Emerging Biomarkers in Movement Disorders

In this episode, Lyell K. Jones Jr, MD, FAAN, speaks with Michael S. Okun, MD, FAAN, who served as the guest editor of the August 2025 Movement Disorders issue. They provide a preview of the issue, which publishes on August 1, 2025.

Dr. Jones is the editor-in-chief of Continuum: Lifelong Learning in Neurology® and is a professor of neurology at Mayo Clinic in Rochester, Minnesota.

Dr. Okun is the director at Norman Fixel Institute for Neurological Diseases and distinguished professor of neurology at University of Florida in Gainesville, Florida.

Additional Resources

Read the issue: continuum.aan.com

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Continuum® Aloud (verbatim audio-book style recordings of articles available only to Continuum® subscribers): continpub.com/Aloud

More about the American Academy of Neurology: aan.com

Social Media

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@ContinuumAAN

Host: @LyellJ

Guest: @MichaelOkun

Full episode transcript available here:

Dr Jones: Our ability to move through the world is one of the essential functions of our nervous system. Gross movements like walking ranging down to fine movements with our eyes and our hands, our ability to create and coordinate movement is something many of us take for granted. So what do we do when those movements stop working as we intend? Today I have the opportunity to speak with one of the world's leading experts on movement disorders, Dr Michael Okun, about the latest issue of Continuum on Movement Disorders.

Dr Jones: This is Dr Lyell Jones, Editor-in-Chief of Continuum. Thank you for listening to Continuum Audio. Be sure to visit the links in the episode notes for information about subscribing to the journal, listening to verbatim recordings of the articles, and exclusive access to interviews not featured on the podcast.

Dr Jones: This is Dr Lyle Jones, Editor-in-Chief of Continuum: Lifelong Learning in Neurology. Today, I'm interviewing Dr Michael Okun, who is Continuum's guest editor for our latest issue on movement disorders. Dr Okun is the Adelaide Lackner Distinguished Professor of Neurology at the University of Florida in Gainesville, where he's also the director of the Norman Fixel Institute for Neurological Diseases. Dr Okun, welcome, and thank you for joining us today. Why don't you introduce yourselves to our listeners? 

Dr Okun: It's great to be here today. And I'm a neurologist. Everybody who knows me knows I'm pretty simple. I believe the patient's the sun and we should always orbit around the person with disease, and so that's how I look at my practice. And I know we always participate in a lot of research, and I've got a research lab and all those things. But to me, it's always the patients and the families first. So, it'll be great to have that discussion today. 

Dr Jones: Yeah, thank you for that, Dr Oaken. Obviously, movement disorders is a huge part of our field of neurology. There are many highly prevalent conditions that fit into this category that most of our listeners will be familiar with: idiopathic Parkinson's disease, essential tremor, tic disorders and so on. And having worked with trainees for a long time, it's one of the areas that I see a lot of trainees gravitate to movement disorders. And I think it's in part because of the prevalence; I think it's in part because of the diversity of the specialty with treatment options and DBS and Botox. But it's also the centrality of the neurologic exam, right? That's- the clinical examination of the patient is so fundamental. And we'll cover a lot of topics today with some questions that I have for you about biomarkers and new developments in the field. But is that your sense too, that people are drawn to just the old-fashioned, essential focus on the neurologic encounter and the neurologic exam?

Dr Okun: I believe that is one of the draws to the field of movement. I think that you have neurologists from all over the world that are really interested and fascinated with what things look like. And when you see something that's a little bit, you know, off the normal road or off the normal beaten path… and we are always curious. And so, I got into movement disorders, I think, accidentally; I think even as a child, I was looking at people who had abnormal movements and tremors and I was very fascinated as to why those things happened and what's going on in the brain. And, you know, what are the symptoms and the signs. And then later on, even as my own career developed, that black bag was so great as a neurologist. I mean, it makes us so much more powerful than any of the other clinicians---at least in my biased opinion---out on the wards and out in the clinic. And, you know, knowing the signs and the symptoms, knowing how to do a neurological examination and really walking through the phenomenology, what people look like, you know, which is different than the geno- you know, the genotypes, what the genes are. What people look like is so much more important as clinicians. And so, I think that movement disorders is just the specialty for that, at least in my opinion.

Dr Jones: And it helps bring it back to the patient. And that's something that I saw coming through the articles in this issue. And let's get right to it. You've had a chance to review all these articles on all these different topics across the entire field of movement disorders. As you look at that survey of the field, Dr Okun, what do you think is the most exciting recent development for patients with movement disorders? 

