What is the vagus nerve and can you really reset it?

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12:27Arshad Majid:Ashad Majeed, you're a professor of cerebrovascular neurology at the University of Sheffield and you're an expert in the vagus nerve. Welcome to Strange Health.

12:38Katie Edwards:Well, thank you for inviting me. I'm very happy to be here.

12:41Arshad Majid:So clearly it's become quite a, you know, a focus in wellness culture, but can it be stimulated then or hacked like we see on social media? Dr.

12:51Katie Edwards:It certainly can be stimulated. I'll show you devices in a few minutes that can actually stimulate the vagus nerve. These are medical devices. I think the question you're asking me is, are there other ways we can stimulate it? Now, it's not like a switch where you can switch it on and switch it off, but it's possible that we can indirectly modulate its activity. For example, if we take deep breaths in and out. Now what that does, especially the long exhale, this tells the brain that there's not danger here. Just calm down, just calm down. That can indirectly activate the vagus nerve and that slows the heart rate down and can induce a relaxed state.

13:51Katie Edwards:How much we can modulate its activities is not really well studied using these techniques. We don't know. In some people, taking a few breaths, you know, calms them down, whereas other people, it really doesn't do anything. The other techniques, using electrical devices, they're more reliable in stimulating the vagus nerve.

14:19Arshad Majid:So is it actually good for you to activate it then, or is it just kind of mainly a way to relax?

14:25Katie Edwards:That's a very, very good question, and that's what we're trying to study at the moment. We don't fully understand what the vagus nerve does, and we're just beginning to scratch the surface. We do know that it has a calming effect on the body and that calming effect, that relax and digest effect, has beneficial effects in itself. It can reduce your heart rate, reduce your blood pressure and induce a calming state. And certainly we think that that's a good thing compared to being on edge and being in a state of arousal or anger or stress, for example.

15:08Arshad Majid:So what does the medical vagus nerve stimulation involve in practice? Can you describe both the invasive and the non-invasive?

15:16Katie Edwards:Yes, there are two main ways that we can stimulate the vagus nerve medically. One of them is the invasive way, and that involves an operation. A little pacemaker is inserted into the chest and the wires are wrapped around the vagus nerve in the neck. And using that pacemaker, we can directly stimulate the vagus nerve. Now, as you can imagine, that involves an operation, it involves cost, patients coming into hospital having general anesthesia. So that's not practical for many health systems. In the US, it's used a lot, but less so in the UK with the resource constraints that we have in the NHS.

16:04Katie Edwards:The other way which we've been very, very interested in is can we stimulate the vagus nerve reliably and effectively non-invasively? Studies using cadavers have shown that there's a small branch that leaves the main trunk of the vagus nerve and goes to the ear. And what we've been doing is using medical devices, which I'll show you in a minute, stimulating that branch.

16:33Arshad Majid:Now, I've seen people doing this, trying to do this themselves. Is that the same thing?

16:38Katie Edwards:Now, whether just pushing like this on your ear or circling or just applying some sort of pressure stimulates the vagus nerve is unknown. It's really not been studied and it may vary from person to person. I've seen people trying to push behind their ears as well and so we don't really know whether it reliably stimulates the vagus nerve. The way we're doing it, we're doing it electrically. In that way, we're using an electrode, so we're stimulating the vagus nerve directly using electrical pulses.

17:21Arshad Majid:You mentioned invasive vagus nerve stimulation. What conditions is stimulating the vagus nerve invasively currently used for, and what's being researched next?

17:34Katie Edwards:In the United States, it's approved for two things. Firstly, treatment-resistant epilepsy, so people who are still having seizures despite being on medication. It's also approved for depression, treatment-resistant depression, so patients who are still significantly depressed despite optimal medical therapy. More recently, people have started to investigate it for other conditions like migraine, also something called cluster headaches, which are very severe headaches. There's a lot of interest in inflammatory bowel disease, such as Crohn's disease, but the two main areas where it's used is in depression and epilepsy.

18:27Arshad Majid:And what about non-invasive? Is it actually medically approved for anything yet?

18:33Katie Edwards:The trials are going on at the moment. We're still waiting for more data. Small studies have shown it has a beneficial effect in reducing seizures in epilepsy and also may have benefit in depression. But these are small studies, so bigger studies are actually underway at the moment.

18:57Arshad Majid:So how do the clinical or research devices and how do they differ from consumer wellness devices?

19:04Katie Edwards:When it comes to the medical devices, you can't have a certification as a medical device and call yourself a treatment for a disease unless you've satisfied rigorous regulations such as the safety of the device, showing that it works reliably, showing evidence from clinical studies that there's benefit from this. Whereas with consumer devices, there's no oversight. People can self-declare that it's a wellness device or a health device without proper testing in the vast majority of cases and without any oversight at all. So we're really not sure what we're getting with consumer devices because people can make claims but that have not been verified scientifically.

