Health Conditions
Study Identifies 31 ‘Biological Signatures’ in Kids With Autism
Researchers in Hong Kong identified 31 combinations — called “biological signatures” by The New York Times — of bacteria, archaea, fungi, viruses, microbial genes and metabolic pathways that appeared to be biomarkers of autism.
The types of life forms in a child’s gut microbiome may be linked to autism, according to a new peer-reviewed study.
Researchers in Hong Kong analyzed fecal samples from more than 1,600 children ages 1 to 13 with and without autism spectrum disorder (ASD) to identify differences in the types and quantities of gut microbes in kids with ASD, compared with those in children without ASD.
They identified 14 archaea, which are similar to bacteria, 51 bacteria, seven fungi, 18 viruses, 27 microbial genes and 12 metabolic pathways that were altered in kids with autism.
From those, the researchers further identified 31 combinations — called “biological signatures” by The New York Times — of bacteria, archaea, fungi, viruses, microbial genes and metabolic pathways that appeared to be biomarkers of autism.
“The prevalence and relative abundance of these 31 markers differed significantly between children considered neurotypical and children with ASD,” the researchers said in their article published July 8 in Nature Microbiology.
Qi Su, Ph.D., a researcher at the Chinese University of Hong Kong and a lead author of the study, told The Defender that simple tests — like analyzing stool samples for the 31 markers — could help doctors diagnose autism.
Su and his co-authors used machine learning to show that testing for the presence of the 31 markers could accurately indicate whether or not the child had ASD.
The researchers found that testing for all 31 markers was more effective at diagnosing ASD than testing for just one type of microbe — and the testing results were highly accurate regardless of the child’s sex or age, they said in their report.
The findings also could be used to develop treatments for ASD, Su said, as the study “sheds light on how the gut microbiome — made up of bacteria, fungi and viruses — might influence ASD.”
“Understanding which microbes are imbalanced in children with ASD could pave the way for personalized treatments,” Su explained. “For instance, diets, probiotics (beneficial bacteria), or other therapies could be tailored to restore a healthy gut microbiome and possibly improve symptoms.”
Kids with autism had less diversity of gut microbes
For the study, the Hong Kong researchers first identified factors — such as diet, medication and co-morbidity — that might impact a child’s gut health.
“As gut microbiota composition is largely shaped by environmental and host factors,” they said, “we analysed the impact of 236 host factors on the gut microbiome composition to determine potential confounders.”
Of the 236 factors, they identified 21 that showed a significant impact on gut microbiota composition. While taking these pertinent factors into account, they analyzed the children’s stool samples to identify changes in gut microbiota diversity between children considered neurotypical and children with ASD.
Overall, kids with autism had less diversity of archaea, bacteria and viruses compared to kids without ASD.
Bacterial communities in the gut were particularly smaller in kids with ASD, they added.
The researchers acknowledged their study had limitations. It didn’t look at gene factors that may be linked to an ASD diagnosis.
Although they included some confounding factors in their analyses, they said it’s possible that others went unmeasured and could have skewed their results.
They also encouraged more studies on the 31 markers to ensure the markers can be used to accurately diagnose ASD.
That would be a necessary step before manufacturers develop an ASD diagnostic tool that assesses the biological makeup of a kid’s stool.
So far, the U.S. Food and Drug Administration has approved two autism diagnostic tests based on eye-tracking software, according to the Times.
Brian Hooker, Ph.D., Children’s Health Defense chief scientific officer, told The Defender he would have preferred for the researchers to have tested an autism “predictive” tool that could be used with very young children and infants to promote interventions and practices aimed at preventing autistic regression, as over 80% of children with autism experience regression.
The study also would have been stronger if the researchers had looked at how the children’s gut microbiome changed over time, he added.
A more useful study, Hooker said, would be one where gut microbiota were tracked over regression to: first, understand any changes in the microbial composition and second, find any correlates between the “pre-regression” microbiome and later autism diagnoses.
It’s not just about gut bacteria
Dr. James Neuenschwander, the president of a professional group called the Medical Academy of Pediatric & Special Needs that cares for children with ASD and related chronic complex conditions, told The Defender the study is important because it analyzed microbes from multiple kingdoms.
Prior research — including a study by Dr. Andy Wakefield — has shown that gut bacteria in kids with autism differs from the gut bacteria in kids without ASD.
“This is sort of confirmation that it’s not just the bacteria that are different,” according to
Neuenschwander, who said he commonly assesses bacteria levels in his ASD patients and tailors treatments based on the results.
Neuenschwander pointed out that the kinds of biota included in the study — such as fungi, bacteria and viruses — are very distinct from one another because they belong to different kingdoms.
“It’s not like the difference between a mammal and a fish. It’s like the difference between a mammal and a yeast,” he said.
William Parker, Ph.D. — who has researched autism for more than a decade — similarly praised the study for providing “a more detailed analysis” than prior studies.
“There’s been more than 40 studies now showing differences between what we call the biota — all the life that’s in the gut — of people if you compare people with autism to people without autism,” Parker told The Defender. “This study adds to that.”
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Exploring the brain-gut link
Su and his co-authors said their data weren’t enough to suggest a causal link between ASD and the prevalence and abundance of different gut microbes.
“Establishing causality is challenging, but some animal studies have confirmed altering gut microbiota can influence behavior and induce ASD-like symptoms in mice,“ Su said.
He and co-authors suspected that microbiota changes exacerbate autism symptoms.
Both Su and Neuenschwander pointed out that therapeutic interventions aimed at changing the gut microbiota, such as probiotics, have produced beneficial outcomes for kids with autism.
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