The connection between Autism Spectrum Disorder (ASD) and the body ‘second brain‘ is clearer than ever.
A new paper, authored by no fewer than 43 scientists from different disciplines, has found the strongest link yet between gut microbes, host immunity, genetic expression in the nervous system and dietary habits.
The new analysis does not confirm this autism‘S underlying causesnor does it identify itself specific subtypes like other research has triedbut rather reveal a more general gut profile that appears to be consistent in those with ASD.
If further research can elucidate this crucial biomarker, it could one day be used to diagnose ASD and investigate possible treatments.
“Before we had smoke, suggesting the microbiome is involved in autism, and now we have fire.” says Microbiologist Rob Knight from the University of California San Diego.
“We can apply this approach to many other areas, from depression To Parkinson’s To Cancerwhere we think the microbiome plays a role, but we don’t yet know exactly what role it plays.”
Scientists now know that people with autism are more likely to suffer from gastrointestinal problems such as constipation, diarrhea, bloating and vomiting.
In addition, researchers have started to do this in recent years to find links between the makeup of the microbes that house our gut and neurodevelopmental disorders such as ASD.
However, this association is not always consistent, and some experts have not argued It’s not necessarily gut bacteria that trigger ASD; It could be that children with autism are more likely to restrict their diet because they are “picky” about eating, which in turn affects the types of bacteria that remain in the digestive tract.
The new study includes 10 existing datasets on autism and the microbiome, as well as 15 additional datasets on human brain nutritional patterns, metabolism, immune cell profiles and gene expression profiles.
The authors of the analysis say Their results increase “the statistical power and biological insight” into the gut-brain axis behind ASD and provide “stronger associations between gut microbes, host immunity, brain expression, and dietary patterns than previously reported.”
The basic connection between the gut and the brain is itself a relatively new area of science. In 1992 a researcher called the gut is “the neglected human organ” and it was not until the 21st century that the term “human microbiome” was properly conceptualized.
Since then, research into the trillions of individual microbes that live in our gut has taken off, and yet experts are still not quite sure what to make of their findings. It is not yet clear what a healthy microbiome looks like, let alone an atypical one.
There are just so many variables to consider, especially because the communication between gut and brain seems to be two-way and diet can be change so quickly the mixture of intestinal bacteria.
In 1998, a scientist named ER Bolt came along for the first time supposed An abnormal gut microbiota could be involved in the development of ASD.
For example, people with autism showed more A kind of Clostridium And ruminococci bacteria in their stool than that of a control group.
But these early studies were general as viewed According to a trio of Dutch nutrition researchers who reviewed the evidence in 2014, the quality was “of low to moderate quality, mainly due to small sample sizes”, “insufficient or no explanation of the sources” of the stool samples and “potential bias”.
Even today, carefully designed long-term studies are difficult to obtain and there is little consistency from paper to paper.
The current analysis attempts to fill this gap by comparing existing data on the gut and the ASD. For each dataset, the research team developed an algorithm to match the best pairs of autistic and neurotypical individuals by age and sex, two common confounders in autism studies.
Rather than analyzing study averages, these 600 pairs were each considered as a single data point, allowing the researchers to simultaneously analyze gut microbial differences in more than a thousand individuals.
Ultimately, the authors found key signs of autism in certain metabolic pathways related to diet, gene expression, and certain gut microbes.
Furthermore, these microbes matched those identified by a current long-term study on stool transplants in 18 children with ASD. At a two-year follow-up, participants demonstrated sustained improvements in gastrointestinal and behavioral symptoms based on the scale most commonly used to rate symptoms of ASD.
Overall, the results suggest a potential role for the microbiome in improving autism symptoms, although it’s not yet clear how these underlying gut changes might be related to actual brain changes.
“We were able to harmonize seemingly disparate data from different studies and find a common language to unify them.” explained Jamie Morton, who worked on the paper as a biostatistician at the Simons Foundation, a nonprofit organization that funds biomedical research.
“In many studies, we were able to identify a microbial signature that distinguishes autistic from neurotypical individuals. But the bigger point is that going forward, we need robust long-term studies that examine as many datasets as possible and understand how they change, if there is one [therapeutic] Intervention.”
The study was published in natural neuroscience.
