LIGHT THERAPY RESEARCH · PARKINSON'S DISEASE

What the research says about light therapy and Parkinson's disease

Photobiomodulation uses specific light wavelengths to support cellular function. It's a key focus in current Parkinson's research. Here's what the studies are finding.

LIGHT THERAPY RESEARCH · PARKINSON'S

What the research says about light therapy and Parkinson's disease

Summary of published research – Not medical advice.

THE CONDITION

Understanding Parkinson's

Parkinson's is a progressive neurological condition.

 

It's best known for tremor, slowed movement, and rigid muscles. But it also affects balance, sleep, mood, thinking, and digestion.

 

For many people, digestive symptoms like constipation appear years before the first tremor.

 

At the cellular level, Parkinson's disease involves the loss of neurons that produce dopamine. This occurs in a specific part of the brain called the substantia nigra.

Parkinson's is a progressive neurological condition.

 

It's best known for tremor, slowed movement, and rigid muscles. But it also affects balance, sleep, mood, thinking, and digestion.

 

For many people, digestive symptoms like constipation appear years before the first tremor.

But researchers are increasingly convinced the story doesn't start there.

THE BIOLOGY OF PARKINSON'S

Two processes researchers keep coming back to

Mitochondrial dysfunction

Mitochondria are the energy producers inside every cell. In Parkinson's, they don't make enough ATP — the fuel cells run on. Without enough energy, dopamine-producing neurons start to break down.

Pajares et al., 2020

Alpha-synuclein buildup

Alpha-synuclein is a protein that, in Parkinson's, folds wrong and clumps together. These clumps disrupt how neurons work. What's striking: they show up in the gut years before they show up in the brain.

Braak et al., 2003

At the cellular level, Parkinson's disease involves the loss of neurons that produce dopamine.

 

This occurs in a specific part of the brain called the substantia nigra.

But researchers are increasingly convinced the story doesn't start there.

the biology of parkinson's

Two processes researchers keep coming back to

Mitochondrial dysfunction

Mitochondria are the energy producers inside every cell. In Parkinson's, they don't make enough ATP — the fuel cells run on. Without enough energy, dopamine-producing neurons start to break down.

Pajares et al., 2020

Alpha-synuclein buildup

Alpha-synuclein is a protein that, in Parkinson's, folds wrong and clumps together. These clumps disrupt how neurons work. What's striking: they show up in the gut years before they show up in the brain.

Braak et al., 2003

LATEST RESEARCH FOCUS

The gut-brain axis

A growing body of research suggests Parkinson's may begin in the gut and travel to the brain — not the other way around.

α-synuclein shows up in the gut

Alpha-synuclein clumps appear in the enteric nervous system years (sometimes decades) before motor symptoms begin.

The microbiome changes early

A 2026 Nature Medicine study found 25% of the microbiome shifts in Parkinson's — and in people at risk, before symptoms.

Two subtypes, two origins

Research now distinguishes "body-first" Parkinson's — where the disease starts in the gut — from "brain-first."

The implication: if the gut is part of the story, treating only the brain leaves half the picture alone.

Menozzi et al., Nature Medicine, 2026 · Braak et al., 2003 · Horsager et al., 2020

PRIMATE MODEL

Refining the dose for clinical translation

In a monkey model of Parkinson's, researchers tested whether higher doses of near-infrared light delivered to the midbrain produced better outcomes. The finding: higher doses were safe but offered less benefit than lower doses — important groundwork for translating PBM into human clinical trials.

Moro et al., Brain Research, 2016

See the study →

RAT MODEL

Dopamine, serotonin, and motor performance

PBM improved dopamine and norepinephrine levels in Parkinson's-model rats. The treated animals also performed better on motor function tests than untreated controls.

Mohammed et al., 2023

See the study →

HUMAN MICROBIOME STUDY

The microbiome changes before symptoms do

A 2026 study in Nature Medicine found that a quarter of the gut microbiome is altered in Parkinson's — and the same alterations show up in genetically at-risk individuals before any symptoms appear. The pattern held across cohorts in the US, Korea, and Turkey.

Menozzi et al., Nature Medicine, 2026

See the study →

IN VITRO RESEARCH · 1070 NM

Cellular aging markers and brain cells

Researchers at Durham University tested 1070 nm PBM on brain cell lines under oxidative stress. The treated cells showed reversal of several markers of cellular senescence — a process linked to neurodegeneration. A full report is forthcoming.

