The brain’s hidden cleaning system: How night-time detox could hold clues to Alzheimer’s, Parkinson’s & ALS/MND

research2693
Nov 4
6 min read

The river that runs through your brain

Every night, while you drift into sleep, a quiet river runs through your brain. You don’t feel it or hear it, but this invisible flow may be one of the most important systems keeping your mind clear and your memories alive.

Only a little over a decade ago, scientists discovered this hidden network — the glymphatic system — a series of microscopic channels that act as the brain’s cleaning crew. Like night-shift workers in a great city, they sweep through while you sleep, flushing away waste and keeping the machinery of thought running smoothly (Nedergaard & Louveau, 2023).

How the brain washes itself

The brain floats in a clear liquid called cerebrospinal fluid (CSF), which cushions and protects it. During deep sleep, CSF moves through channels surrounding blood vessels, rinsing away discarded proteins such as amyloid-beta, tau, and alpha-synuclein — the same debris linked with Alzheimer’s, Parkinson’s, and other neurodegenerative diseases (Zhao et al., 2024).

This cleaning relies on three key forces. Healthy blood flow acts as the pump, gently pulsing the fluid forward. Tiny protein doorways known as aquaporin-4 (AQP4) channels control how easily CSF seeps through brain tissue — like miniature taps along the pipes. And most important of all, deep, restorative sleep opens the floodgates, letting the rinse cycle run at full strength (Nedergaard & Louveau, 2023).

When these parts fall out of rhythm, waste lingers. The city slows. The brain tires.

When the flow falters

As we grow older, or when high blood pressure, diabetes, chronic inflammation, or poor sleep take hold, this flow can stiffen and stall (Hong et al., 2025). The arteries lose their pulse; those AQP4 taps drift from their normal position; the gentle tide that once cleansed the brain becomes a sluggish stream.

Recent studies even show that misplaced AQP4 channels — tiny taps out of alignment — are linked with slower thinking and memory decline in older adults (Wang et al., 2025). The pattern is clear: when the plumbing backs up, the mind’s clarity can fade.

Yet science reminds us to stay humble. The glymphatic system is not the whole story of brain ageing — it is one river feeding into a far larger ocean of blood flow, immunity, and energy. Still, by understanding this river, we glimpse one of the brain’s most elegant repair tools.

The Cambridge discovery that changed the map

In 2025, researchers at the University of Cambridge analysed MRI brain scans from more than 44,000 people in the UK Biobank. They found that people whose CSF moved more slowly were significantly more likely to develop dementia within five years (Hong et al., 2025).

Those same individuals tended to have high blood pressure, diabetes, smoking history, or stiff arteries — conditions that also weaken heart and vascular health. The message was strikingly simple: the heart’s pulse drives the brain’s cleansing tide. Protect one, and you protect the other (Medscape Medical News, 2025).

As lead researcher Professor Hugh S. Markus, MD, from the Department of Clinical Neurosciences at Cambridge, told Medscape Medical News:

“The study shows, with very convincing data, that these markers predict dementia risk, and also that the markers relate to cardiovascular risk factors. This offers a novel way in which one might be able to target or treat dementia. If one could improve glymphatic flow, one could then reduce the risk of dementia.” (Medscape Medical News, 2025)

The finding ties two vital systems — the heart and the brain — into one rhythm and opens a new avenue of hope: that one day, improving the brain’s fluid flow might slow or even prevent cognitive decline.

Alzheimer’s disease — when the rinse cycle slows

In Alzheimer’s disease, waste proteins such as amyloid-beta and tau accumulate faster than the brain can remove them. When glymphatic flow falters, these sticky fragments collect around neurons, jamming communication (Zhao et al., 2024).

Animal experiments show that blocking CSF circulation triggers rapid amyloid build-up, while human imaging links weaker fluid movement to poorer memory. The Cambridge study adds a twist: cardiovascular and metabolic risks — high blood pressure, diabetes — appear to worsen this slowdown (Hong et al., 2025).

It doesn’t prove that fixing glymphatic flow can reverse Alzheimer’s, but it reframes the puzzle: brain health may depend less on isolated brain chemistry and more on whole-body circulation, metabolism, and rest.

Parkinson’s disease — the spreading storm

Parkinson’s disease centres on a different protein, alpha-synuclein, which misfolds and clumps inside nerve cells controlling movement. If the brain’s cleaning system weakens, these clumps may spread like slow-moving ink in water (Xu et al., 2025).

