Dr. Margarita Fedorova outlines how genetic, environmental, and pathological factors interact in Parkinson's disease and what this means for patient counseling.

Show citation:

Blauwendraat C, Morris HR, Van Keuren-Jensen K, Noyce AJ, Singleton AB. The temporal order of genetic, environmental, and pathological risk factors in Parkinson's disease: paving the way to prevention. Lancet Neurol. 2025;24(11):969-975. doi:10.1016/S1474-4422(25)00271-6

Show transcript:

Dr. Margarita Federova:

Welcome to Neurology Minute. My name is Margarita Fedorova, and I'm a neurology resident at the Cleveland Clinic. Today we're exploring a framework for understanding how genetic, environmental, and pathological factors interact in Parkinson's disease and what this means for how we counsel our patients.

A personal view paper by Blauwendraat and colleagues, published in The Lancet Neurology in September 2025, addresses a critical question. We've identified over 100 genetic loci for Parkinson's, but how do they act?

The common saying is genetics loads the gun and environment pulls the trigger, but this paper suggests the relationship may be more complex. The key tool here is alpha-synuclein seeding amplification assays or SAAs.

These detect misfolded alpha-synuclein protein in cerebrospinal fluid. Over 90% of Parkinson's patients test positive for misfolded alpha-synuclein using this assay. But here's what's notable. 2% to 16% of neurologically healthy older adults also test positive with prevalence increasing with age.

This means there are more asymptomatic people with detectable alpha-synuclein pathology than people with actual Parkinson's disease. Most of these asymptomatic individuals will never develop symptoms. This raises an important question. What determines who converts to a disease and who doesn't?

By integrating SAA results with genetic data, researchers can examine whether genetic factors drive initial protein misfolding or whether they modulate the response to pathology triggered by environmental or random events.

Preliminary data suggests polygenic risk scores don't strongly associate with SAA positivity in healthy older adults. In other words, people with high genetic risk for Parkinson's aren't necessarily more likely to have misfolded alpha-synuclein if they're healthy.

This suggests most Parkinson's genetic risk factors may not be causing initial misfolding. Instead, they may be determining what happens afterward, such as whether the pathology progresses to clinical disease.

LRRK2 mutations support this model. About 33% of LRRK2 related Parkinson's patients are SAA-negative compared to only 7% in sporadic disease. This means many people with LRRK2 mutations develop Parkinson's without the typical alpha-synuclein pathology.

LRRK2 mutations also show varied pathology. Sometimes alpha-synuclein, sometimes tau, sometimes neither. This suggests LRRK2 may modulate responses to different initiating events rather than directly causing protein misfolding.

What does this mean for us as clinicians? Asymptomatic SAA-positive individuals could represent a window for intervention. If we can understand what protects them from converting to disease or what triggers that conversion, we could enable earlier identification of at risk individuals and potentially intervene before symptoms develop.

The authors call for large scale studies using SAAs in older populations, combined with genetic analysis and longitudinal follow-up. By integrating pathological biomarkers with genetic and environmental data, we can better understand the temporal sequence of events in development of Parkinson's.

This approach could fundamentally change how we think about disease prevention and early intervention, potentially allowing us to identify at risk individuals before symptoms appear and develop targeted prevention strategies.

That's your neurology minute for today. Keep exploring, and we'll see you next time.

If you want to read more, please find the paper by Cornelis Blauwendraat et al titled The Temporal Order of Genetic, Environmental and Pathological Risk Factors in Parkinson's Disease: Paving the Way to Prevention, published online in September 2025 in Lancet Neurology.

Dr. Tesha Monteith highlights the American Headache Society's position statement, which advocates for migraine screening in girls and women.

Show citation:

Schwedt TJ, Starling AJ, Ailani J, et al. Routine migraine screening as a standard of care for Women's health: A position statement from the American Headache Society. Headache. Published online December 10, 2025. doi:10.1111/head.70023

Show transcript:

Dr. Tesha Monteith:

Hi, this is Tesha Monteith with the Neurology Minute. Welcome back to our Women's Health and Headache Medicine series. Did you know the American Headache Society recently published a position statement to encourage screening for migraine in girls and women? The position statement was based on review of the literature to establish if migraine met standards for screening in subpopulations and to assess appropriate screening tools.

