Gut Microbiome’s Role in Autism Explored

Your gut is a thriving cityscape of trillions of bacteria, fungi, & other microorganisms that reside together cooperatively or live concurrently within a leviathan of unregulated ecosystems called your gut microbiome. The gut microbiome was always thought to play a role in digestion, and the fact that we now know not only that it plays a role in digestion, like it did in one capacity, but also the role that it plays in regulating mechanisms of mental health should be considered a breakthrough. 

Historically, mental health issues related to anxiety, depression, and, more recently, mood disorders were thought to be explored through the context of the brain and its chemistry. Discoveries related to the gut and its microbial inhabitants tell us that the gut tells the brain in extraordinary ways—by sending signals, releasing neuroactive compounds for mind health regulation, and building resilience with our mood. 

This article will examine the relationship between the gut microbiome and mental health, including which microorganisms and chemical messengers may be involved. It will also discuss promising interventions that support mental health by repairing the gut.

Autism Spectrum Disorder (ASD): A Brief Overview

Autism Spectrum Disorder (ASD) is defined as one type of neurodevelopmental disorder, having difficulties with social interaction, communication, and exhibiting repetitive behavior. It is referred to as “spectrum” because symptom manifestations and severity greatly differ from one individual to another.

Prevalence and diagnosis

CDC reports recent prevalence data while stating around one in 36 children in the United States is diagnosed with an ASD, thereby raising legitimate health considerations for a big section of the population. 

Etiology

A variety of factors contribute to the etiology of autism, involving a sketchy interaction between genetic, environmental, and biological factors.

Common symptoms

These consist of late speech development, poor eye contact, trouble in understanding social cues, and repetitive movements or actions. 

With further research, the spotlight has shifted to biological systems other than the brain, such as the gut microbiome.

Similarities Between Gut Microbiome and Autism

The notion that gut health impacts mental health is not a fad; there is an increasing scientific basis. Research demonstrates that the balance of the gut microbiome may influence emotional stability, stress response, or mental health disorders. 

We will outline the specific microbial changes, gut-derived chemicals, and immune systems that connect our minds and our intestines.

Altered Microbial Profiles in Autism

Autism research suggests particular microbial arrangements common to many individuals with ASD:

• A decreased abundance of species of Bifidobacterium and Lactobacillus, generally thought to be beneficial microbes. 
• Higher levels of Clostridia species that are sometimes considered to be related to inflammation in the gut tumor. 
• Altered ratios between the two bacterial phyla, Firmicutes and Bacteroidetes, which affect metabolism and immunity. 

These divergences stand in correlation with gastrointestinal symptoms often times reported in autism, which include constipation, diarrhea, and abdominal pain.

The Impact of Microbial Metabolites

Some of the gut bacteria metabolites, including propionic acid, a short-chain fatty acid, are considered in relation to causing autism-like behaviours in animal models. Higher-than-normal levels of propionic acid neuroinflammation and alteration of neurotransmitter systems produce symptoms similar to those of ASD. 

Immune Dysregulation and Neuroinflammation

Autism has been linked with immune system abnormalities and neuroinflammation. Gut microbial dysbiosis may also contribute to the development of such conditions by increasing intestinal permeability (leaky gut), allowing microbial products to enter the bloodstream and produce systemic inflammation with repercussions to the brain.

How the Gut Microbiome Influences Autism Symptoms?

Clarifying how the gut microbiome influences autism symptoms will be necessary to create effective interventions at the gut-microbiome interface. Here are some potential mechanisms of action: 

Immune System Modulation and Neuroinflammation

The gut microbiome regulates immune function. Dysbiosis does activate systemic inflammation and activation of neuroinflammation and the role of inflammation in the pathophysiology of autism is increasingly acknowledged.

Intestinal Barrier Integrity and “Leaky Gut” Hypothesis

Some evidence indicates that individuals with autism present with greater disorders of gut intolerance and increased intestinal permeability consistent with the proposal of “leaky gut”. It is thought that a breakdown in gut permeability can allow toxins and metabolites produced by gut bacteria to penetrate the gut barrier and interact via bloodstream with the brain and worsen behavioral symptoms. 

Neurotransmitter Production and Regulation

Gut bacteria regulate the production of many neurotransmitters (e.g., serotonin, GABA) that influence mood and social function. There are well established, known imbalances of these neurotransmitter systems in ASD. 

How Can the Gut Microbiome Influence Autism?

There are many interactive ways the gut microbiome mediates autism:

1. Microbial Metabolites and Neurotransmitter Production

The gut microbiome synthesizes and regulates metabolites, such as short-chain fatty acids (SCFA), that modulate inflammation processes and neurotransmitter systems important for normal brain and behavioural functions. For example:

• Propionate

High levels are associated with behaviors resembling ASD in animal models.

