The human gastrointestinal tract hosts trillions of microbes, many of which generate molecules that can have an affect on our health and well-being. Scientists have associated a wide variety of diseases with the gut microbiome, which also has a direct connection to the brain through the vagus nerve. The gut microbiome begins to establish itself immediately after birth (or possibly even before). Scientists have now found that the composition of the gut microbiome during childhood can have an influence on whether a person will develop anxiety, depression, or other similar symptoms during middle childhood. The findings have been reported in Nature Communications.
In this work, the researchers used data that was collected as part of the Growing Up in Singapore Towards Healthy Outcomes (GUSTO) study. This effort collected health data from Singaporean children, such as stool samples (to analyze the composition of the gut microbiome) at 2 years; MRI scans at 6 years; and behavioral observations at 7.5 years. For this work, the investigators focused on data from 55 children.
The researchers looked for various brain connections in the MRI scans at 6 years that were then linked to behavioral issues that were reported at 7.5 years of age. The gut microbiome composition data was then connected to the brain data. This study indicated that when children carried higher levels of Clostridiales order and Lachnospiraceae family bacteria, they were more likely to develop internalizing symptoms, a term that refers to a variety of conditions including anxiety and depression, during middle childhood.
The composition of the microbiome in early life was connected to changes in brain network connectivity in areas that relate to emotion, as well internalizing symptoms in middle childhood.
The researchers suggested that the bacteria in the gut could influence brain circuitry that is related to emotional health in childhood.
When children with symptoms of anxiety and depression are not treated, their conditions may persist and lead to mental health challenges in adolescence and adulthood, said study senior author Dr. Bridget Callaghan, an associate professor at UCLA, among other appointments.
"By linking early-life microbiome patterns with brain connectivity and later symptoms of anxiety and depression, our study provides early evidence that gut microbes could help shape mental health during the critical school-age years," Callaghan added.
Future work may explore whether there are causal links between groups of bacteria like Clostridiales and Lachnospiraceae and mental health issues, as well as whether they can be altered. Studies have already identified links between Clostridiales and Lachnospiraceae bacteria and mental health disorders in adults.
"We need to figure out what species within these larger groups are driving the findings. Once we have that information, there are relatively straightforward ways to change the microbiome, like probiotics or diet, that we could use to address issues," said Callaghan.
Sources: University of California Los Angeles, Nature Communications