Gut bacteria could be linked to autism, new research suggests.

Pathogens in the stomach alter the brain's development and may increase an individual's risk of suffering from the spectrum disorder, a study implies.

A three-way relationship between the brain, gut and stress hormone cortisol appears to influence how 'messages' are communicated in the body, which may result in autistic symptoms, the research adds.

Lead author Austin Mudd from the University of Illinois at Urbana-Champaign, said: 'Changes during infancy can have profound effects on brain development, and it is possible that the microbiome - or collection of bacteria, fungi, and viruses inhabiting our gut - plays a role in this process.'

The researchers claim further studies are required before this three-way mechanism can be used to determine autism symptoms.

Gut bacteria could be linked to autism, new research suggests (stock image)

COULD AUTISM BE HELPED BY CHANGING A PATIENT'S DIET? PROBIOTICS AND GOING GLUTEN-FREE MAY HAVE BENEFITS Autism may be helped by changing a patient's diet, research revealed in June. Taking probiotics and adopting a gluten-free lifestyle may improve sufferers' social behaviour and ability to express emotions, a study review found. This is thought to be due to gluten causing a 'leaky gut' - where toxins and even undigested food enter the bloodstream and travel to the brain, which may cause autism symptoms. Probiotics are thought to reverse this by strengthening the gut's lining. Study author Dr Qinrui Li from Peking University, said: 'Efforts to restore the gut microbiota to that of a healthy person has been shown to be really effective. 'Our review looked at taking probiotics, prebiotics, changing the diet - for example, to gluten- and casein-free diets. All had a positive impact on symptoms.' Advertisement

How the study was carried out

The researchers analyzed one-month-old piglets.

Piglets were chosen as their brain and gut development most commonly resembles that of humans.

The researchers examined the piglets' feces to determine if bacteria in their stools influences compounds in their blood and brains.

Key findings

Results reveal that the presence of the bacteria Bacteroides and Clostridium in feces is associated with higher levels of a substance involved in cell signalling, known as myo-inositol.

Bacteroides is also linked to increased amounts of a substance, called creatine, in the brain.

The bacteria Butyricimonas was found to be linked to the amino acid n-acetylaspartate (NAA) in the brain, while Ruminococcus lowered NAA's cognitive concentration.

The presence of such bacteria was further found to influence levels of the hormones cortisol and serotonin, both of which are determined by gut bacteria.

Mr Mudd said: 'Changes in neurometabolites during infancy can have profound effects on brain development, and it is possible that the microbiome - or collection of bacteria, fungi, and viruses inhabiting our gut - plays a role in this process.'

The findings were published in the journal Gut Microbes.