In a new focused review of nearly 200 publications covering relationships between the autism spectrum disorder and the brain gut microbiome system synthesizes the growing body of research that suggests that the gut microbiota, the trillions of microorganisms that live within the human digestive system, can play critical roles in modulating brain function, social behaviors and autistic symptoms.
The work of the 200 revisions was published in the scientific journal Nutrients.
Gut brain microbiome and autism: potentially related?
Two of the co-first authors of the work, Michelle Chernikova And Genesis Flores, participated in the program Diversity, Inclusion and Access JumpStart from USC, a structured summer research program for talented undergraduate students intending to pursue a PhD, at the time of literature review and manuscript preparation.
Joining as a co-first author is Emily Kilroy Ph.D. ’18, Postdoc ’22, postdoctoral fellow in the division of occupational sciences and occupational therapy at USC Chan. Jennifer Labus and Emeran Mayer, microbiologists at the University of California, Los Angeles, are co-authors. The senior author is Lisa Aziz-Zadeh, associate professor at the USC Chan Division jointly appointed toUSC Dornsife College of Letters, Arts and Sciences’ Brain and Creativity Institute.
The review summarizes current understanding of the mechanisms by which the gut microbiota, metabolic substances and the brain communicate to influence behaviors, including the different social and restricted or repetitive patterns of communication that characterize autism.
Gastrointestinal symptoms such as abdominal pain, constipation and diarrhea have been reported in 46-84% of autistic people, giving rise to a hypothesis that intestinal dysregulation may be particularly widespread in individuals with autism.
“To date, most studies on autism in humans look at the brain and behavior, or the gut microbiome and behavior.“, Said Aziz-Zadeh regarding the correlation of the brain gut microbiome and autism”Our DoD study is one of the largest autism studies to look at all three factors together: brain, gut, and behavior. The current paper on Nutrients establishes the theory behind this effort, reviewing everything from rodent studies on the subject, to potential neurotransmitter pathways that may be involved and potential brain regions that can be modified by this interaction. “
Scientists have yet to determine the exact microbial composition associated with autism, and the authors recommend several future research directions. These include the need for more standardized sampling, collection and analysis; research studying the prenatal gut microbiome in pregnant mothers; studies comparing the microbiomes of autistic and typically developing populations; and longitudinal monitoring of metabolic states and specific biomarkers through early childhood development.
“We were able to see that within an individual, changes in the microbiome were associated with changes in behavior“, he has declared Catherine Lozupone, Ph.D., Department of Medicine microbiologist, University of Colorado, Anschutz Medical Campus, Aurora, Colorado. “If we are to understand the link between the gut microbiome and autism, we need more collaborative efforts in different regions and centers to obtain truly comprehensive generalizable information on this relationship. “
Researchers compared gut microbiome composition between individuals with autism spectrum disorder and neurotypical controls in Arizona and Colorado using standardized DNA extraction and sequencing methods.
The researchers found that the composition of the gut microbiome differed between individuals in Arizona and those in Colorado, and gastrointestinal symptoms were significantly higher in those with autism than in those without autism in Arizona but not Colorado. Gut microbiome composition was significantly associated with autism during study site location control, but not during gastrointestinal symptom control.
The experts also longitudinally assessed the relationship of the gut microbiome with the behavioral severity of autism, diet, and gastrointestinal symptoms in Colorado individuals. “We reached out to participants to study every three months or so and had them fill out a series of checklists, one being the aberrant behavior checklist which examines associated behaviors such as inappropriate speech and repetitive movements.“, Said Dr. Lozupone.
“A bowel frequency questionnaire asked participants what they were eating last week. We also asked what types of gastrointestinal symptoms the participants were experiencing. We got fecal samples to examine the microbiome. We gathered all of this data to see how it related to each of them“.
In the longitudinal analysis, the researchers found that the difference in levels of lethargy / social withdrawal measured in individuals at different time points was related to the degree of change in gut microbiome composition and that worsening of inappropriate speech between time points was associated. to a decrease in the intestinal microbiome.
“We need more research, but our work shows that the gut microbiome is playing a role in symptom provocation in children diagnosed with autism spectrum disorder.“, Said Dr. Lozupone.
“This further supports the fact that the gut microbiome could be a valuable therapeutic target for children with autism spectrum disorders. I know that some labs have explored things like fecal microbiome transplantation in these babies and they have shown promising results.the”.
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