MEET YOUR OTHER BRAIN
100 Million neurons (brain cells) live in your digestive system.
Your brain contains about 86 billion neurons – nerve cells that carry electrical signals that make up your thoughts, memories, and everything else that makes you you. But the brain isn’t the only place neurons exist. They’re all along your spinal cord too, filtering signals between your brain and your extremities and organs. And you may be surprised to learn there are another 100 million neurons embedded in your digestive system – a network so extensive that scientists have given it a name: the enteric nervous system. You have more neurons lining your digestive tract than in your spinal cord, making this a very big deal.
That’s right – you literally have a “second brain” that lives in your gut.
It may seem odd at first, but when you think about it, you can probably recall instances where your brain and your stomach felt mysteriously aligned, like the sensation of “butterflies in your stomach” when you feel nervous, or nausea when you have to deliver bad news. The second brain doesn’t have any cognitive abilities, of course – it doesn’t actively make decisions or have a thought process. What it does do, in addition to the not inconsequential feat of managing our digestion, is help us assess our state of mind. That can make it a player when it comes to handling certain disease states, including inflammatory conditions.
Part of why we developed so many neurons in our gut is that it allows your brain, busy with so many key bodily functions, to step out of the complex digestive equation. Michael D. Gershon, Professor of Pathology and Cell Biology at Columbia University, is known as the father of neurogastroenterology for his groundbreaking research on the topic. As he puts it, in Scientific American: “The brain in the head doesn’t need to get its hands dirty with the messy business of digestion, which is delegated to the brain in the gut.”
This massive neuron network and the way our enteric nervous system engages with the traditional brain means the “mind-body” connection, sometimes referred to in the abstract, is very real. And when that link is broken or not working properly, the body can respond in ways that are detrimental to your overall health. If your immune system triggers inflammation in response to a problem, but your body isn’t able to shut that response off, your white blood cells will continue the attack – even if they’re attacking healthy cells. This can lead to a number of diseases and health problems.
A strong connection between the mind and body can impact almost every aspect of our overall health, from balance to mood. Have you ever felt physically ill when you’re under a lot of stress at work or at home? It’s not all in your head. Stress can cause your immune system to react as if you’re being physically attacked. Your body releases the “fight or flight” hormone cortisol, increasing your blood pressure, heart rate, and breathing, and making your muscles tense up. These are valuable reactions when you’re actually responding to a physical threat. But experiencing these chemical reactions for a prolonged period of time – as a response to long-term mental or emotional stress – can keep you in a crisis state and negatively affect your health.
Depression is a good example of a condition with a clear mind-body link. Depressive episodes have been associated with high levels of proteins released by the immune system called cytokines, which has led scientists to explore the connection between depression and inflammation. Similarly, bipolar disorder is typically associated with the mind, but may have some roots in the body as well. Nearly a third of people who have been diagnosed with bipolar disorder also experience migraines; both conditions are linked to elevated levels of substances that can cause inflammation.
Research also suggests that our enteric nervous system may at least partially cause emotional shifts that happen in conjunction with inflammatory conditions such as irritable bowel syndrome (IBS), as well as constipation, diarrhea, and general stomach pain.
“For decades, researchers and doctors thought that anxiety and depression contributed to these problems. But our studies and others show that it may also be the other way around,” Dr. Jay Pasricha, director of the Johns Hopkins Center for Neurogastroenterology explained on HopkinsMedicine.org. “These new findings may explain why a higher-than-normal percentage of people with IBS and functional bowel problems develop depression and anxiety.”
The idea that the mind and the body are interconnected when it comes to health has been around since at least the second century. Two thousand years later, it’s finally gaining serious steam in the medical community; top schools with departments devoted to studying the connection include Harvard, Columbia and UCLA.