20 Aug 2019

Potential link between gut bacteria and ADHD

From Afternoons, 1:41 pm on 20 August 2019

Children with ADHD who took micronutrients had lower levels of a bacteria linked to the disorder, and a healthier range of bugs in their gut, a pilot study has found.

The study – done in collaboration between University of Otago, Christchurch geneticists and the University of Canterbury's Mental Health and Nutrition laboratory – was recently published in Nature's Scientific Reports journal.

The study monitored 10 children with ADHD taking the micronutrients – which are a dietary supplement of vitamins and minerals – above the recommended daily dosage over a 10-week period. Another seven children with ADHD were given a placebo treatment.

It found that those taking micronutrients had a significantly richer gut microbiome community, and significantly fewer Bifidobacterium.

Escherichia coli - one of the many species of bacteria present in the human gut

Photo: Public domain

“The key interesting result that we found was that the abundance of the classes of bacteria, called Bifidobacterium, actually showed a significant decrease only in the treatment group and that’s interesting because that’s been identified by overseas researchers as being one of the potential decontributors towards ADHD symptoms,” lead researcher Dr Aaron Stevens told Jesse Mulligan.

While the research is still in its early days, Dr Stevens says the findings are positive.

“That in particular is a very new area of research, and there is very limited investigation into it. They [researchers and international studies] have found that there’s a handful bacteria that are continually being identified as being potential modulators or decontributors towards ADHD, at the moment the field doesn’t really understand why that is, or pathways through which it might be acting.

“But what they’re identifying is that these bacteria, such as the one we identified … called Bifidobacterium, are continually popping up as being important and they’re going to likely be the decontributors that future research will build upon to identify how they’re actually contributing.”

He says because it was a small study, it’s hard to say whether more or less of the bacteria is beneficial.

“International research … identified that children with ADHD tend to have a substantially decreased community, so there’s less variety in their mycobiome. What we are investigating was how this dietary supplement can change the community structure of the mycobiome.”

Professor Julia Rucklidge, who leads the Mental Health and Nutrition laboratory, says scientists are now wondering whether people who suffer from specific psychiatric symptoms, like ADHD ones, have a different bacterial composition than those who don't have these symptoms.

“More research is needed with larger groups of people with ADHD, and to understand the potential effect of diet, medications, age, ethnicity and gender on the results that have been reported,” she says.

Prof Rucklidge says the pilot study follows a study of almost 100 children investigating the impact of vitamin-mineral treatment on the aggression and emotional regulation in children with ADHD.

That study found micronutrients improved overall function, reduced impairment and improved inattention, emotional regulation and aggression in the children.

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