In Conversation With

Dr Koen Schruers Discusses Neuromodulation Treatments for Mental Health


In this episode we talk to Dr. Koen Schruers, Professor of affective neuroscience at Maastricht University. Dr. Schruers is an expert in his field and has conducted extensive studies about neuromodulation. We discuss the role of neuromodulation techniques in the treatment of mental disorders.


Dr. Koen Schruers
Professor of affective neuroscience at Maastricht University


Dr Elisabetta Burchi
Clinical Psychiatrist


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Dr Elisabetta Burchi 0:05

Hello, today we are here with Dr. Koen Schruers.

Dr. Koen Schruers is Professor of affective neuroscience at Maastricht University who has done extensive studies about neuromodulation. And he will help us understand more about the role of neurostimulation techniques in the treatment of mental disorders. Their advantages and risks, and why there is still reluctance in their acceptance? Koen, do you want to say something about yourself and your work. 


Dr Koen Schruers 0:38

Yeah, thank you. I'll maybe try to briefly introduce myself. I'm working at Maastricht University, although I'm a Belgian from birth. I'm a psychiatrist by training. I did my training at Louisville University in Belgium. My specialist training Ph.D. later on at master university in the field of experimental panic. A lot of my work is gone into experimental panic provocation. Then clinically, as I treat mainly anxiety disorders, OCD trauma, and depression.  So my research has broadened a little bit but mainly staying in the field of affective disorders and into the mechanisms of what are these disorders? And what are the mechanisms of the treatments we have for these disorders?

So I'm not really on a trial list. I'm not very much occupied by which treatment works best, but more into why do treatments work better or how do the treatment work? So that's my field of research. And regarding neurostimulation, the majority of my experience is actually in deep brain stimulation in obsessive-compulsive disorder and for Tourette's disorder. So we have a program at mastery treating these together obviously with the department of neurosurgery, and that's where our part of our research goes as well. And we're now moving into the field of non-invasive brain stimulation as well. Also, from my part mainly directed as obsessive-compulsive disorders but clinically also to other affected disorders. Well, that's in a nutshell what I do.


Dr Elisabetta Burchi 2:13

Fantastic, so you talked about why certain treatments work better than others and but can you say something about broadly what is neurostimulation about? 


Dr Koen Schruers 2:28

Well, I think what's the common denominator in these cases is electricity. It's a means of changing the brain. We can do that in many ways in psychiatry. We change the brain also by psychotherapy/ Many people forget that.

Still, psychotherapy is the solid evidence that it shows that changes the brain only in a very non-specific way, meaning that we don't know precisely how this affects the brain. I mean, the steps between delivering the therapy and then the end effect on the brain are not really known in detail. Broad lines, yes, but not into detail.

There's a little bit more understanding about the effect of drugs on the brain, but even then, we know usually quite well on which kind of receptors and which kind of cells are affected but regarding which circuits and in the brain and how they interact when drugs act on the brain is not really very well understood.

And the advantage of neural stimulation techniques is that, at least from a mechanistic point of view is that the understanding of the functional neuroanatomy of these techniques is much better.

So the understanding of their mechanism is better. We know less about the, let's say, molecular mechanisms that are obviously a downside. It's very hard to research also in humans and living believing people.

But that's it functional neuroanatomy on pro neuroanatomy level on circuit-level. I think there we do have an advantage. So, where we'd like to go in in psychiatry, moving from, let's say, therapies that fit broad categories of people towards a more personalized approach based on, let's say, brain dysfunction, apparently present in a certain person and not in another one.

I think there the avenues are possibly better with neurostimulation techniques.


Dr Elisabetta Burchi 4:30

Fantastic, so you told us that basically, all treatments that we use in psychiatry have something in common. The fact that they act on narrow circuits on neurons, and maybe neuromodulation techniques have the advantage that we can directly track the effect of neurons in circuits, so on paper, at least they are more precise.

They will allow us to do this personalized medicine even in psychiatry that we know is the future is that is the present hopefully probably we are still far from that.

And so, but just doing a step back. So neuromodulation techniques act directly on neurons and circuits. What kind of neuromodulation techniques broadly do we have? You already mentioned the DBS brain stimulations. What kind of techniques do we have


Dr Koen Schruers 5:31

Yes, nowadays, there's a whole range of neurostimulation techniques available, ranging from very non-invasive to invasive. On the invasive type, it's called deep brain stimulation, which is a derived technique originally from lesion neurosurgery.

