Termed the ‘second brain’, our bodies have a completely separate nervous system, which carries 500 million neurons and stretches to nine meters, from oesophagus to anus. Historically thought to be for controlling digestion, the enteric nervous system (ENS), is now being associated with an influential role in physical and mental wellbeing. Embedded in the gut wall, the ENS is extremely complex, with the ability to work with the brain, and independently, to allow us to sense environmental threats and influence our individual response.
In this way, without individual awareness, our guts are “thinking” for us. This is re-iterated by Michael Gershon at the Columbia-Presbyterian Medical Center, New York, who states: “A lot of the information that the gut sends to the brain affects wellbeing, and doesn’t even come to consciousness.”
The gut, like the brain, houses neurotransmitters. Dopamine, the signalling molecule associated with pleasure, acts in the gut to transmit messages between neurons, coordinating muscle contractions in the colon. Meanwhile, the mood-enhancing serotonin, known to regulate appetite and sleep, is produced in the gut for its role of repairing damaged liver and lung cells after being transported to the blood. Furthermore, it is important for heart development and regulation of bone density.
Still, the causal relationship between gut and health has only recently been scientifically established. Notably, there is mounting evidence linking autism and fluctuations in the diversity and abundance of the gut microbiome.
Factors like prenatal infection and pre-birthing complications are recognized for altering the microbial colonization of the developing infant and known to be implicated in autism. This is supported by the prevalence of gastrointestinal distress in patients, as well as research illustrating that mice lacking any gut bacteria depict social deficits and repetitive behaviours akin to those seen in those who suffer from the disorder.
The ENS has the ability to act autonomously; furthermore, 90 per cent of signals flowing through the vagus nerve come directly from the ENS. Subsequently, a wealth of information arises from our guts, acting in connection to the brain. Stimulation of the vagus nerve has been noted as an effective treatment for chronic depression that has been left untreated following therapeutic measures.
In essence, novel research is continuously reiterating the association of the gut and brain in health. A significant number of people suffering from certain gastrointestinal illnesses also portraying psychiatric disorders, and the unearthing that problems with the ENS create implications in numerous conditions; it is clear that the second brain deserves greater recognition.
Enhancing knowledge of the ENS could craft significant successes in understanding and treating various brain conditions, such as Alzheimer’s and Parkinson’s. With that, health could be depicted in the light of Gershon’s remarks: “The inside of your gut is really the outside of your body.”