A 2025 meta-analysis confirmed that sluggish glymphatic flow appears across many Parkinsonian disorders (Ghaderi et al., 2025). Poor sleep — a hallmark of Parkinson’s years before diagnosis — may be both cause and consequence: the cleaner can’t work without the night shift, and the night shift fails when the cleaner stalls.

ALS / MND — the fading signal

ALS/MND, gradually damages the nerve cells that control movement. New imaging studies reveal that people with ALS/MND have slower CSF movement and weaker coordination between blood and brain fluid than healthy volunteers (Ni et al., 2025).

This reduced flow may allow inflammation and toxins to build around the spinal cord. Scientists are now combining several brain-scanning tools to track these patterns over time — a step closer to understanding how the body’s fluid rhythms influence nerve survival (Liu et al., 2025).

What we know — and what we don’t (yet)

So far, research shows that the glymphatic system matters — but it isn’t magic. The MRI markers used in studies measure patterns, not the actual fluid in motion, and human trials testing glymphatic “boosters” are still in early stages (Hong et al., 2025).

In animals, certain approaches — gentle light therapy and growth-factor molecules like VEGF-C — have improved waste drainage (Kollarik et al., 2025). But these are experiments, not treatments. What’s real and reliable today is simpler: when circulation, metabolism, and sleep improve, the brain’s rinse cycle tends to follow.

Perhaps the most hopeful discovery isn’t technological at all — it’s biological humility. The brain isn’t sealed off or doomed by fate; it’s part of the living rhythm of the body, cleansing itself night after night, so long as we keep the current flowing.

How You Nutrition Clinic may be able to help

At You Nutrition Clinic we translate this emerging science into compassionate, evidence-informed guidance. We don’t diagnose, but we help people understand how everyday factors — nourishment, metabolism, sleep, and circulation — shape long-term wellbeing.

Through one-to-one nutritional therapy consultations, we explore your personal health story, identify possible imbalances, and design realistic strategies to support comfort, clarity, and resilience. For those living with or caring for someone affected by a neurological condition, we offer understanding and education grounded in current research.

💬 Stay Connected

If you’d like to explore metabolic, immune, or nutritional strategies anchored in science, you can contact You Nutrition Clinic to speak with one of our practitioners about long-term brain and nervous-system health.

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Stay curious. Stay hopeful. Support your brain. 🧠

References

Ghaderi, A., et al. (2025). Meta-analysis of glymphatic impairment across Parkinsonian disorders. Movement Disorders.

Hong, H. S., et al. (2025). Cerebrospinal fluid dynamics and dementia risk: UK Biobank cohort. Alzheimer’s & Dementia. https://doi.org/10.1002/alz.70699

Kollarik, T., et al. (2025). Photobiomodulation and VEGF-C enhance meningeal lymphatic drainage in models of cognitive decline. Brain Research.

Liu, X., et al. (2025). Combined MRI markers reveal glymphatic dysfunction in early ALS. Frontiers in Neuroscience.

Medscape Medical News. (2025, October 24). Brain’s waste clearance system implicated in dementia. WebMD LLC.

Ni, H., et al. (2025). Glymphatic dysfunction in early-stage ALS. Journal of Neurological Sciences. https://doi.org/10.1016/j.jns.2025.00010-3

Nedergaard, M., & Louveau, A. (2023). The glymphatic–lymphatic continuum in neurodegenerative disease. Nature Reviews Neurology, 19(7), 401–417. https://doi.org/10.1038/s41582-023-00886-9

Wang, L., et al. (2025). Aquaporin-4 mislocalisation and cognitive performance in ageing brains. NeuroImage.

Xu, T., et al. (2025). Targeting the glymphatic system to promote α-synuclein clearance. Neuro-Rehabilitation & Neural Repair. Advance online publication. https://doi.org/10.1177/1545968325110000

Yang, W., et al. (2024). Glymphatic dysfunction is associated with cognitive decline in Parkinson’s disease. Brain Communications, 7(1), fcaf029. https://doi.org/10.1093/braincomms/fcaf029

Zhao, Y., et al. (2024). Glymphatic clearance and Alzheimer’s disease risk: A cerebrospinal fluid biomarker study. Alzheimer’s Research & Therapy, 16(112). https://doi.org/10.1186/s13195-024-01612-7