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Autism and gut bacteria – the surprising link between the mind and the stomach

A recent paper has found that autistic-related social patterns can be reversed when one species of gut bacteria is present in the microbiome of mice. 

Autism – a developmental disorder that causes impediments to social interactions and behaviour – is usually linked by scientists to abnormalities in brain structure and function, caused by a mix of genetic and environmental factors. Scientists have almost always attempted to understand the way autistic people process the world around them by looking to the mind.

According to the National Autistic Society, “There is strong evidence to suggest that autism can be caused by a variety of physical factors, all of which affect brain development; it is not due to emotional deprivation or the way a person has been brought up.”

Recently, however, a lesser-known link to autism has gained traction. This time, the link is not found in the brain but in the gut.

Reporting their findings in the journal Cell, researchers from the Baylor College of Medicine, Texas, found that the presence of a single species of gut bacteria in mice could reverse many behavioural characteristics related to autism.

In the digestive tracts of humans and other animals, there exists a complex, symbiotically integrated network of trillions of microorganisms known as the “gut flora” or “microflora”. The idea that all these bacteria and microorganisms have taken up a home in our gut may initially seem startling, but they serve a number of beneficial purposes, such as aiding digestion and offering immunity from infection.

The potential link between gut flora and autism arose as researchers identified the increased risk of neurodevelopmental disorders, such as autism, among children born from mothers who were obese during pregnancy. The microflora of obese people is demonstrably different from those who are not obese, and as a result, connections have been made to the gut issues often reported in autistic people.

The senior author of the study and neuroscientist Mauro Costa-Mattioli said: “Other research groups are trying to use drugs or electrical brain stimulation as a way to reverse some of the behavioural symptoms associated with neurodevelopmental disorders – but here we have, perhaps, a new approach.”

To determine what the differences in gut bacteria were, the researchers fed 60 female mice a high-fat diet, with the aim of replicating the type of gut flora that would be found among people consuming a high-fat diet which would contribute to obesity. A control group of mice was fed a normal diet to serve as comparison. The mice in each group then mated, and their eventual offspring then spent three weeks with their mothers while being observed to see how behaviour and microflora was affected.

It was found that the offspring from the mice laden with high-fat foods exhibited social impairments, including very little engagement with peers. Meanwhile, a test called ribosomal RNA gene sequencing found that the offspring of the mice that were fed a high-fat diet housed a very different bacterial gut environment to the offspring of mice fed a normal diet.

Discussing the result, co-author Shelly Buffington was keen to stress just how significant the findings were: “By looking at the microbiome of an individual mouse we could predict whether its behaviour would be impaired.”

In an effort to understand whether the variation in microbiome was the reason for differences in social behaviour, the researchers paired up control group mice with high-fat diet mice. Peculiarly, mice eat each other’s faeces, which is why researchers kept them together for four weeks. The high-fat diet mice would eat the faeces of the normal mice and gain any microflora they held. Astonishingly, the high-fat diet mice showed improvements in behaviour and changes to the microbiome, hinting that there may be a species of bacteria making all the difference.

After careful examination using a technique called whole-genome shotgun sequencing, it was found that one type of bacteria – Lactobacillus reuteri – was far less prevalent in the offspring of high-fat diet mice than the offspring of normal-diet mice.

Discussing the method and finding, Buffington said: “We culture a strain of Lactobacillus reuteri originally isolated from human breast milk and introduced it into the water of the high-fat diet offspring. We found that treatment with this single bacterial strain was able to rescue their social behaviour.”

What the Lactobacillus reuteri seemed to be doing was increasing production of oxytocin, a hormone which is known by various other names such as the “trust hormone”, or the “love hormone”, because of its role in social interactions.

The results of the experiment showing that Lactobacillus reuteri can influence social behaviour are profound findings. Though the work would need to be transferred from mice studies to full human clinical trials to see if this could be applied to autistic people, the impact of adding Lactobacillus reuteri to the gut flora of mice can’t be underestimated. It seems then, for now, that research will go with the gut.

Photo: André Spicer
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“It’s scary to do it again”: the five-year-old fined £150 for running a lemonade stand

Enforcement officers penalised a child selling home-made lemonade in the street. Her father tells the full story. 

It was a lively Saturday afternoon in east London’s Mile End. Groups of people streamed through residential streets on their way to a music festival in the local park; booming bass could be heard from the surrounding houses.

One five-year-old girl who lived in the area had an idea. She had been to her school’s summer fête recently and looked longingly at the stalls. She loved the idea of setting up her own stall, and today was a good day for it.

“She eventually came round to the idea of selling lemonade,” her father André Spicer tells me. So he and his daughter went to their local shop to buy some lemons. They mixed a few jugs of lemonade, the girl made a fetching A4 sign with some lemons drawn on it – 50p for a small cup, £1 for a large – and they carried a table from home to the end of their road. 

“People suddenly started coming up and buying stuff, pretty quickly, and they were very happy,” Spicer recalls. “People looked overjoyed at this cute little girl on the side of the road – community feel and all that sort of stuff.”

But the heart-warming scene was soon interrupted. After about half an hour of what Spicer describes as “brisk” trade – his daughter’s recipe secret was some mint and a little bit of cucumber, for a “bit of a British touch” – four enforcement officers came striding up to the stand.

Three were in uniform, and one was in plain clothes. One uniformed officer turned the camera on his vest on, and began reciting a legal script at the weeping five-year-old.

“You’re trading without a licence, pursuant to x, y, z act and blah dah dah dah, really going through a script,” Spicer tells me, saying they showed no compassion for his daughter. “This is my job, I’m doing it and that’s it, basically.”

The girl burst into tears the moment they arrived.

“Officials have some degree of intimidation. I’m a grown adult, so I wasn’t super intimidated, but I was a bit shocked,” says Spicer. “But my daughter was intimidated. She started crying straight away.”

As they continued to recite their legalese, her father picked her up to try to comfort her – but that didn’t stop the officers giving her stall a £150 fine and handing them a penalty notice. “TRADING WITHOUT LICENCE,” it screamed.


Picture: André Spicer

“She was crying and repeating, ‘I’ve done a bad thing’,” says Spicer. “As we walked home, I had to try and convince her that it wasn’t her, it wasn’t her fault. It wasn’t her who had done something bad.”

She cried all the way home, and it wasn’t until she watched her favourite film, Brave, that she calmed down. It was then that Spicer suggested next time they would “do it all correctly”, get a permit, and set up another stand.

“No, I don’t want to, it’s a bit scary to do it again,” she replied. Her father hopes that “she’ll be able to get over it”, and that her enterprising spirit will return.

The Council has since apologised and cancelled the fine, and called on its officials to “show common sense and to use their powers sensibly”.

But Spicer felt “there’s a bigger principle here”, and wrote a piece for the Telegraph arguing that children in modern Britain are too restricted.

He would “absolutely” encourage his daughter to set up another stall, and “I’d encourage other people to go and do it as well. It’s a great way to spend a bit of time with the kids in the holidays, and they might learn something.”

A fitting reminder of the great life lesson: when life gives you a fixed penalty notice, make lemonade.

Anoosh Chakelian is senior writer at the New Statesman.