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Motor Neurone Disease (MND)

Possible causes of MND (including inherited forms of MND)

Most people who develop MND have no family history of the condition, and it is extremely unlikely to develop in other family members. (See below for familial or inherited MND). Little is known about what causes this form of MND. It is thought that MND is caused by a mix of genetic and environmental factors, and several possible factors have been suggested, including exposure to chemicals, fractures and injuries, smoking, military service, and engaging in some sports or high levels of exercise, but research studies have so far failed to find clear conclusive evidence. Probably lots of different factors are involved, and in any one person MND is likely to occur for complex reasons, rather than there being any single cause. Several factors may increase the risk of developing MND or may help to 'trigger' it, but may not be enough in themselves to cause it.

Some people we talked to felt there was little point worrying about what had caused their condition or whether they had done something to cause it. Lots of people asked themselves 'Why me?' but at the same time many felt it was important that people should not blame themselves. Some also pointed out that it would not make any difference to their condition even if they did know what caused it. 

 

Not even the experts know why people get MND. She knows there's no point worrying if she did...

Not even the experts know why people get MND. She knows there's no point worrying if she did...

Age at interview: 39
Sex: Female
Age at diagnosis: 38
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You get angry. You go through the 'why me?' stage, why not anyone else? You get angry, you get annoyed. You think to yourself, 'What have I done that's so bad?' And you're totally illogical. It doesn't, it doesn't hit anyone in particular. It's very indiscriminate the disease, like any other disease, but even though you know that it's illogical to think that way, you do think that way. You know, 'What have I done so wrong?' You go through thinking, 'Was it my lifestyle? Was it food I ate?' But there is no, there's no rhyme nor reason to it. 

And not, not even the experts know why people get MND and they think it might be environmental, they might think there's a genetic factor, but they don't know so. Again the best thing to do, well, from my, in my instance is just to push it to the back of our mind and not think about it. Grieve for the, for the bits that you want to grieve about and then push it to the back and forget about it then. As you say, when it comes to the forefront you get very upset and it's not worth upsetting yourself about. 

Other people I know with MND get very angry and it's the anger that carries them through. Other people research everything that's going on, they need to research everything that, any new medical sciences that are going on and research into MND. I don't bother doing that, I'm too lazy [laugh].

And again I think it takes up far too much of my life. My life's not long enough now to worry about that. It's to concentrate on my family and enjoy myself. And my way of getting through with, as I said some people get angry. Some people get bitter and I, I just make fun [laugh] and joke about it a lot. So that's my way of getting through with my stupid jokes [laugh].

 

He wonders if giving up smoking after 50 years had anything to do with getting MND but his...

He wonders if giving up smoking after 50 years had anything to do with getting MND but his...

Age at interview: 60
Sex: Male
Age at diagnosis: 59
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Have you ever had any thoughts about what might have caused it in your case?

I don't know. I can't think of any specific thing that you could ally it to. I suppose you could say giving up smoking, maybe, but I wouldn't have thought so. One thing I'm very proud of is when I was told I was dying I didn't go back to smoking. I've kept a clean sheet. And my nurse at our practice, who was my conscience when I gave up smoking - I did it through her, and the patches and things - holds me up as a glowing example. But I gave up smoking because everybody needs a reason, and my reason for giving up smoking wasn't health, or my health, it was the health of my grandchildren. And I promised my daughters that on no way I would ever smoke in front of them while they were pregnant or my grandchildren. So I gave up when I knew they were pregnant. And I haven't had a cigarette since. And that was the 3rd of September 2004. So two years.

Engraved on your memory.

