The gut-brain connection

The gut-brain connection

Nausea and vomiting are common complaints among migraine patients. Many are confused by this strange symptom. What in the world does digestion have to do with a neurological disorder of the brain? How are the brain and digestive system connected?

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Scientists who study this connection refer to the digestive system as the “gut brain”, “second brain”, or more formally as the enteric nervous system (ENS). The vagus nerve connects the brain stem directly to the ENS, enabling direct communication between the two. No other organ system has such a direct pipeline to the brain. Over 90% of the signals traveling along the vagus nerve are sent from the ENS to the brain. Additionally, the ENS is capable of regulating digestion independently of the brain. This was demonstrated by a study in which researchers severed the vagus nerve of rats only to find that their digestive tracts were still functioning 100%. No other organ system can operate independently of the central nervous system.

The ENS contains over 500 million neurons and 40 neurotransmitters. It produces 50% of the body’s dopamine and over 95% of serotonin. This explains why psychotropic medications often trigger digestive upset as a side effect. These neurotransmitters have also been linked to migraines. Disrupt these neurotransmitters and you will experience digestive, emotional, and physical problems.

The role of stress in pain perception

Have you ever experienced “butterflies” in your gut when nervous? This feeling is a result of blood flowing away from the ENS into your muscles as a result of activating the brain’s Fight or Flight response. Our bodies are very inefficient when it comes to dealing with modern stress.  The Fight or Flight system fires whether the danger is real or perceived. There is no distinction between mortal danger and emotional stress. The body responds exactly the same way.  Heart rate increase, blood flows to the muscles, breathing is shallow, and adrenaline floods the body. As a result we may feel nauseous, dizzy, and think we are having a heart attack. We can experience tunnel vision, difficulty swallowing, and shaky hands. In a life-threatening situation, these changes prepare us to run from danger or stand and fight.  When we experience psychological stress, the changes that normally prepare us to take action are left unused. It can take 30 minutes or longer for our brains to realize the threat was a “false alarm” and even longer for our bodies to return to a non-threatened state. Meanwhile we feel pretty miserable. These dramatic changes could be why so many of us identify stress as a primary migraine trigger.

Increased risk of disease

This alarm system also releases inflammatory cytokines that send the immune system into “high alert”. When our immune system is activated, white blood cells increase, and inflammation occurs throughout the body.  Over time, chronic stress keeps this inflammation going all the time. Unchecked inflammation has been linked to the development of depression, anxiety, high blood pressure, atherosclerosis, autoimmune diseases such as MS or ulcerative colitis, and even cancer. How many times have you gotten a migraine as a result of getting sick? It is possible that increased inflammation resulting from stress triggered both.

The role of diet

Some of these stress responses affect pain perception, making our experience of migraine much worse.  In fact, patients with GI problems (IBS, UC, ulcers, etc.) perceive pain more than those who do not. This is theorized to be caused by the brain’s inability to accurately regulate pain signals that come from the ENS. Essentially, stress makes our pain feel worse. But the news is not all bad. Some types of beneficial bacterial (bifidobacterium and lactobaccilus) help turn off the stress response by shutting down production of cortisol and adrenaline. The typical American diet of highly refined foods and germ-free environment reduces the population of these beneficial gut bacteria. However, a diet rich in wholesome fruits and vegetable can actually support the growth of beneficial bacteria and reduce our pain.

Chronic stress also causes the permanent elevation of hormones that increase your craving for high carb, high fat foods. Giving in to these cravings results in decreased anxiety, improved mood, and stimulates the release of dopamine (the reward neurotransmitter). This is just one more way that stress contributes to the development of obesity. These cravings are similar to the cravings we get during the prodrome phase of migraine. Sometimes we actually crave the very foods that trigger migraine.

How therapy helps

There are some physical symptoms that have been shown to improve with psychotherapy. This isn’t because the problem is “all in your head”. It is because both the brain and the digestive system work together to utilize the body’s Fight or Flight response to perceived threat. There are no medical treatments to correct the “false alarms” that happen as a result of psychological stress. So, when medical treatment alone fails, doctors often recommend psychotherapy to patients. These recommendations are often made with the best of intentions, just not delivered or received well.  Doctors are not therapists, so they often lack the communication skills to explain this complex system effectively enough to patients.

So many patients leave their doctor’s office frustrated, hurt, and feeling abandoned. They rarely follow up on the doctor’s recommendation. When they do, they don’t know enough to ask for a therapist who specializes in chronic health problems. The entire system fails and the patients suffer.

Chronic stress messes up the feedback between ENS and the brain, triggering all kind of physiological and emotional disorders such as anxiety, depression, IBS, headaches, high blood pressure, and much more.  Because the brain and body are so interconnected, you can learn to counteract the negative effects of stress by changing your behaviors and thinking patterns. You can literally change the messages being sent between gut and brain by what you tell yourself.

To begin making this kind of change, you will need to look for a therapist who specializes in behavioral pain management, chronic pain, or health psychology. Expect therapy to focus on cognitive and behavioral strategies to counteract the effects of stress. This won’t be the stereotypical “lay on the couch and talk about my childhood” therapy. Very few counselors actually do that anymore.1-5

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The Migraine.com team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.
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