The team achieved consensus, agreeing that migraine, due to its prevalence, morbidity, high cost, availability of screening methods and treatments, does meet criteria to justify screening for girls and women. The panel suggested that migraine should be screened annually as part of women's preventative care with tools like ID-Migraine. ID-Migraine is a self-administered three-question survey that has been validated in primary care settings. Patients answer yes or no to having the following with headache over the past three months.

Patients are asked if headaches limited your ability to work, study, or do what they need to do on at least one day. You felt nauseated or sick to your stomach. Light bothered you a lot more than when you don't have headaches. Answering at least two of the three is positive for migraine. The panel acknowledged certain barriers, but they ultimately emphasize the overwhelming benefits of screening for migraine in women and children. Although the focus is for females, they recognize benefits in boys and men as well. Check out this position statement. It's a great read. This is Tesha Monteith. Thank you for listening to the Neurology Minute.

In the final installment of this series, Dr. Justin Abbatemarco and Dr. Divyanshu Dubey discuss the latest findings and some non-occupational exposures.

Show citation:

Hinson SR, Gupta P, Paramasivan NK, et al. Neural synaptic vesicle autoimmunity following aerosolized porcine neural tissue exposure: insights into autoimmune inflammatory polyradiculoneuropathy. EBioMedicine. 2025;122:106053. doi:10.1016/j.ebiom.2025.106053

Show transcript:

Dr. Justin Abbatemarco:

Hello, and welcome back. This is Justin Abbatemarco. I'm here with Divyanshu Dubey, discussing his article, Neural Synaptic Vesicle Autoimmunity Following Aerosolized Porcine Neural Tissue Exposure: Insights Into Autoimmune Inflammatory Polyradiculoneuropathy.

Div, maybe we could talk about non-occupational exposures? I think many of us don't see this cohort of patients commonly, but I really think this helps inform care, beyond just this specific occupational exposure. What did you guys find in your work?

Dr. Divyanshu Dubey:

So, one of the inspirations for this study was driven by the phenotypic characterization of patients who were described in this 2010 paper, which is somewhat similar to some of the patients I currently see in my clinic who don't seem to meet GBS or CIDP criteria. But, based on their MRI findings, based on their CSF studies, the EMG nerve conduction studies, they seem to have this polyradiculoneuropathy presentation, often presenting with asymmetric disease onsets, starting on one leg and then sometimes transitioning to the other side.

In some cases, even a non-length dependent pattern with sort of proximal cervical brachial nerve root plexus involvements, which don't really seem to have a blood test, or a biomarker right now. Currently, many of these cases are a diagnosis of exclusion. I was thinking if there's a biomarker that we can identify from this 2006 to 2008 unfortunate event, that might actually help us diagnose these patients.

So, once we identified synaptophysin and GAP43 antibodies in the swine abattoir cohort, I went back to our storages of these patients with other inflammatory polyradiculoneuropathy, and found about 5% of these patients from a large cohort of close to 300 patients, did have these antibody biomarkers.

Some of these patients had paraneoplastic trigger, where we had patients with neuroendocrine tumors, or hematological malignancies mounting a response to these antibodies. But a good chunk of these patients we did not truly understand, or know what the triggers were. That might be a potential for future studies, as we expand our cohort of these antibodies, as well as study further the phenotypic characterization of these cases.

Dr. Justin Abbatemarco:

Yeah, there's just so much there, really helping to inform future clinical care outside of this very specific occupational exposure. And then, as we talked about in the podcast, I think really helping to think through how neurological autoimmune diseases develop. So, just really exciting work.

We really appreciate you coming on, sharing this. We're excited for how this evolves over the coming years.

Dr. Divyanshu Dubey:

Thank you, Justin.

In part one of this two-part series, Dr. Justin Abbatemarco and Dr. Divyanshu Dubey discuss the original patient cohort with occupational exposure, what motivated this line of research, and the key findings from the initial workup.