Two years in now [laughs]. Well, it is, it's a big thing. I smoked forty a day and I'd smoked since I was 10 years old in reality. So, you know, fifty years of smoking pretty much. But I do feel better for it [laughs]. But, yeah, that's the only thing. No, I don't, I don't think there was, you know, I wouldn't say there was anything that I would say was the cause of it. There's nothing there. I think everybody tries to find something and invent something. And in, part of the discussions with my specialist was that, you know, 'You might think, you know, this caused it or that's caused, but we don't know, you know, we just don't know. We don't know whether it's hereditary.' Footballers predominant in motor neurone, a lot of footballers are affected by it. And yet it can affect anybody, you know. I think the nicest thing that was said was that, 'It's not something you've done. You haven't done anything to cause this.' If I'd have got cancer then I could have said, 'Yeah, well, it's my smoking, you know. I deserve it, you know. I shouldn't have smoked all them fags, thrown all that money away in smoke. I jolly well deserve it.' But you can't, because you don't know, you know. You haven't done anything to deserve it. And it's no use turning round and saying, 'God, what have I done to deserve this?' or anything else. You've got it. 

I think one of the things that is a strength to me, and has been throughout my life, is that I have had the ability to say, when I have a problem, 'Can I do something about it? Yes. Not a problem then. I can cure it. I can go out and do something positive to get rid of it or diminish it. Can I do something about it? No. Well, why worry? you know. It's not going to get me anywhere.' And I've lived my life with that belief. It's very difficult [laughs] not to worry, but I've actually lived it with that. And with motor neurone, 'Can I do something about it? Yes, I can. I can go and be part of the trials. I can do this. I can do positive things. I can raise money. You know, I have lots of skills I can use to help motor neurone disease, and, and be positive about it. Can I do anything about curing it? No.' You know.

Not knowing what had caused their condition was frustrating for some people. While some could live with the idea that it was just chance, others struggled with this idea, especially if they and their families had always been very fit and healthy. 

 

He can't understand why both he and his wife developed MND. He thought playing a lot of sport might have had something to do with it in his case.

He can't understand why both he and his wife developed MND. He thought playing a lot of sport might have had something to do with it in his case.

Age at interview: 76
Sex: Male
Age at diagnosis: 61
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Have you ever thought yourself about the causes?

I've thought a lot about the causes and I'm no further forward. I have no idea. As far as I'm aware there's no history of this in my mother's or my father's side, or in my wife's family either, and, and she had two brothers, so why should she have it and the two brothers not? I had one brother and I've got lots of cousins. My mother came from a family of ten and my father came from a family of seven and there's none of this, none of my cousins or relations have been affected, nor was my brother so why me? I don't know. I mean I've done all the sort of things that young men sort of, you know, played lots of sports, ridden motorbikes perhaps more quickly than was sensible and driven cars perhaps more quickly but it's nothing that I can lay my finger on obviously. Being a goalkeeper you've got lots of knocks and bumps and this sort of thing but that's a long time ago, so I haven't got a clue.
 

Some had done a lot of reading and searching on the internet for different theories about causes and the latest research evidence. 

 

He has read up on suggested causes. He worked in farming and wonders whether exposure to sheep dip affected him, or whether it's just chance.

He has read up on suggested causes. He worked in farming and wonders whether exposure to sheep dip affected him, or whether it's just chance.

Age at interview: 60
Sex: Male
Age at diagnosis: 56
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A slight worry is what causes the MND. I mean you know about the two groups of people who have MND in clusters. The first are Italian footballers, who one assumes probably from their diving have eaten too much grass which has been infected, I don't know, organophosphates. I've no idea why Italian footballers - it may be something in their diet. It doesn't seem to be their lives, so it doesn't seem to be environmental. 

