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Gut microbiome–autism link flipped on its head While some scientists have suggested that autism spectrum disorder (ASD) may be at least partly caused by differences in the composition of the gut microbiota, based on the observation that certain types of microbes are more common in people with autism, Australian researchers have said that this link may actually work the other way around.
T
he new study claims that the diversity
by reports that autistic children have high rates of
composition than 16S analysis, a technique used in
gut problems — but that hype has outstripped the
many of the earlier studies linking the microbiome
evidence,” said senior author Dr Jacob Gratten,
to autism.
Head of Mater Research’s Cognitive Health Genomics Group.
“We also carefully accounted for diet in all our analyses, along with age and sex,” said first author
in species found in the guts of children with autism
“Our study, which is the largest to date, was
Chloe Yap, who is completing her medical degree
may be due to their restricted dietary preferences,
designed to overcome some of the limitations of
and PhD at UQ. “The microbiome is strongly
rather than the cause of their symptoms. The
prior work.”
affected by the environment, which is why we
research was funded by the Autism CRC and led by
The investigators analysed stool samples from
designed our study with two comparison groups.”
Mater Research and The University of Queensland
a total of 247 children between the ages of two and
Based on their analysis, the researchers found
(UQ), with findings published in the journal Cell.
17. The samples were collected from 99 children
limited evidence for a direct association of autism
Over the past decade, as next-generation
diagnosed with ASD, 51 paired undiagnosed
with the microbiome. Indeed, Dr Gratten said that
sequencing of the microbial species in the gut has
siblings, and 97 unrelated, undiagnosed children.
out of more than 600 bacterial species identified in
made analysis of the microbiome more automated
The subjects included in the analysis were from the
the gut microbiomes of study participants, only one
and less time-consuming, a number of studies
Australian Autism Biobank and Queensland Twin
was associated with a diagnosis of ASD.
have examined the link between particular species
Adolescent Brain Project.
However, the researchers did find a highly
of microbes in the gut and mental health. The
The investigators analysed the samples by
significant association of autism with diet and that
gut–brain axis has been linked not only to ASD
metagenomic sequencing, which looks at the
an autism diagnosis was associated with less diverse
but also to anxiety, depression and schizophrenia.
entire genome of microbial species rather than
diet and poorer dietary quality; ‘fussy eating’ is
The possibility of targeting the microbiota is thus
short genetic barcodes (as with 16S analysis). It
common among autistic children due to sensory
a growing area of research for new treatments.
also provides gene-level information rather than
sensitivities or restricted and repetitive interests.
“There’s been a lot of hype around the gut
just species-level information, and provides a
Moreover, psychometric measures of degree
microbiome in autism in recent years — driven
more accurate representation of microbiome
of autistic traits (including restricted interests,
32 | LAB+LIFE SCIENTIST - Feb/Mar 2022
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