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It’s a scenario many parents of young children are familiar with: an upset stomach and a trip to the doctor.

Gastrointestinal issues in children aren’t uncommon, but recent research has found that such symptoms in young children could be a red flag for problems with emotional health later in life.

Researchers from Columbia University found that children who experienced adversity early in their life were more likely to experience problems with their gastrointestinal system when compared with their peers. This was then found to have implications for the child’s mental health.

“We found that children who had been exposed to caregiving adversity in their early lives (institutional care abroad, before international adoption) had higher levels of gastrointestinal symptoms than their non-adversity exposed peers, for example stomach aches and pains, constipation, funny feelings in the stomach. Importantly, those gastrointestinal symptoms were also associated with higher levels of anxiety, experienced concurrently, and were predictive of anxiety two years into the future,” Bridget Callaghan, author of the study and a Postdoctoral Research Scientist in the Department of Psychology at the Columbia University told Theravive.

In undertaking their study, the researchers looked at the development of children who had been in institutional care before international adoption and experienced extreme levels of psychosocial deprivation. Previous studies have established separation of parents and child could result in mental health problems. In rats, separating children from their parents results in fear and anxiety, interferes with neurodevelopment and also changes the microbiome.

The researchers examined data from 115 children who were adopted from orphanages or foster care before aged two. They also examined data from 229 children who were raised by their biological parents.

The children who were raised in orphanages or foster care were found to have higher levels of stomach aches, vomiting, nausea and constipation. 

From the children studied, eight children aged seven to 13 were selected from the group who had been adopted, and eight others were selected from the group raised by their biological parents. The researchers then collected stool samples, brain images and behavioural information for the children. Gene sequencing was used to see what microbes were present in each child’s stool samples.

Those who were adopted were found to have a noticeably different microbiome than the children who were raised by their biological parents. The brain scans showed that certain activity within the brain was linked to certain bacteria in the gut. The children who were raised by their biological parents had a more diverse microbiome which is linked to an area of the brain that assists in regulating emotions.   

“We are well aware that stress hormones can influence brain development, and are associated with increased mental health risks. A less appreciated fact is that stress hormones are also intricately connected with the gastrointestinal system. High levels of stress can change our intestinal transit time (making us constipated, or have diarrhea), make our immune system overreact to bacteria in our gut, and are associated with what bacteria survive and flourish in the gut. In other words, stress and adversity is linked to every level of the brain-gut-microbiome axis,” Callaghan told Theravive.

“Studies in rats and mice have also shown us that manipulating certain bacteria in the gut can influence brain development, as well as anxiety and depression symptoms. So we have a lot of smoking guns that link adversity, the gut microbiome, and mental health, but we are still trying to understand how all of these pieces fit together in humans, and how this might operate across development.”

Callaghan and her colleagues are furthering their research in a larger-scale study involving 60 children living in New York City. They expect to have their results later this year.

“We are currently trying to establish the generalizability of the findings to different samples, and making some very good progress on that front. Another area we are working on, is attempting to understand the mechanisms underlying the link between adversity, gastrointestinal symptoms, the microbiome, and anxiety in humans. This involves more studies in human samples, but also working with non-human animals to better understand what is going on at the molecular and circuit level,” she said. 

“Knowing how generalizable the findings are will help us to make concrete recommendations to gastroenterologists, pediatricians, and psychiatrists. One of the exciting future implications of these data, and others like it, are the manipulations of gastrointestinal bacteria might eventually be helpful as an aide in treating mental health problems like anxiety and depression; the data from rodent studies is really promising here, as are some studies in adult humans. Although there is a long way to go before we learn how to properly and responsibly harness the potential of this system, we are making headway.”