The other are people in Guam, who have a really rather odd diet and they eat fruit bats as part of their diet. This seems to give them toxicity. I think it's toxicity from the fruit the fruit bats eat, which passes through the fruit bats and gets concentrated. And they have about a 200 per cent chance of getting motor neurone disease greater than average. But apart from that, it doesn't seem to be related to race, it doesn't seem to be related to sex, it doesn't seem to be related to whereabouts in the world you live, to diet. I mean, Japanese people who eat fish and rice are just as likely to get it as people in Europe who eat a meat diet or South Americans or whatever. It just seems to be totally - apart from these two clusters. The only other possible cluster, in [county] we don't have many people who work in forestry and farming, but maybe people who worked in forestry and farming or gardening have a higher possibility, which gives you the horrible thought that it might be organophosphates. And I happened, I used as a kid to work on a couple of farms and I've done sheep dipping and things like that in my past. And you wonder whether some days when I was 20, in my 20s, dipping sheep without gloves and without proper protection, as we did in those days, may just have caused it. I don't know. I can't think of anything, but it's the only possibility that sort of sets me apart from ordinary people. I've had a normal diet apart from that - not wonderfully healthy but quite good these days. I don't seem to have done anything else. So it's perhaps my days of working with cattle and sheep, on hill sheep farms, hill cattle farms. I can't think of anything else. Maybe just statistical. I'm the one they choose. Two hundredth thousandth person or something.

Footnote

The reasons why people in Guam have a high rate of MND are still unclear. A recent paper at the International MND Symposium has presented some evidence that the main risk factor may be toxins in flour made from cycad fruit, rather than consumption of fruit bats, but that a genetic factor may also be important in triggering MND. A summary is available at'

www.mndassociation.org/research

Research suggests there is a higher risk of developing MND amongst footballers and farmworkers, but the reason why is still unclear. The MND Association provides a series of questions and answers at'

www.mndassociation.org/research
 

People mentioned a wide variety of what they thought might be possible risk factors from their own experience, including:

  • A stressful lifestyle or particularly stressful events
  • Diet
  • Exposure to chemicals (especially in agricultural work and on food, but also when working as a firefighter and installing industrial machinery)
  • Exercise, sport and sports injuries
  • Other injury (including head injuries and leg injuries)
  • Previous chemotherapy and surgery
  • Medication for depression
  • Amalgam teeth fillings
  • Throat infections, viruses
  • Lyme disease
  • Genetics
  • Frequent travelling (including muscle cramps caused by sitting still for long periods).
 

She has thought of many things which might have caused her MND including injury, stress, dental...

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She has thought of many things which might have caused her MND including injury, stress, dental...

Age at interview: 63
Sex: Female
Age at diagnosis: 62
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I thought back over the previous few months for an explanation - could I have trapped a nerve in an attempt to do the exercise that was expected of me? The car hatchback lid dropped on my head 2 weeks previously - did this cause a trauma to my skull? I was suffering a certain amount of stress, in that I was main carer for my difficult mother-in-law - could this be part of the problem? My mother died in her 50s with cancer of the throat and for 4 years she could not speak. This is an uncanny connection. That was another fear for me - could this be predisposition to cancer?

In the previous year I had a vile reaction in my throat when the farmer was crop spraying opposite our house - could this be connected? Crop spraying had been going on for 30 years, but this was the only time I felt the reaction directly in my throat. My mouth remained sore after the spraying incident and it left me with sensitivity to strong smells, tastes, certain fruits, perfumes, some plants, chemicals, etcetera. I couldn't identify changes to any other parts of my body, simply the mouth and throat area. However, it suddenly opened my eyes to possible damage to our family's health; my husband suffered from neck and head aches for as long as I can remember and my twin daughters also have unusually sensitive muscles. Now, looking back, perhaps growing vegetables in our allotment alongside the treated field might well have put us all at risk.

I had face pain a few years ago connected with over-large fillings. When one was ground off a little after my protestations, the face pain disappeared. Was this a TMJ [temporo-mandibular joint] problem? Was the amalgam in my teeth leeching into my system? In 1999 I caught a virus and was unwell for one year and was advised to stop physical work and change my life style. Now, looking back, I believe I had ME [myalgic encephalopathy or chronic fatigue syndrome] - can this be a pre-cursor to motor neurone disease? In the light of my new problem, I went back to my dentist for his advice and he was certain that it was neurological rather than physical, even though he had to admit I had unusual face and neck aches over the years.

 

She had already met her future husband at university before her father died of MND. They assumed...

