Your Brain On... Parkinson's (2025)

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Nov 26, 2025

Joining the conversation are Rachel Dolhun, Senior VP at The Michael J. Fox Foundation, and Michael Okun, a movement disorders specialist. They discuss the complex spectrum of Parkinson's symptoms, both motor and non-motor, and intriguing early detection signs like changes in smell. The impact of genetics and environmental factors is explored, alongside the overlap with Alzheimer's. They emphasize the crucial role of lifestyle—nutrition and exercise—in managing symptoms and preventing onset, offering hope for future research advancements.

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INSIGHT

Parkinson's Is A Whole-Body Condition

Parkinson's affects movement and many non-motor systems across the whole body, not just the brain's motor circuits.
Rachel Dolhun emphasizes symptoms like mood, sleep, constipation, and cognition alongside tremor and stiffness.

INSIGHT

Genes Are Clues, Not Destiny

Genetics contribute variably: a few high-effect genes exist, but most Parkinson's arises from many small genetic risks plus environment and aging.
Matthew Farrer and Michael Okun note incomplete penetrance and complex gene–environment interactions.

ANECDOTE

The Nurse Who Smelled Parkinson's

Joy Milne, a nurse with heightened smell, detected Parkinson's by body odor and inspired trained dogs and research into olfactory markers.
Matthew Farrer uses this to illustrate early, noninvasive detection possibilities like smell and REM sleep behavior disorder.

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From 18th century London to the promise of a global cure: the 200-year history of Parkinson's disease.

To mark the release of our 'Ask the MD' conversation with The Michael J. Fox Foundation for Parkinson's Research, and to welcome a new influx of listeners, we're sharing one of our very first episodes, first aired in August 2024.

Watch our full 'Ask the MD' interview, focused on lifestyle strategies for boosting brain health, on the foundation's website: https://www.michaeljfox.org/news/lifestyle-strategies-boost-brain-health-ask-md-video

Parkinson's, a neurodegenerative disorder most commonly characterized by tremors and other motor symptoms, is so complex, many medical professionals are starting to classify it as a group of diseases, rather than a single disease.

In this episode, we explain those complexities, including:

• The motor symptoms (e.g. cogwheel rigidity, bradykinesia) and non-motor symptoms (e.g. depression, sleep disorders)

• How the industrial revolution may have brought about environmental factors which contribute to Parkinson's

• The differences and similarities between Parkinson's and other neurodegenerative diseases, like Alzheimer's

• How Parkinson's manifests in our brains

• Why one nurse was able to detect Parkinson's through smell

• The neurogenetics of Parkinson's, and the ethical quandaries of evolving genetic technology

• Why lifestyle — nutrition, exercise, etc. — is so key to preventing and managing Parkinson's

Joining us for this extensive conversation are three incredible guests:

• Dr. Rachel Dolhun, Senior Vice President of Medical Communications at The Michael J. Fox Foundation for Parkinson's Research

• Dr. Michael Okun, evolutionary biologist, movement disorders specialist, and Director of the Norman Fixel Institute for Neurological Diseases

• Dr. Matthew Farrer, neurogenetics expert and Professor Of Neurology at the University of Florida

'Your Brain On' is hosted by neurologists, scientists, and public health advocates Ayesha and Dean Sherzai.

SUPPORTED BY: the 2026 NEURO World Retreat. A 5-day journey through science, nature, and community, on the California coastline: https://www.neuroworldretreat.com/

'Your Brain On... Parkinson's' • SEASON 6 • EPISODE 4 (SEASON 3 REUPLOAD)

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LINKS

Dr. Rachel Dolhun:

At the Michael J. Fox Foundation: https://www.michaeljfox.org/bio/rachel-dolhun-md-dipablm

'Ask the MD' series: https://www.michaeljfox.org/ask-md

The Michael J. Fox Foundation on YouTube: https://www.youtube.com/@michaeljfoxfoundation/videos

Dr. Michael Okun:

At the University of Florida: https://neurology.ufl.edu/profile/okun-michael/

The book 'Ending Parkinson's Disease': https://endingpd.org/

The Norman Fixel Institute: https://fixel.ufhealth.org/

Dr. Matthew Farrer:

At the University of Florida: https://neurology.ufl.edu/profile/farrer-matthew/

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References:

Bloem, B. R., Okun, M. S., & Klein, C. (2021). Parkinson's disease. The Lancet, 397(10291), 2284-2303.
Morris, H. R., Spillantini, M. G., Sue, C. M., & Williams-Gray, C. H. (2024). The pathogenesis of Parkinson's disease. The Lancet, 403(10423), 293-304.
Dorsey, E., Sherer, T., Okun, M. S., & Bloem, B. R. (2018). The emerging evidence of the Parkinson pandemic. Journal of Parkinson's disease, 8(s1), S3-S8.
Dorsey, E. R., Okun, M. S., & Tanner, C. M. (2021). Bad Air and Parkinson Disease—The Fog May Be Lifting. JAMA neurology, 78(7), 793-795.
Tsalenchuk, M., Gentleman, S. M., & Marzi, S. J. (2023). Linking environmental risk factors with epigenetic mechanisms in Parkinson's disease. npj Parkinson's Disease, 9(1), 123.
Reynoso, A., Torricelli, R., Jacobs, B. M., Shi, J., Aslibekyan, S., Norcliffe‐Kaufmann, L., ... & Heilbron, K. (2024). Gene–Environment Interactions for Parkinson's Disease. Annals of Neurology, 95(4), 677-687.
Golsorkhi, M., Sherzai, A., & Dashtipour, K. The Influence of Lifestyle on Parkinson's Disease Management. In Lifestyle Medicine, Fourth Edition (pp. 919-924). CRC Press.
Sherzai, A. Z., Tagliati, M., Park, K., Pezeshkian, S., & Sherzai, D. (2016). Micronutrients and risk of Parkinson's disease: a systematic review. Gerontology and geriatric medicine, 2, 2333721416644286.

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