Zarazua Jimenez & Chazot, Durham University research poster

See the poster →

ON THE HORIZON

ON THE HORIZON

What we're watching in Parkinson's research

What we're watching in Parkinson's research

01

Microbiome-based risk screening

If the gut signals Parkinson's years before symptoms, stool-based screening could eventually help identify people at risk early — when intervention research is most likely to make a difference.

02

Combined brain and abdominal protocols

Researchers are exploring whether treating the brain and gut together produces different outcomes than treating either alone. Early data is promising; larger trials are the next step.

03

Body-first versus brain-first subtypes

Not all Parkinson's starts the same way. Research into the body-first and brain-first subtypes may change which interventions are used for which patients.

ON THE HORIZON

ON THE HORIZON

What we're watching in Parkinson's research

What we're watching in Parkinson's research

01

Microbiome-based risk screening

If the gut signals Parkinson's years before symptoms, stool-based screening could eventually help identify people at risk early — when intervention research is most likely to make a difference.

02

Combined brain and abdominal protocols

Researchers are exploring whether treating the brain and gut together produces different outcomes than treating either alone. Early data is promising; larger trials are the next step.

03

Body-first versus brain-first subtypes

Not all Parkinson's starts the same way. Research into the body-first and brain-first subtypes may change which interventions are used for which patients.

Is PBM Safe + FAQ

Title

What is photobiomodulation?

Photobiomodulation (PBM) uses red and near-infrared light to interact with cells. When red and NIR light hits a cell's mitochondria, it activates an enzyme named cytochrome c oxidase. This helps the cell make more ATP, which is its energy source.

 

PBM is a non-invasive and non-thermal therapy. There’s no heat, no surgery, and no drugs involved. Research has been ongoing for decades, with a focus in the last twenty years on brain health, tissue repair, and inflammation.

Why is the gut involved in Parkinson's research?

Because researchers keep finding Parkinson's there before they find it in the brain.


Alpha-synuclein is the misfolded protein linked to the disease. It has been found in the enteric nervous system, which is the network of neurons in the gut wall, years before motor symptoms show up.  
Gut symptoms like chronic constipation often show up decades before the first tremor.  
A 2026 study in Nature Medicine found that about 25% of the gut microbiome changes in Parkinson's. These changes can also be seen in people at genetic risk. This happens even before they show any symptoms.


The emerging picture is that for many people, Parkinson's may start in the gut and travel up the vagus nerve to the brain. This has shifted how researchers think about when and where to intervene.

Does PBM cure Parkinson's?

No. Nothing currently cures Parkinson's.

 

The research explores if PBM can help with underlying processes in Parkinson's. These include mitochondrial function, inflammation, and neurotransmitter activity. Research also looks at whether this support leads to noticeable changes in how patients feel and function over time.

 

Early studies in animals have shown neuroprotective effects. Human research is still developing. This is an active area of inquiry, not a settled answer.

Is photobiomodulation considered safe in the research?

Over decades of studies, PBM has consistently been marked as low-risk. This holds true when it adheres to established wavelength and dosage parameters. It's non-invasive, non-thermal, and doesn't involve UV or ionizing radiation.

 

The most common side effects in studies are mild. They include occasional headaches, temporary eye fatigue from too much light, or slight skin warmth at higher doses. Serious adverse events are rare in the peer-reviewed literature.

 

Talk to your healthcare provider before starting therapy. This is important, especially if you have any medical conditions. This is especially important for people on photosensitizing medications. It also matters for those with a history of seizures or eye conditions.

References
Braak, H., et al. (2003). Staging of brain pathology related to sporadic Parkinson's disease. Neurobiology of Aging.
Horsager, J., et al. (2020). Brain-first versus body-first Parkinson's disease: a multimodal imaging case-control study. Brain.
Menozzi, E., et al. (2026). Microbiome signature of Parkinson's disease in healthy and genetically at-risk individuals. Nature Medicine.
Mohammed, H. S., et al. (2023). Transcranial photobiomodulation and dopamine in Parkinson's-model rats.
Moro, C., et al. (2016). Effects of a higher dose of near-infrared light in a monkey model of Parkinson's disease. Brain Research.
Pajares, M., et al. (2020). Inflammation in Parkinson's disease: mechanisms and therapeutic implications. Cells.
Zarazua Jimenez, J. E., & Chazot, P. Photobiomodulation 1070 nm in normal ageing and neurodegenerative diseases. Durham University research poster.