Brain-Gut-Microbiota Axis in Mood and Cognition: Impact of Psychobiotics

The microbiome appears to play a role in modulating a wide range of systems including the hypothalamic-pituitary-adrenal axis and stress response, the immune system, neurotransmission, tryptophan metabolism, and serotonin synthesis, all processes which are highly relevant to the regulation of mood and cognition. The majority of studies investigating the effects of probiotics on mood and anxiety symptoms have been performed in healthy subjects and predominantly investigate Lactobacillus and Bifidobacterium strains. Changes in diet can rapidly and reproducibly alter microbiome composition and it is eminently plausible that the gut microbiome represents the link in the observed association between food and mood. Diet was a major determinant of microbiota diversity with a loss of diversity and increased frailty evident in those in long-stay care in comparison with community dwellers. Several case-control studies have reported altered gut microbiota composition in patients with depression.