Neuroactive Compounds As Biomarkers
Sensory hyper- and hypo-responsiveness are typically characteristic of autistic patients even though they are not part of the core definition of ASD. However, diet and probiotic interventions might alleviate them. A variety of neuroactive compounds that activate or inhibit central neurons are produced by gut microbiota, such as serotonin, GABA, dopamine and histamine .
Other studies in animal models have shown that impaired learning and increased depression-like behaviors were observed in a mice model, after the depletion of the gut microbiota by antibiotics. This was correlated with alterations in the levels of 5-hydroxyindoleacetic acid, 5-HT, homovanillic acid, DA, and noradrenaline, and in the mRNA levels of the corticotrophin-releasing hormone receptor 1 and the glucocorticoid receptor . Another type of intervention involves using epigenetic dysregulation as a pharmacological target. Thus, it was shown that sodium butyrate, acting as a histone deacetylase inhibitor, improved social and repetitive behavior in BTBRT +tf/J mice. The administration of sodium butyrate had an effect on the transcriptome of several neurotransmitters and regulatory genes . Overall, these studies reinforce the correlation between ASD symptoms, gut microbiota and levels of neurotransmitters, and suggest that interventions focused on neurotransmitters could have the potential to reduce ASD behavioral symptoms.
The Unbalanced Gut Flora Present In Some People With Autism Is Not A Driver Of The Condition But Rather A Consequence Of Eating Behaviors Characteristic Of The Condition A New Study Claims
Ruth Williams
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The gut microbiome has been suggested to influence a variety of human health conditions, including autism spectrum disorder. This has led to proposals that altering the microbiomewhether by diet, probiotics, or fecal transfermight alleviate symptoms. A study published in Cell today , however, turns this idea on its head. Rather than gut microbes influencing autism spectrum disorder behavior, the paper argues, it is the eating behavior of people with ASD that drives the make-up of their gut microbiomes. While the findings raise doubt about the potential of microbiome-manipulating treatments for ASD, not everyone is ready to throw the bacteria out with the bathwater.
Kevin Mitchell, a developmental neurobiologist and geneticist at Trinity College Dublin who was not involved in the study, says he has long had doubts about the contribution of gut microbes to ASD, so when he read the Cell study, he punched the air because it basically confirms my expectations of what was going on. Namely, that the microbiome has far less influence on ASD symptoms than the extensive literature would have one believe.
Significantly Fewer Gut Bugs Linked To Neurotransmitter Activity
Children with autism seem to have a distinctive and underdeveloped range and volume of gut bacteria that isnt related to their diet, suggests a small study published online in the journal Gut.
They have significantly fewer bacteria linked to neurotransmitter activity and 5 species of bacteria that arent typically found in the guts of children without the condition, suggesting that there may be a characteristic microbial profile for autism, which may pave the way for treatment early on, say the researchers.
Apart from genetic factors, it has been suggested that the gut microbiome may have a part to play in autism spectrum disorders. And the evidence suggests that the pathway between gut bacteria and the central nervous system, referred to as the gut-brain axis, has a profound effect on social behaviours.
Diagnosing autism spectrum disorder can be difficult, because there is no definitive medical test and diagnosis is based on physician assessment.
The researchers therefore wanted to see if 3-6 year olds with autism might harbour a microbiome that differs significantly from that of typically developing children, which might be used to facilitate early treatment.
They compared the range, volume, and associated functions of bacteria in the stool samples of 128 Chinese children, 64 of whom had autism spectrum disorder and 64 of whom didnt.
Clostridium, Dialister and Coprobacillus were enriched in children with autism while Faecalibacterium was significantly decreased.
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How Can Gut Bacteria Impact Mental & Physical Health
Medical research is still uncovering much of the impact the microbiome has on overall health. Your microbiome not only affects your digestion, but it has also been correlated to mood and mental health, cardiovascular health, muscle and joint health, metabolism, immune health, and even your risk of cancer.
Your age, genetics, environment, current diet, and medication history can all impact your gut microbiome. For example, if you needed a long course of antibiotics, you may suffer some digestive issues as a result.
Research Could Help Guide Parents
Andrew Whitehouse the professor of autism research at the Telethon Kids Institute and the research strategy director at Autism CRC said about 2 per cent of Australians are on the autism spectrum.
“What this study shows is that the microbiome in and of itself is in no way a cause of why the brain develops differently and why children develop autism,” Professor Whitehouse said.
“But what it also does urge us to do is to help promote healthy balanced diets in kids so they get all the nutritional intake they can get that can help promote their development.”
He said when a child is diagnosed as being on the autism spectrum, families are often “inundated” with information about different therapies and potential treatments.
“It’s such a challenge for families to understand what is actually a valid pathway to go down and what is straight charlatanism,” he said.
Professor Whitehouse said he had met families who had tried a variety of diets, including gluten and casein-free regimes and diets for different blood types.
“All of these have no evidence to support their use with children on the autism spectrum, but people try them because they are desperate to help support their child,” he said.
