Main idea: Although the clinical and preclinical studies are sparse and not very consistent, they suggest that sex differences in the gut microbiota may play an essential role in some neuropsychiatric conditions.
Sex differences are often observed in psychiatric patients. The microbiota-gut-brain axis hypothesis arises to explain some aspects of the complex pathophysiology of neuropsychiatric disorders. The communication between the brain and the gut is bidirectional and may impact the entire system’s homeostasis. The findings are still incipient, and more research is needed to confirm or refute the hypothesis. The connection between gut and brain includes neuroanatomic communication, neuroendocrine pathways, immune system, bacteria-derived metabolites, hormones, neurotransmitters, and neurotrophic factors.