Dr Okun: I think that when you look across all of the different specialties, what you're seeing is a shift. And the shift is that, you know, a lot of people used to talk in our generation about neurology being one of these “diagnose and adios” specialties. You make the diagnosis and there's nothing that you can do, you know, about these diseases. And boy, that has changed. I mean, we have really blown it out of the water. And when you look at the topics and what people are writing about now and the Continuum issue, and we compare that the last several Continuum issues on movement disorders, we just keep accumulating a knowledge base about what these things look like and how we can treat them. And when we start thinking about, you know, all of the emergence of the autoimmune disorders and identifying the right one and getting something that's quite treatable. Back in my day, and in your day, Lyle, we saw these things and we didn't know what they were. And now we have antibodies, now we can identify them, we can pin them down, and we can treat many of them and really change people's lives. And so, I'm really impressed at what I see in changes in identification of autoimmune disorders, of channelopathies and some of the more rare things, but I'm also impressed with just the fundamental principles of how we're teaching people to be better clinicians in diseases like Parkinson’s, Huntington's, ataxia, and Tourette. And so, my enthusiasm for this issue of Continuum is both on, you know, the cutting edge of what we're seeing based on the identification on our exams, what we can do for these people, but also the emergence of how we're shifting and providing much better care across a continuum for folks with basal ganglia diseases.

Dr Jones: Yeah, I appreciate that perspective, Dr Okun. One of the common themes that I saw in the issue was with these new developments, right, when you have new tools like new diagnostic biomarker tools, is the question of if and when and how to integrate those into daily clinical practice, right? So, we've had imaging biomarkers for a while, DAT scans, etc. For patients with idiopathic Parkinson disease, one of the things that I hear a lot of discussion and controversy about are the seed amplification assays as diagnostic biomarkers. What can you tell us about those? Are those ready for routine clinical use yet? 

Dr Okun: I think the main bottom-line point for folks that are out there trying to practice neurology, either in general clinics or even in specialty clinics, is to know that there is this movement toward, can we biologically classify a disease? One of the things that has, you know, really accelerated that effort has been the development of these seed amplification assays, which---in short for people who are listening---are basically, we “shake and bake” these things. You know? We shake them for like 20 hours and we use these prionlike proteins, and we learn from diseases like prion disease how to kind of tag these things and then see, do they have degenerative properties? And in the case of Parkinson's disease, we're able to do this with synuclein. That is the idea of a seed amplification assay. We're able to use this to see, hey, is there synuclein present or not in this sample? And people are looking at things like cerebrospinal fluid, they're looking at things like blood and saliva, and they're finding it. The challenge here is that, remember- and one of the things that's great about this issue of Continuum is, remember, there are a whole bunch of different synucleinopathies. So, Dr Jones, it isn't just Parkinson's disease. So, you've got Parkinson's disease, you've got Lewy body, you know, and dementia with Lewy bodies. You've got, you know, multiple system atrophy is within that synucleinopathy, you know, group primary autonomic failure… so not just Parkinson's disease. And so, I think we have to tap the brakes as clinicians and just say, we are where we are. We are moving in that direction. And remember that a seed amplification assay gives you some information, but it doesn't give you all the information. It doesn't forgive you looking at a person over time, examining them in your clinic, seeing how they progress, seeing their response to dopamine- and by the way, several of these genes that are associated with Parkinson; and there's, you know, less than 20% of Parkinson is genetic, but several of these genes, in a solid third---and in some cases, in some series, even more---miss the synuclein assay, misses, you know, the presence of a disease like Parkinson's disease. And so, we have to be careful in how we interpret it. And I think we're more likely to see over time a gemish: we're going to smush together all this information. We're going to get better with MRIs. And so, we're actually doing much better with MRIs and AI-based intelligence. We've got DAT scans, we've got synuclein assays. But more than anything, everybody listening out there, you can still examine the person and examine them over time and see how they do over time and see how they do with dopamine. And that is still a really, really solid way to do this. The synuclein assays are probably going to be ready for prime time more in choosing and enriching clinical trials populations first. And you know, we're probably 5, 10 years behind where Alzheimer's is right now. So, we'll get there at some point, but it's not going to be a silver bullet. I think we're looking at these are going to be things that are going to be interpreted in the context for a clinician of our examination and in the context of where the field is and what you're trying to use the information for.

