A Causal Link Between Gut Microbes and Neurological Disease

This post reviews a new study that reveals a large body of evidence confirming a causal link between gut microbes and the onset and progression of neurological diseases like Alzheimer’s, Parkinson’s, ALS, MS and Huntington’s disease via the microbiota gut-brain axis.

Microbes in the human G.I. tract have been linked with many chronic diseases including cancer, rheumatoid arthritis and cardiovascular disease. For example, the bacterial toxin trimethylamine Noxide has been shown to promote the development of cardiovascular disease.

More recently, research has also shown that gut microbes also contribute to the buildup of senile plaques, inflammation and oxidative stress in neurological diseases such as Alzheimer’s, ALS, Parkinson’s, MS and Huntington’s disease.

Changes in gut microbes are known to activate brain inflammation, trigger movement disorders and cause cognitive impairment. 


Metagenomics analyzes all the genetic material gathered from the microbes in a sample. It can be used to study a specific community of microorganisms residing in the G.I. tract of a human.

The authors of the study Correlation between the gut microbiome and neurodegenerative diseases: a review of metagenomics evidence, reviewed articles published in the PubMed/MEDLINE database between the years 2018 and 2023.

To find relevant articles, they conducted keyword searches for “metagenomics,” “microbiota,” or “gut microbiome” with each of the following neurological diseases: dementia, Alzheimer’s disease, Amyotrophic Lateral Sclerosis, Parkinson’s disease, Multiple Sclerosis and Huntington’s disease.

They only considered studies involving bacteria, archaea, bacteriophages, fungi, and viruses. They did not include protists or worms in their searches.

Trillions of microorganisms live in the human body and about 95% of these microorganisms reside in the GI tract and should ideally be health-promoting. The composition of the gut microbiota varies at different stages of life and its diversity is impacted by gender.

The microbes that live in the G.I. tract are deeply involved in the metabolic processes of the human body including digestion, immune function, cleansing and how the body makes and uses energy.

Health-promoting gut microbes produce secondary bile salts, choline, neuromodulators, bacteriocins and short chain fatty acids (SCFA) which modulate the immune system.

Reduced amounts of the Lactobacilli probiotics prevent the intestine from using SCFA, which weakens the intestinal barrier, resulting in leaky gut.

Gut microbes also create a type of secondary immune system in the intestinal tract that helps keep us healthy.

On the other hand, the brain directly regulates what is secreted in the G.I. tract, which greatly impacts the gut microbes.

There is a two way communication system in the microbiota gut-brain axis which involves neurotransmitters, neuromodulators, neuroimmune pathways, autonomic nervous system, and the neuroendocrine system.

Toxins produced by the microbes in the intestines and inflammatory factors caused by the immune response to the microbes activate immune cells in the central nervous system, ultimately leading to the development of neurodegenerative diseases.

Parkinson’s disease (PD)

Parkinson’s disease is thought to be caused by a variety of environmental factors such as inflammatory bowel disease and infections.

Patients with PD experience constipation before they experience movement problems.

Changes in the gut microbiome composition have been observed in both patients with PD and mouse models of PD.

Alzheimer’s (AD)

Mounting evidence suggests that gut microbiome alterations, or dysbiosis, contribute to Aβ deposition (Amyloid B protein deposits) when compared with healthy controls.

Researchers believe that gut dysbiosis, neuroinflammation, impaired clean-up of old and damaged cell parts and defective proteins create a vicious cycle in AD.

First, intestinal dysbiosis disrupts the integrity of the intestinal barrier which causes a leaky gut. Then pathogenic bacteria and intestinal metabolites enter the circulation through the vagus and enteric nerves. Next, neuroinflammation triggers the transportation of neurotoxic misfolded proteins, which leads to neuronal death.

The role of dysbiosis in the digestive tract has been discussed increasingly in the disease process of AD within the scientific community.

Amyotrophic lateral sclerosis  (ALS)

Animal models of ALS have been found to exhibit changes in the gut microbiome compared with healthy mice.

Previous scientific work has shown that microbial-derived metabolites are associated with mitochondrial dysfunction, which triggers neural death.

Neurotransmission is hindered when cells cannot remove damaged proteins.

Multiple Sclerosis (MS)

MS occurs in both children and adults. Recent studies have used metagenomics to explore the relationship between gut ecology affected by dietary habits in MS.

Research shows that both pediatric-onset and adult-onset MS are associated with symptoms of intestinal disturbances.

Gut microbiome data showed that Streptococcus is most abundant in secondary progressive MS.

MS patients have gastrointestinal symptoms years before their MS diagnosis.

Many studies have shown different microbe compositions in people diagnosed with multiple sclerosis versus healthy controls.

Huntington’s Disease (HD)

Studies conducted to determine the association between gut dysbiosis and HD using metagenomics have focused primarily on mouse models.

Researchers believe that that gut microbes play a role in signaling transport along the gut-brain axis by altering plasma metabolite levels.

Bacterial and fungal interactions may be a new direction to explore in the context of the pathogenic mechanisms underlying HD.

Its great that the study is looking at the gut microbiota has a probable cause for neurological diseases, but what they’re doing with this information is not helpful. Simply concluding that diet, taking a probiotic and exercising can be beneficial is nothing new, nor is it helpful. Investing time and financial resources into a study such as this, should provide more benefit to people who suffer with neurological diseases.

If certain microbes activate T cells, then what would happen if those microbes were treated?

If certain microbes are increased in numbers and cause inflammation in patients, will treating them provide symptom relief?

Could some of these microbes be causing neurological disease?

Round worms, flukes, tape worms, Babesia and many other parasites have been discovered in the G.I. tract and central nervous system of patients who suffer with neurological diseases. Why are these microbes not being studied?

Why is it that we are no closer to finding the cause or a cure for neurological diseases?

There are real solutions to recover from parasites today!

To restore health, we must focus on treating the cause of inflammation, which are parasites. First, identify the enemy (parasites), then support the body and treat the parasites while following a holistic approach. When parasitic infections are treated effectively, we can overcome inflammation or disease.

If you’re frustrated with the fact that our standard of care STILL doesn’t offer a real solution for treating MS and other diseases, then click on the link below to watch Pam Bartha’s free masterclass training and discover REAL solutions that have allowed Pam and many others to live free from MS and other diseases.

CLICK Here to watch Pam’s masterclass training

Or take the Health Blocker Quiz to see if you could have parasite infections




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