An excellent review article was published recently in Nature Translational Psychiatry, emphasizing the potentially very important link between the bacteria living in our gut and the health of our brain. The authors completed a sweeping review of the literature, referencing over 250 articles, highlighting the growing recognition that the microbiome is implicated in many psychiatric conditions, including depression, anxiety, bipolar, schizophrenia, and post-traumatic stress disorder (PTSD).
The researchers discuss how various molecules produced by gut bacteria, including both harmful (lipopolysaccharide, LPS) and beneficial (small chain fatty acids, SCFAs) molecules, amongst many others, can modulate the integrity of the gut lining (making it leaky) as well as affect the local immune system. When there is increased leakiness of the gastrointestinal lining, along with activation of the immune system with the resulting effect of generating circulating inflammatory mediators, both bacterial as well as human molecules can then affect the blood brain barrier, which protects our brain, and contribute to dysfunction in the brain that likely contributes to psychiatric disorders.
While the authors did any incredibly good job of analyzing potential mechanisms to explain the relationship between the microbiome and the brain, there was a fair amount of overlap in terms of proposing potential mechanisms for specific psychiatric disorders, which unfortunately does not provide the level of detail that would be helpful in thinking about targeted interventions or treatments (with probiotics, for example, or dietary interventions) for the various mental health conditions.
The authors do admit there are many factors at play, stating in their article, “This variability likely reflects differences in genetic background, environmental exposures, diet, metabolic status, and developmental timing,” and advocate for future research to more clearly delineate exact mechanisms and “clinically actionable interventions.”
I discuss the microbiome in my book Optimized, and the many techniques you can use to enhance your microbiome and, therefore, your physical and mental wellbeing!