“What this study really does is close off one of those false leads that people have been promoting, so parents can help concentrate their time, effort and financial resources on the best means to help support their children.”
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Progress In Understanding The Gut Microbiome
The distal gut microbiome is typically assayed via stool because of the non-invasive route of collection, and have provided important insights into the distal gut microbiome composition and function. However, it is important to recognize that adherent microbiota residing on mucosal surfaces of the gut may be vastly different from those present in fecal material furthermore, different compartments of the gut may be locally colonized by distinct communities of bacteria. The procedures required to sample adherent species are invasive, expensive and impractical for a typical research study. Nevertheless, while existing data on the distal gut microbiome should be interpreted with this limitation in mind, there is much to be learned even from the partial information available from metagenomic analysis of stool.
Discovery Lays The Groundwork For Future Blood Tests To Screen For Autism And Treat The Condition Early Researcher Says
Andrea Gordontimer
Researchers have identified a unique blood marker that shows a link between gut bacteria and autism in some children diagnosed with the neurodevelopmental disorder.
In a new study , they found evidence of abnormal energy metabolism in a group of autistic children as a result compounds produced by gut bacteria frequently found in people with autism.
The discovery lays the groundwork for future blood tests to screen for autism and treat the condition early, says co-author Dr. Derrick MacFabe, director of the Kilee Patchell-Evans Research Group at the University of Western Ontario. He collaborated with researchers from the Arkansas Childrens Hospital Research Institute in Little Rock.
While gastrointestinal problems are common among children with autism, research to understand the connection and develop potential treatment is still in the early stages. To date, much of the effort has been directed at unravelling the genetic markers of the disorder, and toward early identification and behavioural intervention.
However, there is increasing evidence that autism, like many other disorders, is the result of a combination of genetic and environmental factors that affect the body and the brain, says MacFabe, whose research team focuses on the role of the gut and its trillions of important bacteria that are key to health.
It also indicates there was no genetic factor causing the abnormal energy metabolism, and points to an environmental trigger.
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Microbiome Likely Not A Causal Factor For Autism Suggests Largest Study
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Animal Models For The Study Of The Relationship Between Gut Microbiota And Asd
Animal models can potentially play an important role in ASD research . There are many genetic models for the study of autistic disorders . However, there are no animal models that exhibit all the symptoms of human neurodevelopmental impairment. Experiments for the study of ASD have been conducted in zebrafish, monkeys, and songbirds, but mainly in rodents bred in laboratories, such as rats or mice . Rodents are suitable for the study of ASD because their behavior is well studied and there are a number of well-established techniques to manipulate their nervous system. Moreover, rats and mice are social animals and their relationships for parental, sexual or territorial behaviors, among others, are well-established. Initial ASD studies were conducted in rats, as their social behavior is clearly displayed. However, as mice are cheaper, their use for ASD study has been increasing. As a general rule, social behavior is measured by a series of tests such as the Morris water task, the three-chambered social interaction, swimming tests or simply by evaluating the explorative behaviors .
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The Gut Microbiota And Autism Spectrum Disorder : A Major Paradigm Shift
Recent studies in France and the United States, both on mouse models and human patients, have clarified the link between the gut bacteria and autism. Moreover, a recent study led Prof. Krajmalnik-Brown and Prof. Adams of Arizona State University, in partnership with Dr. Sarkis Mazmanian of Caltech, to the idea that restoring a harmonious bacterial ecosystem might alleviate the symptoms of autism.
- As a result, in 2017, they tested a process called microbiota transfer therapy on 18 autistic children with gastrointestinal symptoms between the ages of seven and 16. Of these participants, 15 were considered to have a form of severe autism.
Results of microbiota transfer therapy in autistic children: The results of the study showed a remarkable reduction in autism symptoms. After two years, only three of the 18 children were considered to still be severely autistic, while eight were below the diagnostic threshold for autism, meaning that these eight children are now considered to be neurotypical.
Autism Spectrum Disorder Associated With Gut Microbiota At Immune Metabolomic And Neuroactive Level
- 1Gut Microbes and Health Institute Strategic Program, Quadram Institute Bioscience, Norwich, United Kingdom
- 2Department of Nutrition and Food Science, Complutense University of Madrid, Madrid, Spain
There is increasing evidence suggesting a link between the autism spectrum disorder and the gastrointestinal microbiome. Experimental and clinical studies have shown that patients diagnosed with ASD display alterations of the gut microbiota. These alterations do not only extend to the gut microbiota composition but also to the metabolites they produce, as a result of its connections with diet and the bidirectional interaction with the host. Thus, production of metabolites and neurotransmitters stimulate the immune system and influence the central nervous system by stimulation of the vagal nerve, as an example of the gut-brain axis pathway. In this review we compose an overview of the interconnectivity of the different GI-related elements that have been associated with the development and severity of the ASD in patients and animal models. We review potential biomarkers to be used in future studies to unlock further connections and interventions in the treatment of ASD.
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What Are Gut Bacteria
Although we often think about bacteria as bad because they cause disease, the human body actually needs bacteria in the digestive system to function.
