Mood disorders, depression and bipolar disorder affect people of all ages and sometimes cause severe mental distress. Effective treatments exist and ongoing research is evaluating the impact of the intestinal microbiota on these disorders.
According to the World Health Organization (WHO), depression affects more than 350 million people worldwide. It sometimes causes severe mental distress that can lead to suicide and is the first cause of professional and social disability in the world. More women than men are affected1. Mood disorders include depressive and bipolar disorders.
Perturbed stress responses
Life events, like the loss of a spouse, a job or a separation, are associated with an increased risk of mood disorders. However, vulnerability to depression, which is partly genetic, exists for each individual2 . Thus, each person with a parent who suffers from depression has a two to four times higher risk of having a depressive episode in his/her lifetime. Defective regulation of the stress-response system, with abnormally high secretion of cortisol, the stress hormone, can also induce a depressive state. Lastly, a microbiota–intestine–brain axis communicates via multiple pathways (parasympathetic nervous system, immune, blood) and participates in the pathophysiology of mood disorders3 . Recent research on the intestinal microbiota yielded findings showing associations between dysbiosis and depression.
Therapy is based on antidepressants combined with cognitive behavioral therapy for depressive disorders and mood-stabilizing drugs2,4 . A microbiota role may be promising. Results of a recent randomized, double-blind, placebo-controlled study showed that daily intake by healthy volunteers of a combination of probiotics—Lactobacillus helveticus and Bifidobacterium longum—improved mood and lowered anxiety levels5.
1 – OMS, avril 2016, la dépression http://www.who.int/mediacentre/factsheets/fs369/fr/
2 – INSERM, dépression, août 2014, http://www.inserm.fr/thematiques/neurosciences-sciences-cognitives-neurologie-psychiatrie/dossiers-d-information/depression
3 – Cryan JF, Dinan TG. Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour. Nat Rev Neurosci. 2012;13:701-12.
4 - Haute Autorité de Santé (HAS), décembre 2010, prise en charge d'un trouble bipolaire, http://www.has-sante.fr/portail/upload/docs/application/pdf/2011-01/ald_23_gp_troublebipolaire_web.pdf
5 - Messaoudi M et al. Assessment of psychotropic-like properties of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in rats and human subjects. Br J Nutr. 2011;105:755-64. https://www.ncbi.nlm.nih.gov/pubmed/20974015