Dr Jones: Thank you for that. And I think that's the general gestalt I got from the articles and what I hear from my colleagues. And I think we've seen this in other domains of neurology, right? We have the specificity and sensitivity issues with the biomarkers, but we also have the high prevalence of copathology, right? People can have multiple different neurodegenerative problems, and I think it gets back to that clinical context, like you said, following the patient longitudinally. That was a theme that came out in the idiopathic Parkinson disease article. And while we're on Parkinson disease, you know, the first description of that was what, more than two hundred years ago. And I think we're still thinking about the pathophysiology of that disorder. We understand risk factors, and I think many of our listeners would be familiar with those. But as far as the actual cause, you know, there's been discussion in recent years about, is there a role of the gut microbiome? Is this a prionopathic disorder? What's your take on all of that? 

Dr Okun: Yeah, so it's a great question. It's a super-hot area right now of Parkinson. And I kind of take this, you know, apart in a couple of different ways. First of all, when we think about Parkinson disease, we have to think upstream. Like, what are the cause and causes? Okay? So, Parkinson is not one disease, okay? And even within the genes, there's a bunch of different genes that cause it. But then we have to look and say, well, if that's less than 20% depending on who's counting, then 80% don't have a single piece of DNA that's closely associated with this syndrome. And so, what are we missing with environment and other factors? We need to understand not what happens at the end of the process, not necessarily when synuclein is clumping- and by the way, there's a lot of synuclein in the brains normally, and there's a lot of Tau in people's brains who have Parkinson as well. We don't know what we don't know, Dr Jones. And so when we begin to think about this disease, we've got to look upstream. We've got to start to think, where do things really start? Okay? We've got to stop looking at it as probably a single disease or disorder, and it's a circuit disorder. And then as we begin to develop and follow people along that pathway and continuum, we're going to realize that it's not a one-size-fits-all equation when we're trying to look at Parkinson. By the way, for people listening, we only spend two to three cents out of every dollar on prevention. Wouldn't prevention be the best cure, right? Like, if we were thinking about this disease. And so that's something that we should be, you know, thinking about. And then the other is the Global Burden of Disease study. You know, when we wrote about this in a book called Ending Parkinson's Disease, it looked like Parkinson's was going to double by 2035. The new numbers tell us it's almost double to the level that we expected in 2035 in this last series of numbers. So, it's actually growing much faster. We have to ask why? Why is it growing faster? And then we have lots of folks, and even within these issues here within Continuum, people are beginning to talk about maybe these environmental things that might be blind spots. Is it starting in our nose? Is it starting in our gut? And then we get to the gut question. And the gut question is, if we look at the microbiomes of people with Parkinson, there does seem to be, in a group of folks with Parkinson, a Parkinson microbiome. Not in everyone, but if you look at it in composite, there seems to be some clues there. We see changes in Lactobacillus, we see some bacteria going up that are good, some bacteria going down, you know, that are bad. And we see flipping around, and that can change as we put people on probiotics and we try to do fecal microbiota transplantations- which, by the way, the data so far has not been positive in Parkinson's. Doesn't mean we might not get there at some point, but I think the main point here is that as we move into the AI generation, there are just millions and millions and millions of organisms within your gut. And it's going to take more than just our eyes and just our regular arithmetic. You and I probably know how to do arithmetic really well, but this is, like, going to be a much bigger problem for computers that are way smarter than our brains to start to look and say, well, we see the bacteria is up here. That's a good bacteria, that's a good thing or it's down with this bacteria or this phage or there's a relationship or proportion that's changing. And so, we're not quite there. And so, I always tell people---and you know, we talk about the sum in the issue---microbiomes aren't quite ready for prime time yet. And so be careful, because you could tweak the system and you might actually end up worse than before you started. So, we don't know what we don't know on this issue. 

Dr Jones: And that's a great point. And one of the themes they're reading between the lines is, we will continue to work on understanding the bio-pathophysiology, but we can't wait until that day to start managing the risk factors and treating patients, which I think is a good point. And if we pivot to treatment here a little bit, you know, one of the exciting areas of movement disorders---and really neurology broadly, I think movement disorders has led the field in many ways---is bioelectronic therapy, or what one of my colleagues taught me is “electroceutical therapy”, which I think is a wonderful term. Dr Okun, when our listeners are hearing about the latest in deep brain stimulation in patients who have movement disorders, what should they know? What are the latest developments in that area with devices?

