From the Editor

It takes guts to be mentally ill: Microbiota and psychopathology

Current Psychiatry. 2018 September;17(9):4-6

References

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But don’t overlook the importance of diet. It is a major factor in shaping the composition of the microbiota. What we eat can have a preventative or reparative effect on neuroimmune or neuroinflammatory disease. An emerging body of evidence suggests that the diet and its effects on the gut microbiota can modify a person’s genes by epigenetic mechanisms (altering DNA methylation and histone effects). Probiotics can exert epigenetic effects by influencing cytokines, by producing short-chain fatty acids (SCFAs), by vitamin synthesis, and by producing several well-known neurotransmitters.⁶

The bidirectional trafficking across the microbiome-gut-brain axis includes reciprocal effects. The brain influences the microbiome composition by regulating satiety, the hypothalamic-pituitary axis, and with neuropeptides.⁷ In return, the microbiome conveys information to the brain about the intestinal status via infectious agents, intestinal neurotransmitters and modulators, cytokines, sensory vagal fibers, and various metabolites. Failure of these normal interactions can lead to a variety of pathological processes, including inflammatory, autoimmune, degenerative, metabolic, cognitive, mood, and behavioral adverse effects. Therapeutic interventions for these adverse consequences can be implemented through microbiome manipulations (such as fecal transplants), nutritional strategies, and reinforcement of the enteric and brain barriers.

Alterations in the microbiota, such as by the intake of antibiotics or by intestinal inflammation, can lead to psychiatric disorders.⁸ The following findings link gut microbiome disruptions with several psychiatric disorders:

Schizophrenia prodrome. Fecal bacteria show an increase in SCFAs, which can activate microglia (the initial step in triggering psychosis).⁹ These bacteria have been shown to lead to an increase in choline levels in the anterior cingulate, a known biomarker for membrane dysfunction, which is one of the biological models of schizophrenia.

Schizophrenia—first-episode. A recent study reported abnormalities in the gut microbiota of patients with first-episode psychosis, with a lower number of certain fecal bacteria (including bifidobacterium, E. coli, and lactobacillus) and high levels of Clostridium coccoides. After 6 months of risperidone treatment, the above changes were reversed.¹⁰

Continue to: Another study of fecal microbiota...

It takes guts to be mentally ill: Microbiota and psychopathology

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