20:04Arshad Majid:So this sounds like a great moment for you to show us a couple of the devices that you use.

20:10Katie Edwards:Yes, yes, let me show you.

20:12Arshad Majid:I'm excited.

20:15Katie Edwards:This is one of the devices. It's a stimulator. It's about maybe a third of the size of a smartphone. And then there's a little electrode here that you attach to the ear. And it stimulates a branch of the vagus directly using this.

20:35Arshad Majid:Does that one go right in your ear?

20:37Katie Edwards:That fits on a part of your ear called the tragus. Right. So it doesn't actually go inside, it sits on the outside. Oh. I'll show you this other device, which is probably the oldest of the devices. There's a lot of research that's been done using this device, and this fits inside the ear. It's a part of the ear that's called the concha. And as you can see, this is about half the size of a smartphone and you can just activate it, put in the electrode and sit and watch TV if you want to.

21:15Arshad Majid:Oh, wow. So how long do you do it for?

21:18Katie Edwards:Well, that's a really good question and that's what we're trying to figure out. At the moment, what we don't know is how long you should stimulate for optimal effect. Secondly, we don't know what the intensity of the stimulation should be and what the frequency should be. And we're trying to work this out. But usually the recommendations are, for example, it's used quite a lot in depression and in epilepsy. It's usually half an hour to an hour a day, but it can vary. It can vary.

21:58Arshad Majid:Right. And you're currently running another research project that's looking at the effectiveness of non-invasive vagus nerve stimulation for stroke patients. Can you tell us a bit about what you're doing?

22:09Katie Edwards:Yes. So this is a very exciting study that will be completed this year. It's the largest neuromodulation or neurostimulation study that's ever been done. and we are looking to see whether stimulating the vagus nerve non-invasively in patients who have had a stroke and who have arm weakness, can we improve the function of the arm? So what we're doing is that we're combining stimulating the vagus nerve non-invasively with rehabilitation when patients move their arm to see whether we can encourage the brain to rewire itself. Sometimes that's referred to as neuroplasticity. So good areas of the brain that have not been damaged by the stroke take over the function of the damaged areas.

23:05Katie Edwards:So we should have the results of that trial by the end of this year. Now at the moment, because it's a double blind trial, I don't know who's actually receiving treatment and who's not receiving treatment. But many participants have written to us and said that they've had huge benefits. But I must say that I don't know whether they've actually received treatment or not.

23:31Arshad Majid:So this sounds amazing, Ashad. So how significant do you think these results are going to be?

23:37Katie Edwards:Most patients have arm weakness after stroke. about 60 % in some studies. Now, if we can enhance their arm function, then we can change their lives. So, for example, if a patient can't open a door using a key, if they can make a cup of tea, get dressed, this can have significant impact on their life. It might even lead to them getting gainful employment. But I must say that this is research, so I don't know whether it's going to be positive. That's why we're doing the study. But we also have a sub-study to see if we can better understand who benefits and who doesn't, and which areas of the brain are activated that lead to this improved function.

24:32Arshad Majid:And so with all these kinds of studies, how hard is it though to actually understand if the vagus nerve is being stimulated?

24:39Katie Edwards:I think that's a really, really good question and I think that we're not 100 % sure whether we're stimulating the vagus nerve. What we can say is that the changes that we do see on the brain scans look very similar to the changes that we see with the invasive where we're sure we're stimulating the vagus nerve. So those changes on the brain scans give us some confidence that we're stimulating the vagus. Now, at the end of the day, if the patient gets benefit and some other nerve was also stimulated, then I can live with that as long as they've had some benefit from it. I'm okay with that.

25:25Arshad Majid:Absolutely. So what other research that is ongoing into vagus nerve stimulation that you think people should either know about or that you're really excited about?

25:34Katie Edwards:Well, I think that if our study is positive, then this will be a huge stimulus for vagus nerve research. Some of the things that we're looking at at the moment is we're trying to see whether we can improve speech in patients who have had a stroke. Other people are looking at dementia, for example. Does it improve the symptoms of dementia? Does it help with sleep? Does it help with mood problems after stroke? And there's also a lot of interest in other conditions like rheumatoid arthritis, and I mentioned previously inflammatory bowel disease.

26:12Arshad Majid:So given all the videos out there, because I've seen loads on social media where people are trying to stimulate the vagus nerve, etc. Are there any risks or side effects that you think people should know about who are trying to kind of self-stimulate the vagus nerve?

