The gastrointestinal tract and the intestinal microflora are directly connected to the central nervous system via gut-brain axis. Dysbiosis of the intestinal ecosystem, i.e. the propagation of pathogenic bacteria and yeast-like fungi and reducing the abundance of beneficial microbes. Pathogenic microorganisms carry out putrefaction (proteolytic protein digestion). Moreover, the pathogens generate a number of toxic compounds (ammonia, phenols and amines) and gases (hydrogen, carbon dioxide and methane). Pathogenic bacteria also produce a number of unfavourable enzymes in the large intestine, being involved in the synthesis of mutagenic and carcinogenic products, promoting not only cancer processes, but also the development of a number of other diseases.
The intestine is directly connected to the central nervous system via vagus nerve. As a consequence, all toxic compounds and metabolites produced by pathogenic bacteria in the intestine are transported to the brain, leading to a significant deterioration of its functioning, progressive deterioration of mood and other psychiatric disorders.
Moreover, the proliferation of pathogenic gut microbiota is destructive to the intestinal barrier integrity. Disrupted gut barrier creates the second gate of penetration for harmful substances and food antigens into the blood system, from where they reach directly to all tissues and organs. Thus by means of inflammation, antigens affect the structure of the nervous system. Additionally, pro-inflammatory cytokines synthesis reduce the availability of serotonin (the so-called “happiness hormone”), while generating the toxic metabolites of tryptophan. Such pathway leads to a strong deterioration of mood, and consequently even to the development of depression, anxiety and organic differences within the nervous system.
Of note, in patients with mood disorders and depression gastrointestinal disorders, most commonly abdominal pain, bloating, constipation and gastrointestinal reflux are frequently described. They are due to disruptions in the intestinal microbiota composition and consequently intestinal barrier integrity.
Evaluation of the intestinal microflora composition and administration of the appropriate probiotic supplementation should be of the highest priority to eliminate the cause of worsening mood. In turn, the investigation of latent hypersensitivity of IgA and IgG – dependent types, will enable the implementation of a targeted diet that limits inflammation within the central nervous system.
In case of mood disorders, the following tests are recommended: