Depression, Serotonin, and the Mind-Gut Connection
Neuroscientists now think of the gut as a "second brain"; it independently controls your digestive processes and is in constant conversation with your main brain. What do they talk about? Depression, theorizes Dr Emeran Mayer.
18 October, 2016
We all feel things in our gut – intuitions that give us subtle physiological alerts, stress and anxiety that unsettle us, bad reactions to food, and conversely feelings of contentment from the right food, or flutters from an exciting experience. But according to Dr Emeran Mayer, what we feel is just a small fraction of what’s going on in a region of our body that is still quite mysterious – even to the experts.
<p>In his new book, <i>The Mind-Gut Connection,</i>, Dr Mayer writes: "Your gut has capabilities that surpass all our other organs and even rival your brain. It has its own nervous system, known in scientific literature as the enteric nervous system, or ENS, and [is] often referred to in the media as the "second brain.""</p>
<p>As Mayer describes, this second brain consists of about 100 million nerve cells sandwiched between layers of the gut running all the way from the esophagus to the end of the large intestine. This ‘second brain’ and our regular brain use the same neurotransmitters and are connected through neural, endocrine, and immune pathways, so it truly is an integrated intelligent system with information flowing in both directions.</p>
<p>What makes the second brain unique from other organs is that – in animals at least – when it’s separated from the main brain it continues to pilot its complex activities on its own. </p>
<p>The system is extremely interesting to researchers because of this independent streak, and the effect that it may have on our mental health. After his many years of research, Mayer humbly says it’s "highly plausible" that there is a connection between the gut and mental health conditions such as depression. Scientists from the University of North Carolina have found that gut bacteria produce neurotransmitters like serotonin, dopamine and GABA, all of which have associations with our mood. Often the medications people with depression take are designed to adjust the uptake of these neurotransmitters, a treatment scientists at the time designed thinking only of the brain, but it may now also have implications in the microbiome.</p>
<p>What makes it even more intriguing is that more than 95% of our body’s serotonin is produced and stored in the gut in specialized enterochromaffin cells, says Dr Mayer, adding: "By far the largest store of the molecule that plays such a big role in modulating our mood and our wellbeing – also appetite, pain sensitivity – is stored in the gut."</p>
<p>In recent years, the microbiome has come to the fore of scientific research, hinting at the wide reach of its sway over the body and mind. There is still a long, long way to go in understanding direct causations, but when that happens, there is no doubt our comprehension of this second brain will affect our well-being and quality of life in a big way. </p>
<p>Dr Emeran Mayer's most recent book is <a href="https://www.amazon.com/Mind-Gut-Connection-Conversation-Impacts-Choices/dp/0062376551"><i>The Mind-Gut Connection: How the Hidden Conversation Within Our Bodies Impacts Our Mood, Our Choices, and Our Overall Health</i></a></p>.<p><a href="https://www.amazon.com/Mind-Gut-Connection-Conversation-Impacts-Choices/dp/0062376551"><img height="150" src="%5Cr%5Cnhttps://s3.amazonaws.com/edge-misc-assets/Book+Covers/Emeran+Mayer+1.jpg" width="225"></a></p>
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