A gut bacterium is showing up β or rather disappearing β across all three phases of COVID-19.
Severely ill patients have less of it.
Recovered patients get it back.
Long COVID patients don't.
Its name is Faecalibacterium prausnitzii. And what it does explains a lot. π
F. prausnitzii is one of the most abundant bacteria in a healthy human gut.
It produces butyrate β a molecule that:
β’ Fuels your colon lining
β’ Seals your gut barrier
β’ Suppresses inflammatory signals
β’ Regulates your immune system
When it disappears, all of that fails at once.
Severe COVID-19
A 2025 meta-analysis pooling data across 10 independent studies confirmed:
F. prausnitzii depletion: logFC = -1.24 (95% CI -1.68 to -0.80)
Translation: It was significantly lower in every severe COVID cohort analyzed.
The more depleted. The sicker the patient.
Recovery
Patients who fully recovered from COVID-19 showed normalization of their gut microbiome β including return of F. prausnitzii β within approximately 6 months.
Butyrate-producing bacteria were among the first to come back.
The gut was healing. The bacteria were the signal.
Long COVID
Liu et al. 2022 (Gut journal) tracked 106 Long COVID patients over 6 months.
F. prausnitzii and Bifidobacterium pseudocatenulatum showed the STRONGEST inverse correlation with Long COVID development of any bacteria studied.
Less of them at baseline = more likely to have persistent symptoms.
Why does this matter beyond the gut?
β F. prausnitzii β β butyrate β gut barrier breaks down
β inflammatory signals enter bloodstream
β cross into the brain
β microglial activation
β brain fog, memory problems, fatigue
This is the same gut-brain pathway seen in Parkinson's and Alzheimer's disease.
Long COVID may be hijacking the same route.
A randomized controlled trial just tested this.
463 Long COVID patients. Synbiotic targeting gut bacteria (SIM01) vs placebo. 6 months.
Results (Lancet Infectious Diseases 2024):
Difficulty concentrating: 62% vs 39% alleviated β
Memory loss: 42% vs 27% β
Fatigue: 63% vs 43% β
Pulmonary symptoms: no significant difference.
The gut fixed the brain symptoms. Not the lungs. That tells us something.
What we do NOT yet know:
β’ Whether F. prausnitzii depletion causes Long COVID β or is caused by it β or both
β’ The SIM01 trial used vitamin C as placebo, not inert starch
β’ Results need independent replication
β’ Direct F. prausnitzii supplement does not exist yet
Association is strong. Causation is unproven. That's where the science actually is.
No F. prausnitzii supplement exists yet. But you can feed it.
NOTE: Probiotics carry real risks for immunocompromised individuals and the elderly. Always consult your doctor.
This is part of a disease series on Faecalibacterium prausnitzii β one gut bacterium found depleted across Parkinson's, Alzheimer's, MS, IBD, diabetes, cancer, and now Long COVID.
Parkinsonβs x.com/Neuroscope_mp/β¦
Alzheimerβs x.com/Neuroscope_mp/β¦
Aging x.com/Neuroscope_mp/β¦
Full referenced deep-dive on coming soon
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BREAKING: A new Alzheimer's drug just did something no tau therapy has ever done in a randomized trial β cut tau in the brain by up to 65% AND slowed cognitive decline.
The trial is CELIA, run for 76 weeks.
But there's a twist that has Wall Street nervous. π§΅
Most Alzheimer's drugs (like Leqembi) target amyloid plaques.
This one β diranersen (BIIB080) β targets tau, the OTHER hallmark protein that tangles up inside brain cells and tracks more closely with memory loss.
Instead of cleaning up tau after it builds up, Diranersen turns down production at the source.
It's an βantisense oligonucleotideβ (ASO) β think of it as software that tells the cell βmake less tauβ before the mess even forms.
π¨ BREAKING
A common diabetes pill β already in millions of medicine cabinets β may be the most targeted drug yet tested for the most common genetic form of ALS.
We're talking about Metformin + C9orf72 ALS.
Here's what the science actually says. π§΅π
First β what makes C9orf72 ALS different?
It's caused by a genetic mutation (a "repeat expansion") that produces toxic proteins called DPRs β dipeptide repeat proteins.
These proteins poison motor neurons. There's no approved drug that targets them.
Until now, maybe. π§¬
Here's the mechanism β stay with me, this is important:
C9orf72 mutation β toxic RNA β activates a stress enzyme called PKR β PKR cranks up production of toxic DPR proteins β motor neurons die.
BREAKING:
A 27-million-patient study found new Parkinson's diagnoses spike after COVID-19 infection β peaking around 6 months later.
But the real story isn't what you'd expect. π§΅π
The study: 27,614,510 patients, propensity-matched for age/sex/smoking.
COVID+ patients had significantly higher odds of a new Parkinson's diagnosis at 3, 6, 9 & 12 months post-infection (peak odds ratio ~1.25 at 6 months).
The twist: that elevated risk disappeared after 12β24 months.
That pattern doesn't scream "COVID causes Parkinson's from scratch." It looks more like that was already quietly developing.
This one bacterium keeps disappearing in Long COVID β and it might explain the brain fog and crushing fatigue.
Severe COVID patients lose it.
People who fully recover get it back.
Long COVID patients? It stays gone.
The lower your levels, the worse your symptoms.
The same bacterium is missing in Parkinson's disease.
In Parkinsonβs (especially gut-first type):
F. prausnitzii is consistently depleted.
Lower levels = worse motor symptoms, balance, and walking.
A recent study even showed restoring it in mice improved motor deficits and reduced alpha-synuclein aggregates in the brain.