Show citation:

Hinson SR, Gupta P, Paramasivan NK, et al. Neural synaptic vesicle autoimmunity following aerosolized porcine neural tissue exposure: insights into autoimmune inflammatory polyradiculoneuropathy. EBioMedicine. 2025;122:106053. doi:10.1016/j.ebiom.2025.106053

Show transcript:

Dr. Justin Abbatemacro:

Hello and welcome. This is Justin Abbatemacro. And I'm here with Divyanshu Dubey to discuss his article published in eBiomedicine, Neurosynaptic Vessel Autoimmunity Following Aerosolized Porcine Neural Tissue Exposure: Insight into Autoimmune Inflammatory Polyradicular Neuropathy.

Dr. Justin Abbatemacro:

Div is a professor of neurology at the Mayo Clinic, and we just finished our interview, which I would encourage everyone to check out. Div, maybe we could talk about the original cohort with this occupational exposure, what inspired you to do this work and then what did you find with that initial workup?

Dr. Divyanshu Dubey:

As recounted in our paper, this story began in 2006 to 2008, when a group of swine abattoir workers developed a striking neurological syndrome. These people were previously healthy and suddenly developed severe neuropathic pain, tingling, and variable weakness. The localization stood out, these cases were initially identified by Dan Lachance, who characterized these patients having an autoimmune neuropathy, which was further phenotypically characterized by the work done by Dr. Dyck, calling these inflammatory polyradicular neuropathy based on their nerve root plexus and proximal nerve collisions. And interestingly, a lot of work done back then by Dr. Lennon showed these patients had a unique synaptic staining pattern suggesting there was an underlying antibody driving this disease process. So as I joined the neuroimmunology lab a few years ago, this was one of the areas I wanted to go back and study, not only to find this mystery biomarker which caused the disease in these patients, but also to try and understand how this can help.

Dr. Justin Abbatemacro:

Yeah. I think my takeaway is be curious, right? You hear the story, you see this pattern. Be curious and investigate, and it takes a team or a village to do it.

Dr. Divyanshu Dubey:

100%. So observation, communication between, as you said, a team or a village with like-minded, passionate individuals is one of the successes of many of our discoveries, not just this one in this biomarker space.

Dr. Divyanshu Dubey:

So the technique we use for discovery of these biomarkers was called a phage display where we use the archive sera to test from these patients, the swine abattoir worker patients with autoimmune polyradicular neuropathy. And we ended up finding two dominant antigens, which was synaptophysin and GAP-43, which were present in majority of these cases.

Dr. Justin Abbatemacro:

Please come back and check out part two where we discuss the latest findings and maybe some non-occupational exposures. And check out the podcast. Thanks.

In the second installment of this two-part series, Drs. Stacey Clardy, Ayush Gupta, and Kuntal Sen discuss the most practical testing approach to minimize both under‑ and over‑testing for these disorders.

Show citation:

Gupta A, Sahjwani D, Kahn I, Gombolay GY, Sen K. Monogenic Mimics of Neuroinflammatory Phenotypes in Children and Young Adults: An Evolving Landscape. Neurol Genet. 2025;11(6):e200326. Published 2025 Nov 25. doi:10.1212/NXG.0000000000200326

Show transcript:

Dr. Stacey Clardy:

Hi, this is Stacey Clardy from the Salt Lake City VA in the University of Utah. For a two-part podcast series this week, I've been speaking with Ayush Gupta, from the University of Nebraska Medical Center, and Kuntal Sen, from Children's National Hospital in Washington, DC about monogenic disorders that mimic neuroinflammatory disease. There are a lot of them, and they are no doubt sitting in our clinics waiting to be recognized.

Ayush, for the minute, once a neurologist starts suspecting one of these disorders, what's the most practical testing strategy to avoid both under and over-testing for these disorders?

Dr. Ayush Gupta:

I think the most practical strategy is to write down all the phenotypic symptoms that you think could be related, put that exact information into a genetic testing panel that will be suitable. Or, if possible, try to do a broader genetic testing such as whole genome sequencing, and make yourself equipped to be able to analyze the results that you get from the testing.

Dr. Stacey Clardy:

I hear you saying, at least when you're thinking about this, be a bit of a lumper. As we covered in the podcast, if we are going to pursue that genetic testing, it is absolutely critical that we share that list with the interpreting geneticist because that determines how they score variants and how they rate them as related or not.