Dr Okun: Yeah. So, they should know that things are moving rapidly in the field of putting electricity into the brain. And we're way past the era where we thought putting a little bit of electricity was snake oil. We know we can actually drive these circuits, and we know that many of these disorders---and actually, probably all of the disorders within this issue of Continuum---are all circuit disorders. And so, you can drive the circuit by modulating the circuit. And it's turned out to be quite robust with therapies like deep brain stimulation. Now, we're seeing uses of deep brain stimulation across multiple of these disorders now. So, for example, you may think of it in Parkinson's disease, but now we're also seeing people use it to help in cases where you need to palliate very severe and bothersome chorea and Huntington's disease, we're seeing it move along in Tourette syndrome. We of course have seen this for various hyperkinetic disorders and dystonias. And so, the main thing for clinicians to realize when dealing with neuromodulation is, take a deep breath because it can be overwhelming. We have a lot of different devices in the marketplace and no matter how many different devices we have in the marketplace, the most important thing is that we get the leads. You know, where we're stimulating into the right location. It's like real estate: location, location, location, whether you've got a lead that can steer left, right, up, down and do all of these things. Second, if you're feeling overwhelmed because there are so many devices and so many settings, especially as we put these leads in and they have all sorts of different, you know, nodes on them and you can steer this way and that way, you are not alone. Everybody is feeling that way now. And we're beginning to see AI solutions to that that are going to merge together with imaging, and then we're moving toward an era of, you know, should I say things like robotic programming, where it's going to be actually so complicated as we move forward that we're going to have to automate these systems. There's no way to get this and scale this for all of the locales within the United States, but within the entire world of people that need these types of devices and these therapies. And so, it's moving rapidly. It's overwhelming. The most important thing is choosing the right person. Okay? For this, with multidisciplinary teams, getting the lead in the right place. And then all these other little bells and whistles, they're like sculpting. So, if you think of a sculpture, you kind of get that sculpture almost there. You know, those little adds are helping to maybe make the eyes come out a little more or the facial expression a little bit better. There's little bits of sculpting. But if you're feeling overwhelmed by it, everybody is. And then also remember that we're starting to move towards some trials here that are in their early stages. And a lot of times when we start, we need more failures to get to our successes. So, we're seeing trials of people looking at, like, oligo therapies and protein therapies. We're seeing CRISPR gene therapies in the laboratory. And we should have a zero tolerance for errors with CRISPR, okay? we still have issues with CRISPR in the laboratory and which ones we apply it to and with animals. But it's still pretty exciting when we're starting to see some of these therapies move forward. We're going to see gene therapies, and then the other thing we're going to see are nano-therapies. And remember, smaller can be better. It can slip across the blood brain barrier, you have very good surface area-to-volume ratios, and we can uncage drugs by shining things like focused ultrasound beams or magnets or heat onto these particles to turn them on or off. And so, we're seeing a great change in the field there. And then also, I should mention: pumps are coming and they're here. We're getting pumps like we have for diabetes and neurology. It's very exciting. It's going to be overwhelming as everybody tries to learn how to do this. So again, if you're feeling overwhelmed, so am I. Okay? But you know, pumps underneath the skin for dopamine, pumps underneath the skin for apomorphine. And that may apply to other disorders and not just Parkinson as we move along, what we put into those therapies. So, we're seeing that age come forward. And then making lesions from outside the brain with focused ultrasound, we're starting to get better at that. Precision is less coming from outside the brain; complications are also less. And as we learn how to do that better, that also can provide more options for folks. So, a lot of things to read about in this issue of Continuum and a lot of really interesting and beyond, I would say, you know, the horizon as to where we're headed. 

Dr Jones: Thank you for that. And it is a lot. It can be overwhelming, which I guess is maybe a good reason to read the issue, right? I think that's a great place to end and encourage our listeners to pick up the issue. And Dr Okun, I want to thank you for joining us today. Thank you for such a great discussion on movement disorders. I learned a lot. I'm sure our listeners will as well, given the importance of the topic, your leadership in the field over many years. I'm grateful that you have put this issue together. So, thank you. And you're a busy person. I don't know how we talked you into doing this, but I'm really glad that we did. 

Dr Okun: Well, it's been my honor. And I just want to point out that the whole authorship panel that agreed to write these articles, they did all the work. I'm just a talking head here, you know, telling you what they did, but they're writing, and the people that are in the field are really, you know, leading and helping us to understand, and have really put it together in a way that's kind of helped us to be better clinicians and to impact more lives. So, I want to thank the group of authors, and thank you, Dr Jones.

Dr Jones: Again, we've been speaking with Dr Michael Okun, guest editor of Continuum's most recent issue on movement disorders. Please check it out. And thank you to our listeners for joining today.

Dr Monteith: This is Dr Teshamae Monteith, Associate Editor of Continuum Audio. If you've enjoyed this episode, you'll love the journal, which is full of in-depth and clinically relevant information important for neurology practitioners. Use the link in the episode notes to learn more and subscribe. Thank you for listening to Continuum Audio.