson's is primarily treated using medication. So we have a range of medications that essentially work by topping up dopamine inside the brain or pretending to be dopamine inside the brain. So suddenly people who are unable to make enough dopamine themselves with the brain cells that they have, have extra dopamine to play with and that can help iron out the problems that they have with movement. Those medications are very effective, especially in the early stages of the condition. But we don't have any treatments yet that can stop the progressive loss of brain cells that make dopamine. That means that, over time, people's symptoms get worse, but also they need to take more and more medication to top up their dopamine levels. That means they're more at risk of developing side effects. That's why we need to find better treatments for Parkinson's. But, alongside medications, we also know there's lots of other things that are really important, particularly exercise. Exercise is really important for people with Parkinson's in helping to maintain mobility and flexibility, building strength and stamina. We also believe, through research, that exercise might actually have a protective effect. It might be the only thing we have at the moment that can actually slow down the progressive nature of the condition. It can't stop it, but it might be helping to protect people and keep people healthy and well for longer.


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