BY: DR. JASON BUSH
The Gut-Brain Axis is a line of communication linking our brain to the microbiome in our large intestine. This connection is thought to be bidirectional, which is intriguing because it begs the question: Are your thoughts really your own?
Research supporting the Gut-Brain Axis is still in the early stages, meaning that ground-breaking research is rapidly emerging, helping to define this nascent field.
One such study was recently published in the journal Nature Microbiology, which described a correlations between mental health and both the microbes present and metabolites produced in the gut microbiome. Microbes constitute the inhabitants of the microbiome while the metabolites are the chemicals these microbes normally produce. Researchers are interested in studying both because the metabolites produced by the microbes are likely the communication signals employed by the Gut-Brain Axis. This sort of study could help to unlock the ‘secret language’ the microbes use to communicate with their human hosts.
Faecalbacterium, Dialister, and Coprococcus, bacteria which are commonly found in the gut microbiomes of healthy individuals, were found at lower levels in individuals suffering from depression. Increased production of the metabolite GABA by microbes was associated with depression. GABA plays a central role in brain physiology, generally acting to inhibit the activity of other neurons. Conversely, microbe-produced DOPAC, a breakdown product of the excitatory neurotransmitter DOPA, was positively associated with good mental health quality.
The mechanisms by which these microbes and metabolites coordinate to influence mental health remains to be determined, especially given the difficulty that most blood-borne substances have in reaching the brain. These effects are likely mediated via the Vagus nerve, which connects the brain to the gut and other organs. Indeed, many scientists consider the Vagus nerve to be the ‘highway’ that makes up the Gut-Brain Axis.
While we don’t fully understand the effect the gut microbiome has on our mental health, early studies suggest that there is indeed a link. Future research will help refine our understanding of ‘self’, change how we reflect on our thoughts and emotions, and ultimately guide how we might be able to manipulate the composition of the gut microbiome to promote a healthy mental state.