It's more or less the functional counterpart of making a lesion but the choice of targets historically mainly comes from the literature and the inside that we have from brain lesion surgery in the early days of that.

There are very good applications on that mainly in psychiatry than in obsessive-compulsive disorder and Tourette's disorder with good effect studies but albeit still small studies when you compare it to drug studies or to psychotherapy, but still there are very good clinical effects, and people are refractory to all other three treatments.

There is still a considerable proportion to do respond to these techniques. Then there's obviously transcranial magnetic stimulation or direct current stimulation. Just let's say a more and less precise form of non-invasive stimulation. My personal expertise for experience is more with the GMS, particularly than now in the field of OCD.

Well, it's only, let's say, halfway to development. I'd say it to be a really established technique. For example, compared to depression, where it is not just very well researched but also accepted and put into treatment algorithms and protocols or in many countries already also where I work in the Netherlands it is recognized. 

It's reimbursed by the health insurance, so that's a very much established therapy in depression as a standalone therapy, so not in combination with without it. In its own right, it is an effective treatment for depression that's not the case yet for obsessive-compulsive disorder.

And the study that we're trying we'll be starting now is a multi-study scientist study in the Netherlands uh led by uh nervous from Amsterdam who's an internationally renowned expert in this field. We're looking at it from a slightly different language.

We positioned the intervention, let's say at stage two, first-line treatment for OCD in the Netherlands is behavior therapy. And our trial will be aimed at the people who failed who were not successful after the first treatment with the CBT, and then we will try to so to say boost the effect of CBT with TMS, So it's a combined treatment.

People will have concessively within each session a combination of exposure therapy and TMS. And that's what we're going to investigate.  So that's a different frame of mind than, for example, in depression, where it's a standard moment.

There have been studies into the treatment of OCD with TMS as a standalone therapy as well quite a lot, actually not very big ones but quite a lot of them with mixed success. I  think the success is there. I think it definitely has potential, but it's not as established as, for example, now in a depression. So that's one important technique that's really blooming now.

Like for example, vagal nerve stimulation of which there is an invasive and a non-invasive form. Invasive form involves well stimulating one of the vagus nerves in the neck with the portion that contains nerve fibres traveling to the brain.

And there's, of course, very recently the non-invasive form of that which is very elegantly stimulating the regular part of the vagus nerve, which is very non-invasive, and this is a field which is very much into in research now. I think it's mainly into the details of mechanism how does this work, and we're awaiting larger studies in clinical populations now.


Dr Elisabetta Burchi 9:53

Great so you we have these invasive techniques and non-invasive techniques that definitely have advantages. So mainly, we have studies on Transcranial Magnetic Stimulation, which is non-invasive and uses coils that produce some magnetic fields. Right.

And you told us that TMS has already been approved for resistance depression as standalone therapy while ferocity we are doing studies for making it a standalone therapy for resistant OCD, but there are studies also that you are conducting in which you use the TMS with other term psychotherapy.

And because definitely combination of treatments is possible.  So when we discuss narrow modulation, we can definitely think about something that we use with something else, right. And then you talked about also the stimulation of the vagus nerves that have been studied for multiple applications in depression and society, and I think that thinking about neuromodulation techniques, there are also studies in addiction, right.


Dr. Koen Schruers 11:25

Exactly, but very small ones.


Dr Elisabetta Burchi 11:28

We are still at the beginning.


Dr. Koen Schruers 11:35

So there's a little bit of experience of also, for example, with deep brain stimulation in eating disorders also very very small studies which I think by the way is a good indication potentially.


Dr Elisabetta Burchi 11:49

So it seems to me that there are a lot of advantages. What are the few risks? Clearly, there are differences between non-invasive and invasive. What are the main risks of both?


Dr. Koen Schruers 12:06

Well, an obvious risk of applying electrical current to the brain is causing an epileptic seizure which is in theory possible. For example, with TMS, that's a theoretical possibility. So having epilepsy is, therefore, an exclusive criteria to receive TMS.

For example, there are other side effects, for example, headaches and also, for example, when you apply TMS, it depends on which part of the skull that you're positioning the coil. When you come close to the forehead, close to the face, and then the musculature of the face, it can be very painful actually.

And that's the disadvantage of if you want to try to uh reach the frontal parts of the brain which especially for psychiatric indications and is relevant. This can be difficult, so, therefore, usually, the pre-motor area or lateral prefrontal cortex are used as entry points a little bit further away from the face musculature. So that's some of the disadvantages.