Please take a listen to that two-part podcast series, where we get into all these details. I walked away with a great framework on how to do better in terms of picking these disorders out. Again, the paper that accompanies the two-part podcast series is in Neurology Genetics. It's a comprehensive review and called Monogenic Mimics of Neuroinflammatory Phenotypes in Children and Young Adults in Evolving Landscape.

Thank you, Ayush.

Dr. Ayush Gupta:

Thank you so much.

Dr. Aaron Zelikovich discusses the utility of neurofilament light chain as a serum biomarker in peripheral neuropathy.

Show citation:

Karam C. Clinical Utility of Serum Neurofilament Light Chain in Peripheral Neuropathy. Muscle Nerve. 2026;73(1):86-92. doi:10.1002/mus.70073

Show transcript:

Dr. Aaron Zelikovich:

Welcome to today's neurology minute. My name is Aaron Zelikovich, a neuromuscular specialist at Lenox Hill Hospital in New York City. Today, we will discuss a recent article on the utility of neurofilament light chain as a serum biomarker in peripheral neuropathy. It has been studied in other neurological diseases like ALS and multiple sclerosis, as in the 2024 study by Robert Fox et al, which highlighted the limitations of serum neurofilament light chain in patients with multiple sclerosis, since the elevation was inconsistent and tended to occur weeks after MRI changes, and was really only found to be helpful in certain clinical situations. The study we highlight today is a single-center retrospective study that highlights the opportunities and limitations of using serum neurofilament light chain as a biomarker to monitor treatment response and peripheral neuropathy.

Serum neurofilament light chain has been shown as an indicator of neuronal injury in both central and peripheral nervous system disease that has been associated with axonal injury or degeneration. It is now commercially available. The authors in this study provide a real-world single-center retrospective study that looked at various forms of peripheral neuropathy over 12 months. Patients had to be evaluated and meet criteria for peripheral neuropathy with either genetic testing, nerve conduction studies, and/or clinical exams. Neuropathies included TTR amyloid, vasculitis, CMT, CIDP, GBS, and anti-MAG neuropathy.

Patients with TTR amyloid who were treatment naive and had elevated serum neurofilament light chain showed a reduction in neurofilament light chain levels with treatment. Additionally, patients with CIDP who were treatment naive with elevated serum neurofilament light chain also showed a reduction in neurofilament light chain levels with treatment. All patients with idiopathic peripheral neuropathy had normal serum neurofilament light chain levels. However, serum neurofilament light chain can vary in patients based on age, if they have diabetes, renal dysfunction, and body weight. And this makes it really challenging to interpret it in an isolated setting.

Serum neurofilament light chain is a new biomarker for peripheral neuropathies. It can be a supplemental tool in the appropriate clinical context. Future studies are needed to identify its potential to be used as a treatment response biomarker in neuropathies like CADP, GBS, and TTR amyloid. Thank you so much, and have a wonderful day.

Dr. Tesha Monteith discusses the different forms of menstrual migraines.

Show transcript:

Dr. Tesha Monteith:

Hi, this is Tesha Monteith with the Neurology Minute. Welcome to our series on headache medicine and women's health. I want to start off this series with a discussion on menstrual migraine. Menstrual migraine is considered more frequent, more severe, and is associated with most migraine-associated symptoms with the exception of aura. The pathophysiology is linked to the effects of estrogen withdrawal and the impacts on the trigeminal vascular system. Do check out a recent paper by Pan and colleagues published just in neurology in November showing a robust hypothalamic activation prior to the headache phase in patients with menstrual migraine compared to controls.

Now, there are two forms of menstrual migraine recognized in the International Classification of Headache Disorders III. First is menstrually related migraine which consists of attacks that occurred during the perimenstrual window. That's day one of menses plus or minus two days and at least two of three menstrual cycles and during additional times outside of the window. Perimenstrual migraine attacks occur exclusively during the perimenstrual window and is much less common than menstrually related migraine.

A key point is that there's a predictable timing with each cycle, yet the condition is still very much underdiagnosed. Advise your patients to use an e-diary to improve the diagnosis and hopefully reduce disability. This is Tesha Monteith. Thank you for listening to the Neurology Minute.