• Butyrate

Supports the gut barrier and exerts anti-inflammatory effects in the body.

• Serotonin

Around 90% of serotonin is produced in the gut and it plays a role in mood and thinking.

Potentially abnormal levels of these metabolites could interfere with normal brain development and/or functions.

1. Immune Dysregulation and Neuroinflammation

Alterations to the gut microbiome could lead to a pro-inflammatory state in the body; it could also increase intestinal permeability (also referred to as “leaky gut”), leading to an internal environment where the bacteria and bacteria-derived components such as lipopolysaccharides (LPS) can cross into the bloodstream. Activation of systemic immune states can also enter the brain, resulting in neuroinflammation – this is present in some cases of ASD (autism spectrum disorder).

1. Gut Barrier Integrity

Healthy microbiota support gut integrity. Dysbiosis increases intestinal permeability and if the gut is permeable and is serving as a barrier, the body may be exposed to toxins, pathogens or even gut metabolites that can have an effect on brain inflammation – leading to brain function and/or behaviors. 

Gastrointestinal Symptoms Commonly Associated with Autism

Individuals with ASD will report gastrointestinal disturbances that may include:

• Chronic constipation or diarrhea: Both chronic conditions result from microbial imbalance that plays an important role in motility.
• Abdominal pain and bloating: Resulting from gas production and inflammation.
• Food sensitivities and allergies: Resulting from altered immune functioning. 

Any or all of the above can exacerbate behavioral problems, including irritability and anxiety, creating an ongoing feedback loop between the gut & the brain.

Therapeutic Strategies Targeting Gut Health in ASD

Therapeutic approaches to restore a healthy gut microbiome are developing for individuals with ASD:

Dietary Interventions

• Gluten-free, casein-free diets: Some believe they reduce gut inflammation and behavioral symptoms in some children; evidence of this intervention remains inconclusive.
• High-fiber diets: promote the growth of beneficial bacteria and SCFA production.

Probiotics and Prebiotics

Some probiotic strains behaved similarly to behavioral medications (improved GI symptoms and some measure of behavior) in clinical trials, with less consistency in percentile improvement. Prebiotics were defined as non-digestible fibers known to feed only good bacteria, helping restore gut balance.

Fecal Microbiota Transplantation (FMT)

FMT includes transferring healthy donor stool to the child with ASD at one point to help restore microbial diversity to the microbiome. Early evidence reported some improvement in gut and sometimes behavioral disturbances. More research with bigger sample numbers is required for evidence linking GI disorders to ASD.

Antibiotic Treatment

Antibiotics have been used cautiously to reduce pathogenic bacteria in the gut, with the caveat that their use could further disrupt the microbiome balance. 

Limitations and Challenges in Microbiome-Autism Research

Even with hopeful research findings, there are challenges: 

• Variability can limit study generalizability and can exist with methods and populations across studies, leading to mixed findings.
• Causal questions remain – are changes to the gut causing mental illnesses/mood issues, or do changes in mental health lead to changes in the gut? 
• The long-term safety of therapies that modify the gut microbiome is still being scrutinized.
• Because microbiomes are very individualized, treatment may naturally need to vary from person to person.

FAQs

1. Can changing my child’s gut microbiome improve autism symptoms?

Yes! There are many different responses and accounts of fantastic changes to emotional state after diet changes, probiotics, and decreasing gut inflammation. 

2. Are there any risks associated with fecal microbiota transplantation (FMT) for autism?

Eating more fiber fruits and vegetables, fermented foods (yogurt, kimchi), omega 3s, and whole grains is beneficial for gut health and mental health support. 

3. How can I test my or my child’s gut microbiome?

There is a growing literature that certain probiotics varying strains of  Lactobacillus rhamnosus, and Bifidobacterium longum may produce some effects, but probiotics are not equal, and the effects of probiotics may be different for all individuals.

4. Do all children with autism have gut microbiome imbalances?

Yes – chronic stress can alter the microbial balance, decrease diversity of the biota, and increase gut permeability. 

5. How long does it take to see improvements from microbiome-based therapies?

Some people experience benefits in as little as 2-4 weeks, while others take several months of continual lifestyle and dietary change to see them.

Conclusion

The gut microbiome-mental health connection is one of the most exciting frontiers in modern medicine. Although it is still in its infancy, the evidence suggests that mental health may not just be improved with therapy and/or medications and other means; we may be able to nurture our mental health by nurturing our inner microbial world. 

If you want to know how much your gut health may be affecting your mood and mental performance, Healify has an individualized gut health model. We offer everything from advanced microbiome tests to bespoke probiotic formulations to help you learn how to maintain a gut-friendly routine that benefits your body and brain. 

Start with a Free Consultation ($0) or our Comprehensive Package for $79… whatever works for your preferences! 

Learn more and start your journey toward better mental health with Healify at HealifyNow.com! 

Evelyn Brown