With deep brain stimulation, obviously, that's surgery, and that involves risks that are involved in any kind of surgery, namely bleeding and infections. These risks are small that you look at the prevalence they're way below one percent, but still, then they're always there, and you can never exclude them.

I always tell my patients when you're operated on, let's say at your turn, and you have an infection or something that's bad luck that's annoying, but it's a bit of a different thing where you're getting an infection in your brain. So it's a very small risk, but it's there.

And also, of course, when you have the brain stimulation, it's not just the electrodes that are put in place too, but they have to be tunneled. The wires have to be tunneled under the skin towards the battery, which is usually placed below the clavicle or on the abdomen and subcutaneously.

And then, depending on what type of battery you have, these need to be replaced more or less often. Classically non-rechargeable batteries have been used until now. We're moving it into the field of rechargeable batteries. But of course, when depending on how much you ask from this battery when you need to apply high voltage at higher currents, this battery will be depleted quite soon, and then it has to be replaced, which involves small surgery.

It's not brain surgery, but still, it's a small surgery with scar tissue and some risks of infection each time over again. So that is annoying, so now we have these rechargeable batteries, which on the first side are much better. On the other hand, charging times it's a bit like a new car's electrical crowd.

You're at the charger for quite a long time. so you need to be sitting still for an hour or two for these batteries to be charged, and that's really annoying as well because you can be sitting at home watching delivery, but you have to sit still for two hours for your battery to be charged every day and many people get annoyed by that as well. So these are technical, practical disadvantages.

What you see also psychiatrically often at the beginning of stimulation you see kind of a euphoric effect, so people having becoming more cheerful which obviously is what you hope. But sometimes, this goes further than we want.

We haven't seen, but it's been reported mania not in our groups until now, but it's been usually reported short-lived at it, and it recuperates, and of course, we can't treat that, but it's something you would not like things like headaches, sleep disturbances, sexual disturbances.

They've all been reported as side effects of the brain stimulation and also, for example, in the case of Tourette's disorder, whether the target is different in the brain. There are some reports of eye movement disorders as well. So there are some disadvantages that are inevitably linked to an invasive procedure.

If you look at it in balance, I always ask my patients afterward, in hindsight, would you not know what you know now and have lived what you have? Would you do it again or not. And until now, everyone has said yes, I would. But some of these it does put a constraint on your life.

There is no way around that, but you get something in return. If the therapeutic effect is good, which it is mostly not always but mostly, I think the balance is positive, but I think we will definitely looking for techniques that have the same benefit but less of a disadvantage.


Dr Elisabetta Burchi 17:00

Absolutely and I think that the non-invasive techniques go in this direction and minimize the risks and not only the risks but the expected adverse events. And so I was also thinking that for almost all of these techniques, we need to go into the hospital, into the clinic clearly for DBS but also for TMS.

While for other kinds of devices that you mentioned, like the stimulation of the Vagus nerve. We are now producing devices that can be portable, and so this is gonna be, you know, in terms of feasibility and also not for the patient in itself. It's gonna be much, much easier to address these new treatment approaches. Right, so I think this is an important aspect.


Dr. Koen Schruers 18:00

I agree completely.


Dr Elisabetta Burchi 18:02

I think we covered a lot of the topics. Let's see if we can summarize a little bit. So we started from what you said; your main interest is understanding why certain treatments work, and indeed, you know, according to psychiatry, there is this new paradigm that sees mental disorders as disorders of the brain.

It's a paradigm promoted by the former prior director of NMH of us, and that says indeed it seems trivial, but that mental disorders are disorders of the brain. So there is there are biological underpinnings, and I think this is quite in a for it's trivial for people that study the brain, but it's not trivial in society, right.

And maybe the stigma that still affects psychiatry is maybe responsible for the fact that the neuromodulation techniques have not yet been received acceptance. What do you think about that? And what should we do may be to promote a change in this mentality? Maybe this podcast, this interview, goes in that direction.


Dr Koen Schruers 19:37

Yes, maybe for a start, I think I would say there is no psychiatric disorder in which the brain is not involved. But that's to say it's no.  If you say, for example, is our psychiatric disorders of the brain, it has a slightly different connotation.

Because if you say it like that, you can be obviously accused of reductionism, and that's what many people do say "Oh you reduce my feelings my emotions my well-being too. near brain function near let's say the firing of cells, and I'm more than that". And that's a debate, of course, but you did that you can.

