Stress, Psychiatry and the Intestinal Microbiome
December 3, 2018
Humans develop disease from many different routes including toxic exposures, genetics, poor nutrition, injury, microbial exposures and much more. One of the biggest risk factors for the development of disease is mental stress. Specifically, chronic stress of the psyche is traumatic to the cellular machinery of the body like the protective telomere tails of DNA strands or the functioning intestinal microbiome.
What I find fascinating is that stress, the brain, and the microbiome are intimately linked. In this two part series,
we are going to look at the this association and what we can do to positively support it. The gut is often called the second brain and that is not by accident as there is a large network of nerves throughout our gut called the enteric nervous system. This is thought to be why we can have a "gut reaction". Roughly 80-90% of the bodies supply of the neurotransmitter serotonin resides in the gut. The functions of serotonin include regulating mood, sleep, appetite, gut motility and various cognitive functions.
Why would such an important neurotransmitter be concentrated in the gut? My medical school professors taught me to believe that the intestine is a place of digestion and assimilation, not thinking and feeling.
It turns out that the fields of neurology, epigenetics and microbiology are working together to answer this question and change the narrative.
What we now know to be true is that there is a bidirectional flow of communication that uses neural, hormonal and immune routes to achieve the goal of bridging the worlds of the brain, our bacterial friends and the rest of our sensing and feeling body. This is called the gut-brain axis. (Cryan et. al. 2012) What is even more astounding is that the microbes that reside in our intestines have direct and profound effects on how our brain works. (Mayer et. al. 2014) Evidence continues to accumulate that bacteria and viruses that live within us have elegant ways of hijacking our neurological system and changing who we are and how we feel.
Whether it is autism spectrum disorders, anxiety, depression or chronic pain, a significant portion of the cause can now be attributed to the gut microbiome. I am a believer that the autism spectrum disorders, in part, will be shown to be a result of insults to the maternal fetus dyad via epigenetic alterations and microbial imbalances in the gut and brain.
To keep this clear of the leap of faith world, let us look at a few studies. In 2017, Dr. Sangdoo Kim and her team showed that mice with abnormal bacterial signatures in their microbiome birthed offspring with autism like features. This effect could be prevented by treating the animals with antibiotics and killing these pathogenic bacterial species. (Kim et. al. 2017)
Further studies have shown that restoration of intestinal microbes via probiotic therapy or fecal transplantation can ameliorate the anxiety burden. (Mayer et. al. 2017) Collins and colleagues showed that anxiety could be induced by transplanting the bacteria from an anxious mouse to a happy mouse. (Collins et. al. 2013) The strain of probiotic known as Lactobacillus which is commonly found in over the counter probiotics can increase the receptor for GABA, a calming neurotransmitter, which in turn reduces anxiety and depressive type behaviors. (Bravo et. al. 2011)
There is a large body of evidence that chronic stress can alter the microbes in the gut, disrupt the intestinal barrier leading to food reactions, increased immune activation and changes in our behavior. (Cryan et. al. 2012)
Pausing here to recap some hard science, we have a clear picture that the world of psychiatry and neurology used to believe that depression, anxiety and other neurobehavioral disorders were hard wired genetic defects or broken brain chemistry. This could not be farther from the truth!
The intestinal microbiome and the bacteria within play a large role in human mental health. The scientific evidence is clear that we need to prevent damage to the microbiome and stop altering the bacteria within negatively.
What I know to be true now is that psychiatric and neurobehavioral disorders are NOT the effects of broken brains in the vast majority of cases. They are NOT the effects of choice for many people in the beginning of the disease genesis. They are NOT hardwired and permanent. Even poorly treated and previously thought irreversible diseases like Alzheimers dementia are NOT so. The groundbreaking scientific work of Moshe Szif (nature versus nurture), Dale Bredesen (Alzheimers reversal specialist) and Terry Wahls (Multiple sclerosis reversal) have opened a locked door to a whole new world of hope and understanding for resolution of devastation to the brain.
What these pioneers are doing is rewriting medicine by not accepting the current status of disease etiology and instead starting from the roots of the tree to find the breakpoint that began the disease. They are working on patients microbiomes through diet alterations, working on brain pathways through epigenetics via stress reduction training and so much more.
How does mental stress play into this reality?
Most forms of stress in the acute phase are often life extending as they elaborate cassettes of genes in our DNA that are hanging out in order to come to play when life gets difficult. I think of temperature shock protein genes here. They are there to preserve our species and help us procreate, our two main driving forces of existence. Where stress becomes an issue is in the chronic unremitting state. Study after study has shown that this persistence of stress breaks down all levels of our neural, hormonal and immunological communication pathways. We all know this to be true as we often get ill with infectious organisms following a prolonged stressful event.
If we accept that the microbiome is affected by stress and the microbiome in turn affects our mood and cognition, then it behooves us to pay particular attention to what disturbs the microbiome and thus our psyche as well.
Next week: How do we protect the microbiome from perturbation and disease?
To a healthy gut microbiome - Nazdrowje,
Cryan Nature Reviews Article
Mayer Journal of Neuroscience Article
Kim Nature Article
Collins Current Opinions in Microbiology
Bravo PNAS Article
Newsletter on Autism
Endocrine Disruptors Newsletter
AAAAI Food Allergy Site