Gut bacteria 'connected to autism'

Microbes in the human gut are connected to autism, a new study has shown.

Re-analysing existing studies, researchers were able to identify a microbial signature that marks out autistic people from neurotypical individuals.

The researchers say that the research highlights the need for further long-term studies to understand the underlying causes of autism.

Previous studies have shown that the microbiome, the collection of microbes that inhabit the human gut, has been shown to play a role in autism, but the mechanics of this link have remained confusing.

Taking a new approach to the problem, a study published today in Nature Neuroscience sheds new light on the relationship between the microbiome and autism.

This research by the Simons Foundation’s Autism Research Initiative (SFARI) and involved reanalysis of dozens of previously published datasets.

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The results align with a recent, long-term study of autistic individuals that centred on a microbiome-focused treatment intervention.

Jamie Morton, one of the study’s corresponding authors, who began this work while a postdoctoral researcher at the Simons Foundation said: “We were able to harmonise seemingly disparate data from different studies and find a common language with which to unite them.

“With this, we were able to identify a microbial signature that distinguishes autistic from neurotypical individuals across many studies.

“But the bigger point is that going forward, we need robust long-term studies that look at as many datasets as possible and understand how they change when there is a [therapeutic] intervention.”

With 43 authors, this study brought together leaders in computational biology, engineering, medicine, autism and the microbiome.

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Co-author Rob Knight, the director of the Center for Microbiome Innovation at the University of California San Diego, said: “The sheer number of fields and areas of expertise in this large-scale collaboration is noteworthy and necessary to get a new and consistent picture of autism.

“We wanted to address the constantly evolving question of how the microbiome is associated with autism, and thought, ‘let’s go back to existing datasets and see how much information we may be able to get out of them.'”

In the new study, the research team developed an algorithm to reanalyse 25 previously published datasets containing microbiome and other “omic” information — such as gene expression, immune system response and diet — from both autistic and neurotypical cohorts.

Within each dataset, the algorithm found the best matched pairs of autistic and neurotypical individuals in terms of age and sex, two factors that can typically confound autism studies.

To the researchers’ surprise, their analysis identified autism-specific metabolic pathways associated with particular human gut microbes.

Importantly, these pathways were also seen elsewhere in autistic individuals, from their brain-associated gene expression profiles to their diets.

Importantly, researchers say these findings go beyond autism.

The approach set forth here could also be employed across other areas of biomedicine that have long proved challenging.

“Before this, we had smoke indicating the microbiome was involved in autism, and now we have fire. We can apply this approach to many other areas, from depression to Parkinson’s to cancer, where we think the microbiome plays a role, but where we don’t yet know exactly what the role is,” says Knight.

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