We have about 100 trillion bacteria in our gut, comprising around 1,000 species and 5,000 distinct strains. The bacteria break down the food we eat so we can get as much nutrition as possible out of it. Our gut bacteria are often referred to as the microbiome or flora.
Could Treating Gut Bacteria Help Autism Symptoms
HealthDay Reporter
FRIDAY, April 12, 2019 — Scientists suspect that your gut microbiome — the mix of bacteria that inhabit your intestines — affects your health in many ways, but a surprising new finding suggests that a healthy microbiome may even ease the symptoms of autism.
The small study of 18 children with autism who also had severe digestive problems found that a fecal transplant to rebalance their gut microbiome reduced both their digestive symptoms and their autism symptoms. The improvements persisted during the two-year study follow-up period.
“We treated children with autism by altering the gut microbiota. All had gastrointestinal symptoms — diarrhea, constipation, stomach pain — and those symptoms were reduced dramatically, and their behavior improved as well,” said study senior author Rosa Krajmalnik-Brown. She’s a professor at the Biodesign Institute at Arizona State University in Tempe, Ariz.
“When we checked again two years later, behavior was even better and gastrointestinal symptoms were still much better, but not as good as right after treatment,” she said.
Krajmalnik-Brown said it’s not clear exactly how improving the microbiome helps autism symptoms. Because all of the children had severe digestive issues, she said it’s possible that “they may be more comfortable and better able to focus and learn,” she suggested.
The treatment increased the diversity of microbes and healthy bacteria in the gut, according to the researchers.
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Distinctive Gut Microbiome Unrelated To Diet May Characterise Children With Autism
- Significantly fewer gut bugs linked to neurotransmitter activity
- 5 microbes in guts of kids with autism not found in those without
Children with autism seem to have a distinctive and underdeveloped range and volume of gut bacteria that isnt related to their diet, suggests a small study published online in the journal Gut.
They have significantly fewer bacteria linked to neurotransmitter activity and 5 species of bacteria that arent typically found in the guts of children without the condition, suggesting that there may be a characteristic microbial profile for autism, which may pave the way for treatment early on, say the researchers.
Apart from genetic factors, it has been suggested that the gut microbiome may have a part to play in autism spectrum disorders. And the evidence suggests that the pathway between gut bacteria and the central nervous system, referred to as the gutbrain axis, has a profound effect on social behaviours.
Diagnosing autism spectrum disorder can be difficult, because there is no definitive medical test and diagnosis is based on physician assessment.
The researchers, therefore, wanted to see if 3-6-year-olds with autism might harbour a microbiome that differs significantly from that of typically developing children, which might be used to facilitate early treatment.
They compared the range, volume, and associated functions of bacteria in the stool samples of 128 Chinese children, 64 of whom had autism spectrum disorder and 64 of whom didnt.
Supporting Good Digestive Health
Here are some general recommendations for improving gut health:
- Eat fermented foods. Yogurt, kefir, pickles, sauerkraut, kimchi, miso, and other foods are fermented, and you can often find live cultures versions in your local grocery store. Including fermented foods in your diet keeps your gut healthy by replenishing healthy bacteria and yeasts, and keeping the balance in your stomach and intestines.
- Consume a balanced diet. Eat enough fruits, vegetables, whole grains, and lean proteins to keep your digestive system happy, and to ensure you are getting enough vitamins and minerals to support your overall health. This typically keeps your gut bacteria in check too. In some cases, you may need some additional support for your gut health.
- Try probiotic supplements. If your child is picky about foods and the flavor or texture of fermented foods does not appeal to them, you can try a probiotic supplement instead. Supplements move through the digestive system differently than food, but your child can still benefit from the nutritional support they bring.
While dietary changes, vitamins and supplements, and other methods of supporting gut health can be vital aspects of helping your child on the autism spectrum, these methods should be used in conjunction with behavior therapy. Applied behavior analysis is the leading approach to managing autism symptoms and promoting positive behavioral changes in children and adults who are on the spectrum.
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Future Research Options For Treating Autism Linked To Gut Bacteria
Additionally, the MIT researchers who studied how viral infections can affect autism risk have proposed treating mothers with therapeutics that block the activity of certain strains of gut bacteria. However, this remains a long way off, since their initial findings in mice must first be validated in humans before drug development can become feasible.
Overall, it is clear that there are strong links between autism and gut bacteria. It will be exciting to follow future studies probing autism linked to gut bacteria, especially as researchers seek to develop therapeutics that can make a difference in the lives of patients and parents. Already, cutting-edge research has led Tesseract Medical to develop advanced butyric acid products designed to optimize the ability of these supplements to provide critical support for patients.
Foundational Medicine Review provides reliable, evidence-based information about gastrointestinal health, neurological disorders, and the links between them. Join our mailing list to stay up-to-date on the latest news, research, and analysis.
Works Cited
DeAngelis M, Piccolo M, Vannini L, Siragusa S, De Giacomo A et al. 2013. Fecal microbiota and metabolome of children with autism and pervasive developmental disorder not otherwise specified. PLOS One.