26:28Katie Edwards:If patients feel more relaxed and they feel better after they've done these procedures and perhaps stimulated the vagus, if they feel better, then who am I to tell them not to do it? Right. But we have to be careful. So one of the things that I've found is when I've tested these devices on myself, I feel very depressed. It has a paradoxical effect on me. So I feel very low. My mood becomes very low. And so we have to be careful because the effect of stimulation of the vagus may be different in some patients. So that's the only caution that I would have. But if somebody's getting benefit, if it helps them relax, by putting their finger in their ear and moving it around, if it helps them, then do it.

27:24Arshad Majid:I mean, that's absolutely fascinating. Is that a well-known side effect in other studies?

27:31Katie Edwards:Yes, some people do have side effects. For example, they can get headaches, they can have migraines, it can make migraines worse. But that's only a small minority. And we're trying to figure out who is likely to get these side effects. The vast majority don't have any significant side effects.

27:51Arshad Majid:Okay, so what misconception about the vagus nerve would you most like to clear up? Well, I think that it's not a panacea.

28:01Katie Edwards:It's not a cure-all. I think that in many conditions, there are many different components that cause the problem. However, I think if we can better understand what the vagus nerve does, if we can better understand how to stimulate it optimally, then there's great potential for therapeutic gain.

28:25Arshad Majid:Yeah. And what should the public take away from vagus research today?

28:32Katie Edwards:A better understanding of the vagus that it's not an on-off switch, that these techniques may not be stimulating the vagus nerve, the things that they see on social media, but that in the next couple of years we'll know much more. And my prediction is there'll be many more devices that will come onto the market that have been properly tested and have been approved for that condition.

28:58Arshad Majid:Brilliant. Well, that was absolutely fascinating. Professor Arshad Majeed, Thank you so much for joining Strange Health. That was absolutely fascinating. I could talk to you all day. Thank you.

29:08Katie Edwards:Thank you.

29:11Arshad Majid:That was really interesting, wasn't it, Dan? I mean, the vagus nerve then really is important.

29:16Dan Baumgardt:Yeah, it is. And, you know, we've talked a little bit about how the vagus nerve has so many different functions and the variable ways in which you could potentially stimulate it. But I just think this was amazing how much promise there is towards it for the future.

29:32Arshad Majid:Yeah, but it's not a magic switch though, is it?

29:34Dan Baumgardt:No, it's not. And in medicine, vagus nerve stimulation is a specific, carefully controlled intervention used for particular conditions, cardiac conditions, for instance, with trained clinicians and regulated devices. And in the medical world, we call them vagal manoeuvres. It's not like army manoeuvres. It's not like running an assault course. And God knows I would be terrible at doing them myself. But you do have to take due care and attention because vagal manoeuvres can sometimes overstimulate the vagus nerve. And sometimes in doing them, you can trigger other complications as well.

30:03Arshad Majid:I mean, vagal manoeuvres does sound a bit dodged, doesn't it? It does. It does sound like it might cause problems.

30:09Dan Baumgardt:It sounds a little bit OTT.

30:11Arshad Majid:So when we talk about, or when you talk about vagal manoeuvres, is this, are we talking about calming wellness techniques or are these actual medical interventions?

30:22Dan Baumgardt:They are medical interventions. They can actually be used to treat certain underlying medical conditions. Some of them involve very simple actions. Take the Valsalva manoeuvre, which is a really sophisticated way of trying to bear down and do a bowel movement on the loo. Essentially, what you do is you exhale. We're not conscious that we're doing this. We just do it automatically, don't we, when we go to the toilet. But what you're doing effectively when you're going to the loo is exhaling against a closed mouth and nose in order to increase the pressure inside your body, which has the added effect of help.

30:55Dan Baumgardt:I'd better not try that, actually. I was giving that a go.

30:59Arshad Majid:No,

31:01Dan Baumgardt:that's all right. Don't worry. But yeah, you exhale against a closed mouth and nose and it increases the pressure inside your body, which has that added effect of helping you to defecate, to have a bowel movement.

31:12Arshad Majid:You see, I was not expecting to say that because Valsalva manoeuvre sounds like something really cool that Vikings used to do. But it's just making you have a poo, isn't it?

31:22Dan Baumgardt:It is. Yeah. Yeah. In all honesty, that's exactly what it is. And when I speak to my students about it in physiology, that's what I sort of describe the Valsalva manoeuvre as. It's like straining when you're on the loo.

31:31Arshad Majid:Why would you do that? What can it be used for medically?