She had already met her future husband at university before her father died of MND. They assumed...

Age at interview: 34
Sex: Female
Age at diagnosis: 31
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I, my husband, husband and I met at university, when we were 18, in our first week at university. He was very convenient. He was in the dorm opposite me in halls. So we were together through the whole of university, and so we'd been together for three, four years probably when Dad died, which has been a huge help actually now going through all this. I don't know why. I think it's because it, it helps set the scene a bit for [husband]. And I think before we got married he, he knew the - [tearful] he knew the deal as well.

I can't, I don't really have a memory of any specific discussions, although, ...because it was matter of fact. You know, he knew that, we knew that, you know, my uncle had died and my father had died, and also their mother, actually. Looking back at the records now, although they diagnosed it as maybe a stroke or, you know, something like that, that was back then, but actually looking at it now it's likely that she had it as well. But they can't go back any further because she, they think that she was adopted. So that's where the family history ends. So I don't remember any specific discussions. But obviously [husband] knew as well as I did. Because it probably wasn't really clear until Dad died what the implications were for us. And I think we felt that it's something that affects older people.

Some people we talked to, who had younger children, worried especially about whether their MND might be an inherited form. Knowing that MND runs in the family raises particular issues for people about whether they themselves will get the condition, and whether their children and other family members will also get the condition. Gene testing is not always possible, if there is no clear family history.

 

So far her children have decided not to be tested for the SOD-1 gene mutation. At the moment...

So far her children have decided not to be tested for the SOD-1 gene mutation. At the moment...

Age at interview: 45
Sex: Female
Age at diagnosis: 37
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Have, have you talked to them about how they feel about testing?

I have. At the moment they don't want to know. They just want to get on with their life. Neither of them at the moment want children, for obvious reasons. When my son was 16, he actually asked me if a doctor would consider giving him a vasectomy. Which he's, we've never really looked into that, other than that first conversation, because I think that's a bit drastic.

I suppose that might be the point at which they would actually want to have a test. If they had a partner and'

Yes.

'they wanted to have children after all, then they might.

Well, it's something that I've got no control over. It's actually their, their decision, their choice. And I really don't think, although I could cope, if I found out that I'd passed it on to one or both of them I couldn't cope with that information myself. And one of the things I do know is that if one of them was to develop it, often the one that is okay has loads of trouble dealing with the news that they're going to lose a brother or sister. So it's, it's like a ripple effect. Nothing's as straightforward. Because my neurologist was just talking about maybe giving riluzole to people with the genetic form in the hope that it might correct or prevent it on the on-start. But in order to do that they have to have a genetic test. So it's a doubled-edged sword whether they really want to know - if so, they might be. There's a lot of issues really around genetic testing. But I do know that if they decided to have a family later on, we do have the technology to screen the embryos and take the SOD-1 mutation out, which would technically prevent them from having any more children with that, but then again, in order to do that they would then have to find out if they were carrying the genes, or they would know they were carrying the gene if one of the embryos was faulty, so.

Mmm, yes, it raises huge issues.

It is. It's a massive - I remember my neurologist saying to me that until I'd openly talked about it, he was just coming at it from a medical point of view' 'Oh, well, it's better if they know because then if any treatments come out we can give them' and this. But he hadn't actually realised the huge knock-on effect it has on their life, on mortgages, and...

Have they had counselling separately about?

Not at the moment, no. And they can't, you can't do anything about genetic counselling, really, till they're 18. I did set up a link with a counsellor when they were about 12 in the early days, in the hope that if they ever wanted to talk there was someone there. But so far they haven't taken me up on that.

 

She might not have had children if she'd known she had familial MND, but she's glad she has them....

She might not have had children if she'd known she had familial MND, but she's glad she has them....