I think we're not going to solve that readily. But I don't think that at this stage, at least that you can reduce all psychiatric disorders to some precise dysfunction of the brain, and that's it. I don't know. Maybe one day we will, maybe we will never, but I think one thing is undisputed.

As I said before, there is no disorder of psychiatry in which the brain is not involved. I think that's beyond dispute. And that opens avenues to people, I think, in many ways. Also, a positive one because it's like the discussion about psychiatric disorders as being a disease, or is it something you know in the flow of life, and is it the form, let's say, on the continuity of normality? And part of life?

Or is it something medical and a disease? I think this is actually a trivial discussion that I think both ways to look at it.  But looking at it from a biological, medical point of view has an advantage. And it's also, I think, destigmatizing because it implies that what you have and the complaints that you have is not something the item of guilt is less. It's not due to what you did.

It's not your fault. It's not the fault of the parents of your history or whatever. It's a problem that you know anyone can have at a certain point of life that originates from, yes partly, of course, the risk you carry is determined by your genes and by your environment that you were raised in obviously,  is also determined by the things that you encounter in your life the adversity that obviously has been the way you cope with that obviously. 

But also, you know your biological constitution is an important aspect of that, and that's one you are given by birth. You can treat it. You can try to keep yourself fit as best as possible.  But in essence, you cannot change yourself fundamentally.  So if some things go wrong, it's destigmatized, not your fault. It's like, you know, if you have the flu, you're not going to blame anyone for having the flu.

In this way, you're not blaming anyone for having depression or having OCD. And you're not blaming the family or whatever. You're just, okay, this is a problem we have now that you have at this stage of your life we're going to try and treat it.

And looking at it from the point of view of biology, not just the brain but the rest of the body, which is often neglected, I think psychiatric disorders are the brain is involved, but actually, the whole body is involved.

When someone is feeling depressed, you're feeling tired, you have more pain you know your whatever, so this is also is an avenue of treatment and also for people to understand what's wrong with them and to explain and to let's say what you try to achieve as a doctor is to form a let's say an alliance between you and your patient and treating the complaints.

That's how you that's the alliance that you try to make. I think this can be a way in this can help, let's say to form such an alliance.


Dr Elisabetta Burchi 23:38

I think you touch upon the main big topics so that there are in psychiatry the fact that for these disorders absolutely biology it is just one component. Mental disorders are not just disorders of the brain but disorders in which the brain is necessarily involved. Right

And this paradoxically gives the freedom to allow.  So we can treat them, you know, instead of saying it's my fault I'm guilty because I have this, I am responsible for having these disorders, accepting that there are biological underpinnings. It doesn't mean saying that the other human being is determined but means that we can treat this as a disorder. And then there is a not the human factor the personality that is another thing.  That is to be it's not touched by these disorders like no using treatments does not affect the personality.

Because there is also all this misunderstanding that if we use the drugs or this kind of treatment, then something is going to happen, I'm not myself anymore. Now, this is another misunderstanding, and then these other facets the inter systemic quality of these disorders. So this is true for all medicine, not only for psychiatry, mainly for psychiatry. Maybe because it's the more complex field than all, but everything is interconnected, and when we treat something, we need to take into account they're all individuals. So we know that depression is also an inflammatory disease.

Right, so the neuromodulation techniques actually with the stimulation of the vagus nerve is helpful probably also because we are going to affect the inflammatory response. Right.


Dr Koen Schruers 25:53

Yeah, that's impossible maybe to add a little comment on what you said on personality. Because that's something that patients ask me before they enter into the program of the brain stimulation often, "Are you going to change who I am by putting electrodes in my brain?".

And there's a really interesting study on that from the group of Damian Denis in Amsterdam who looked into this and did qualitative interviews with people who had received brain stimulation for OCD. Asking them has this happened? Have you changed? Is your personality changed? Who are you, who were you before, who are you now? And the majority actually says that "Well, the way I am now after surgery, this is closer to the person I really am and who I want to be this is who I am not with the disorder.

I think I find it very reassuring I always tell my patients about this, and I'm very happy that they did this study. It's rare, but I think for this, you need qualitative methods, and they did it really well, and it's a beautiful paper that I often cite. So as a side note, I think that's been quite interesting.


Dr Elisabetta Burchi 27:00

That's great, that's fantastic. I think we can say goodbye to ourselves to each other now we may stay here for hours and hours and if you are available, we will contact you for other topics. And that was a fantastic conversation. Thank you so much, Professor Schruers and see you soon.


Dr Koen Schruers 27:29

You're very welcome. Thank you

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