In a study by Lawrence Berkeley National Laboratory, or Berkeley Lab, researchers found that the gut microbiome, or the entirety of microorganisms in the gut, can partially mediate the effects of genetics on anxiety.
The researchers determined this association through studying mice, a species believed to have a similar gut-brain axis, or GBA, to humans. The amount of Ruminococcaceae, a bacteria found in the gut, was significantly greater in high-anxiety mice compared to low-anxiety mice, according to the study. Researchers found it was negatively correlated with “percent of time in light.”
“(Natural genetic variation could) ultimately lead to identification of biomarkers to predict anxiety and to identify microbial targets which could be potentially be exploited to modify the GBA and treat anxiety and other neurological disorders,” said study co-author Antoine Snijders in an email.
Experiments using mice allow researchers to control variables, such as diet and lifestyle, that they cannot control in human experiments, according to Snijders. Previous studies found that imbalances in the gut and fecal matter transplantation could lead to depression in mice.
The researchers used a technique called genome-wide association analysis to look at the association between genetic makeup and more easily observable traits.
“In genome-wide association analysis, specific genetic variations… across the genome are associated with specific phenotypic traits (in our case anxiety and the abundance levels of specific gut microbes),” Snijders said in the email.
Although researchers found a correlation between Ruminococcaceae and anxiety, the bacteria also negatively correlated with the severity of mice anxiety, implying that it may not have a direct role in causing anxiety, according to the study.
These results suggest that researchers could use the presence of specific bacteria as an indication of anxiety or other disorders.
“This study lays the foundation for future research to evaluate treatments for anxiety taking into account both host genome and microbiome,” Snijders said in the email. “Our next steps are aimed at identifying the causal mechanisms that explain the relationship between specific gut microbes and anxiety-like phenotypes in mice.”
