Autism could be cured by poo transplants, according to new research.
Symptoms almost halved in children given the treatment – known medically as microbiota transfer therapy.’
Scientists believe the key to fighting the neurological condition lies in the gut, rather than the brain.
A professional evaluator found a 45 per cent reduction in language, social interaction and behavioural problems – two years afterwards.
These are the main issues linked to autism spectrum disorder, cases of which have risen more than twofold since the turn of the century.
Co author Professor Rosa Krajmalnik-Brown, a microbiologist at Arizona State University, said: “We are finding a very strong connection between the microbes that live in our intestines and signals that travel to the brain.
“Two years later, the children are doing even better, which is amazing.”
At the start, 83 per cent of participants were rated as having “severe” autism.
By the end, this had dropped to 17 per cent – 39 per cent “mild to moderate” and 44 per cent below the cut-off for even mild ASD.
Recent research suggests our gut bacteria, or ‘microbiome’, affect communication between brain cells and overall neurological health.
Worldwide, interest is growing in the idea abnormal quantities of certain bugs may be responsible for triggering a variety of conditions.
Explained Prof Krajmalnik-Brown: “Many kids with autism have gastrointestinal problems, and some studies, including ours, have found those children also have worse autism-related symptoms.
“In many cases, when you are able to treat those gastrointestinal problems, their behaviour improves.”
Over 700,000 people in UK are autistic, which means 2.8m people have a relative on the spectrum.
In the US about one in every 59 children is diagnosed with autism, up from one in every 150 in 2000.
The apparent rise and its stubborn resistance to treatment has spurred a legion of researchers to enter the field and explore the disability in innovative ways.
These include behavioural, speech and social therapy, psychiatric medications and dietary and nutritional approaches.
But no medications have been approved to treat core symptoms such as social communication difficulties and repetitive behaviours.
One promising avenue involves the collection of microbes that lives in our intestines helping us digest food, train our immune system and prevent overgrowth of harmful bacteria.
The study published in Scientific Reports found most of the initial improvements in gut symptoms remained.
What is more, parents reported a slow steady decline in ASD symptoms both during treatment – and over the next two years.
Up to 50 percent of autistic patients have chronic gastrointestinal (GI) problems, mainly constipation and diarrhoea that can last for many years.
That discomfort and pain can cause irritability, decreased attention and learning, and negatively impact behaviour.
An earlier study with the antiobiotic vancomycin found major temporary improvements in GI and autism symptoms.
But the benefits were lost a few weeks after treatment stopped despite use of over-the-counter probiotics.
Prof Krajmalnik-Brown and colleagues showed by transferring healthy microbiota to individuals lacking certain gut bacteria, it is possible to “donate” a more diverse set of bacteria into the patient and boost health.
The therapy involved pre-treatment with vancomycin, a bowel cleanse, a stomach acid suppressant, and daily poo transplants for seven to eight weeks.
At the beginning the children were found to have lower diversity in their respective gut microbes and were depleted of certain strains of helpful bacteria, such as Bifidobacteria and Prevotella.
Prof Krajmalnik-Brown said: “Kids with autism are lacking important beneficial bacteria, and have fewer options in the bacterial menu of important functions that bacteria provide to the gut than typically developing kids.”
The treatment substantially increased microbial diversity and the presence of helpful bacteria, including Bifidobacteria and Prevotella.
After two years, diversity was even higher and the presence of beneficial microbes remained.
The work is not only about treating patients but also about learning from the treatment in order to develop better formulations and optimise dosing.
Prof Krajmalnik-Brown said: “Understanding which microbes and chemicals produced by the microbes are driving these behavioural changes is at the heart of our work.”
Two years after treatment stopped the participants still had an average 58 per cent reduction in GI symptoms.
In addition, the parents of most of the 18 participants reported “a slow but steady improvement in core ASD symptoms.”
Every family completed the study, and returned two years later for a follow-up evaluation.
The treatment was generally well-tolerated with minimal adverse effects.”
Poo transplants were pioneered more than 30 years ago by Dr Thomas Borody, an Australian gastroenterologist at the Centre for Digestive Diseases, Sydney.
He said: “I would call it the highest improvement in a cohort that anyone has achieved for autism symptoms.”
Co author Dr Greg Caporaso, a leading expert in microbiome data science at Northern Arizona University, says the team are “excited”.
But larger clinical trials involving hundreds of autistic children are required before it can be approved as a treatment by the US Food and Drug Administration.
Autism is an incurable, lifelong developmental condition that affects how people perceive the world and interact with others.