Gut Microbiome Link To ADHD Reinforced In Scientific Review

The paper, published in Neuroscience, reviewed more than 280 studies and found mounting evidence that the immune system, neuroinflammation and a disturbed balance of bacteria in the gut played a role in ADHD symptoms.

Lead author Naomi Lewis said two types of bacteria were particularly implicated: the Bacteroides species and Faecalibacterium.

“What we found was that there are compositional differences in the types of bacteria in the gut that may contribute to inflammation, brain functioning differences, and symptoms, in ADHD,” Ms Lewis said.

In particular, certain Bacteriodes species that may improve the integrity of the intestinal barrier were found in less abundance in people with ADHD.

“Similarly, low levels of Faecalibacterium in the gut, also implicated in ADHD, has been linked with inflammatory conditions.

“Systemic inflammation cuts through the blood-brain barrier and can cause neuroinflammation, potentially from a very young age.”

Ms Lewis said although ADHD was highly heritable, there were still environmental links to the severity of symptoms.

“It’s important to remember there is a lot of complexity here, so no one thing is causing ADHD,” she said.

“Genetics still play a major role, but this research suggests you may want to look at the best support for minimising inflammation, particularly going into pregnancy.”

“The research in this space is still quite limited, but what we do know is that gut health plays an enormous role in mental health and neurological conditions,” Ms Lewis said.

“Gut bacteria can affect neurological processes in the brain, impacting behaviour and emotional regulation.”

Co-author, UniSC Nutrition and Dietetics senior lecturer Dr Anthony Villani, said the review added to the global understanding on the impact of the gut microbiome on mental health.

“Most studies have found children with ADHD have poorer diets, with more added sugars and more processed foods compared to those without.

“But whether that is cause or affect we don’t know, but there is certainly a need for more research,” Dr Villani said.

Across the hundreds of papers reviewed, the evidence supports adopting lifestyle choices that nurture the gut microbiome.

This includes minimising antibiotics, stress, and alcohol, saturated fats and refined sugar, eating more fibrous foods such as whole grains, fruits, vegetables, legumes and nuts – or adopting a Mediterranean-type diet as much as possible.

The paper is called Gut dysbiosis as a driver of neuroinflammation in attention deficit/hyperactivity disorder: A review of current evidence

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