Age at interview: 45
Sex: Female
Age at diagnosis: 37
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But I'm also aware that I've got to be as positive as I can, because I want the children to have positive memories of MND, not the negative one that I had originally. Because God forbid if one day one of them develops it, I don't want them to then think, 'My life's over.' I want them to remember that I've abseiled off a building with MND, I've met Cliff Richard with MND. I've done a lot of things that I would never have done previously. I've done the Great North Run. And I've tried to let - and we have a laugh. I try and - it's the most important thing that life goes on, it's not the end of the world, and try and give them as positive an outlook as I can. But one of the hardest questions I've ever been asked, [son] was 11 and he just point blank sat - I was in the car, we were parked up - and he said, 'Did you know when you had me that you were going to give me something that I was going to die of?' And I remember sitting there just frozen, thinking, 'How on earth do I answer this question?' And I honestly said, '[son], I didn't know.' And thankfully I didn't know. At the time that I had my, I had my children I didn't know for definite that it was. But I wouldn't have not had them. And I had to explain to him that it didn't make any difference, and hopefully he won't have to develop MND, and one day the cure will - hopefully in their lifetime - I don't think it's going to happen in mine but I've got every faith that, for them, that things will be different. And that's the one thing that I can keep telling them.

So would you, I think you said you, you would have had children anyway, even if you had known there was a family.

No. I think had I known, I would have chose not to have children. But then that's an easy assumption to make when you've already got them. So, and I wouldn't be without them now. They keep me going. They're a reason to be here. So I've got a lot to be thankful for. But I really don't think I would have gone ahead had I known for definite that this was going to happen.

So you and your sister, have you got other brothers and sisters?

I've got another sister, who so - is fine. 

And were you all, you and your uncles and mother, were you all much the same age when it was diagnosed?

Pretty much. My mum was 37 when she died. Her brother was only 28 when he was diagnosed. Her other brother was the exception. He was 50 when he was diagnosed. My sister was 39 when she was diagnosed. I was 37. And yet my cousin in Tasmania was like her father. She was 50 this year, so she's the same age as her father was when he was diagnosed. Yet we seem to be around the same age as our mother. And our grandfather - and I was saying he probably did have motor neurone disease - he died when he was 42. So it seems, seems to be a connection with age.

 

Her father did not have a known mutation so she did not have genetic testing. She had already...

Her father did not have a known mutation so she did not have genetic testing. She had already...

Age at interview: 34
Sex: Female
Age at diagnosis: 31
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And did, did any of you ever have any genetic testing?

No. We, I know my sisters and my cousins did talk about it, and at the time there wasn't really any testing available. We, I think they were just starting to develop it and they'd found there was some testing available for the SOD-1 gene. But we, I think they tested my father's blood and found that it didn't have the SOD-1 gene mutation. So we felt that, you know, there was no point. But before that I think my sisters and I had decided that there wasn't any point anyway.

It wasn't really going to be of any help to us because it wasn't, it wasn't going to change any decisions we made or the way that we led our life. It wasn't, the testing isn't conclusive enough. You know, that, we were told that, “Even if you are found to have the SOD-1 mutation, then you may well not go on to develop it.” So we didn't find that it was very helpful. And it wasn't an option to us anyway in the end.

When you say it wouldn't affect any, any decisions that any of you made, is that also true about having children?

I think… well, [husband] and I did go and see - oh - my husband and I did go and see a doctor that specialised in genetics and he - just to talk about this issue when I was first diagnosed. And we felt that the, if we had the test, it wasn't going to give us enough conclusive evidence. And also for us, having children when I'd already been diagnosed was going to be too much of a bigger strain. I think for my sisters, we - I don't think it would have affected their decision. I think - although now, in hindsight now that I've been, been diagnosed, I don't know. We haven't really talked on that level. Although I know that within the family we're all very keen to kind of stamp out the gene. And if testing is going to allow - the research into testing is, will hopefully allow decisions to be made in the future that will really help stamp out the genes, mutations, or you know - and embryonic testing and that sort of stuff.


See our resources for links to further information on research around causes of MND. You can also find out more on the Research pages of the MND Association website.

Last reviewed August 2017.
Last updated August 2017.

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