autism by targeting the gut
June 19, 2017
change the bacteria in the gut, through diet, pro-and prebiotic supplements,
fecal matter transplants or antibiotics, could treat autism. A review of six
decades of research linking the gut to brain development could pave the way for
cheap and effective treatment.
Experts have called for large-scale studies into altering the make-up of
bacteria in the gut, after a review showed that this might reduce the symptoms
of Autism Spectrum Disorder (ASD). Until now, caregivers have relied on
rehabilitation, educational interventions and drugs to reduce ASD symptoms, but
now researchers suggest that treating this condition could be as simple as
changing their diet.
A review of more than 150 papers on ASD and gut bacteria found that since
the 1960s, scientists have been reporting links between the composition of
bacteria in the gut and autistic behaviour. The review highlights many studies
showing that restoring a healthy balance in gut bacteria can treat ASD
“To date there are no effective therapies to treat this range of brain
developmental disorders,” explains Dr Qinrui Li of Peking University,
China. “The number of people being diagnosed with ASD is on the rise. As
well as being an expensive condition to manage, ASD has a huge emotional and
social cost on families of sufferers.”
The link between the gut and ASD is well-known among sufferers: problems
like diarrhea, constipation and flatulence are commonly reported. The root of
gastro-intestinal problems like these is an imbalance of “good” and
“bad” bacteria in the gut.
A cheap and effective treatment?
Many of the papers reviewed support the idea of a gut-brain axis — a way
in which factors in the gut can affect processes in the brain. So these
gastro-intestinal problems may have a more sinister side. The overgrowth of bad
bacteria in the gut inevitably leads to an overproduction of by-products —
including toxins. These can make the gut lining more permeable. Then toxins,
by-products and even undigested food can get into the bloodstream and travel to
In a child under three years old, whose brain is at the height of
development, the presence of these chemicals can impair neuro-development,
leading to ASD.
What causes infants to develop an imbalance in the gut microbiota?
“ASD is likely to be a result of both genetic and environmental
factors” explains Dr Li. “The environmental factors include the
overuse of antibiotics in babies, maternal obesity and diabetes during
pregnancy, how a baby is delivered and how long it is breastfed. All of these
can affect the balance of bacteria in an infant’s gut, so are risk factors for
However, the researchers found a significant body of evidence that
reverting the gut microbiota to a healthy state can reduce ASD symptoms.
“Efforts to restore the gut microbiota to that of a healthy person has
been shown to be really effective” continues Dr Li. “Our review
looked at taking probiotics, prebiotics, changing the diet — for example, to
gluten- and casein-free diets, and faecal matter transplants. All had a
positive impact on symptoms .”
These include such things as increased sociability, a reduction in
repetitive behaviour, and improved social communication: all hugely beneficial
to the life of an ASD sufferer.
The message of this review is one of positivity. This could well be a
breakthrough in the treatment of this disorder. However, the researchers
believe that the studies are too few and too small, and that new clinical trials
are needed to take this research to the next level.
“We are encouraged by our findings, but there is no doubt that further
work needs to be carried out in this field” says Dr Li. “We need more
well-designed and larger-scale studies to support our theory. For now,
behavioural therapies remain the best way to treat ASD. We would hope that our
review leads to research on the link between the gut microbiota and ASD, and
eventually a cheap and effective treatment.”
Materials provided by Frontiers.
Note: Content may be edited for style and length.
Qinrui Li, Ying
Han, Angel Belle C. Dy, Randi J. Hagerman. The Gut Microbiota and Autism
Spectrum Disorders. Frontiers in Cellular Neuroscience, 2017; 11