31:36Dan Baumgardt:It's used for certain cardiac conditions. So some patients find that their heart goes into abnormal rhythm, which can make it go very, very fast. And in doing so, they don't tend to beat as effectively. And it can make you feel dizzy, faint and give you this feeling of palpitations in your chest. So sometimes the Valsalva manoeuvre can be used and sometimes patients are told and trained to do it themselves. it can help reduce their heart rate and get it back into a normal rhythm. But the other thing that you can do as well that helps it along is sometimes we get patients to blow into something forcefully, something like a straw or the end of like a lid that comes on a biro.

32:13Dan Baumgardt:You can blow into the end of that and that can help achieve the same thing.

32:16Arshad Majid:So would blowing into the end of a pen lid, would that make of a poo?

32:20Dan Baumgardt:No, no, no, no, not necessarily. Because the actual act of doing a poo involves much more than just straining down. It involves your sphincters and your gastrointestinal tract opening and allowing them through. And that's what helps us because I said, if we were going around, you know, making the slightest of strains, then we would lose things quite spectacularly. But our pelvic floor and our muscles help hold everything in.

32:47Arshad Majid:I'm asking all the important questions, Dan. Of course.

32:50Dan Baumgardt:But this is what Strange Health is all about, isn't it?

32:53Arshad Majid:So just to be absolutely clear, then there are some techniques that you shouldn't be trying at home.

32:58Dan Baumgardt:Yeah, absolutely. So one example, for instance, is massaging the neck around the vessels. It's what we call carotid sinus massage. There's definite indications for it and it can be useful in the clinical setting. But this is where it should be done by a clinician or professional who's been trained in doing it, because in doing so, you can interfere with blood flow or damage the blood vessels, especially if you're doing it too vigorously. When clinicians do it, they only ever do one side at a time and only for a short period of time, because otherwise you can reduce the blood flow to the head or damage the vessels.

33:30Dan Baumgardt:And in doing so, you can fall over or collapse.

33:34Arshad Majid:Oh my goodness.

33:35Dan Baumgardt:And the other thing with carotid sinus massage as well is that doctors will generally do it with a heart trace or ECG running. So it allows them to monitor the heart rate and if there's any changes in the heart rhythm at all. So that's why it's also really important that it's done in hospital and by a trained professional not at home. And I think that's why people need to go very carefully with any advice they're receiving from other people about stimulating the vagus nerve and where they're getting it from. You need to go carefully. Too much vagus nerve activation can lower your heart rate and your blood pressure too much, making you faint, dizzy, or indeed even pass out.

34:10Arshad Majid:So just to be really clear then, if somebody feels calmer after doing some of these things like, you know, splashing wash on the face or like humming the theme tune to neighbors or whatever, like that's real and, you know, carry on doing it. But it doesn't necessarily mean that you're directly stimulating the vagus nerve or, you know, and it's not necessarily something you should be experimenting or trying to push a bit further.

34:33Dan Baumgardt:Yes, exactly. And it's about feeling calmer that matters. When you're doing all these simple things like gargling or singing or humming, whatever, it's instilling that sense of calm. Feeling calmer matters. And we shouldn't assume that we know that the vagus nerve is directly being activated, perhaps we're activating a whole load of other nerves. There's so many nerves within our body controlling different things all at the same time. Gentle things that help you relax are fine. Trying to deliberately activate a nerve, especially in some of the extreme ways that we're seeing and that we've seen today, that's where risks may well start to outweigh the benefits.

35:05Arshad Majid:Especially when the claims that are being used to sell devices and techniques aren't necessarily backed by good evidence.

35:11Dan Baumgardt:No, and I think that's key. It's where the evidence is. And that's what I really appreciated for Marsha was how honest he was about where the research is coming from and where it is genuinely promising, particularly in things like stroke recovery, where we still don't have all the answers.

35:26Arshad Majid:So if there's one thing to remember from this episode, then it's this, the vagus nerve is real. Medical vagus nerve stimulation is real, but not everything described as vagus nerve activation is necessarily doing what people think it is.

35:41Dan Baumgardt:Exactly. And if you're seeing big health promises online, it's always worth asking what evidence they're actually based around.

35:48Arshad Majid:Huge thanks to Professor Arshad Majid for helping us make sense of a topic that's become surprisingly popular.

35:54Dan Baumgardt:And if you enjoyed this episode, hit subscribe, leave us a review and share it with someone who's been told to hum their way to better health.

36:01Arshad Majid:And if you've seen a health claim online and you've thought, that can't possibly be right, we want to hear from you. So email us at strangehealthattheconversation.com that's strangehealth all one word at theconversationaloneword.com.

36:16Dan Baumgardt:Strange Health is produced by Gemma Ware with editing and mixing by Anouk Millet and artwork by Alice Mason.

36:23Arshad Majid:Thanks for listening.

36:24Dan Baumgardt:Until next time guys, thanks.