Recent hypotheses suggest that an alteration in the microbiota that sustains inflammation could favor schizophrenia. Resolving intestinal dysbiosis could potentially become a new treatment option.
Schizophrenia, which affects around 0.7% of the world population, is characterized by a wide range of symptoms, such as an alteration in social relationships, cognitive problems, delirium, and hallucinations. The disease results from complex interactions between genes and environmental factors, like maternal infections during fetal development or the consumption of cannabis1.
The role of immunity
The role of an immune imbalance and particularly of a significant inflammation in the development of the disease is being increasingly recognized. As such, the possibility that pro-inflammatory intestinal dysbiosis might be responsible is beginning to be explored2.
The responsibility of the microbiota
Disruptions in the composition of gastrointestinal microbiota have been found in schizophrenic patients3 , as well as an increase in intestinal permeability – particularly through an increase in circulating CD14 levels (marker for bacterial translocation)4,5.
A step towards new treatments?
20 to 30% of schizophrenic patients do not respond or barely respond to currently available antipsychotic treatments1. Action on the gut-brain axis, particularly by rebalancing the microbiota to reduce inflammation, is starting to be considered6. Studies have shown that the administration of probiotics can have an immunomodulating effect, by acting on the plasma concentrations of neurotrophic factors7 , but for the moment no treatment of this type has demonstrated clinical effectiveness.
1- Inserm. Schizophrénie [en ligne]. Dossier réalisé en collaboration avec Marie-Odile Krebs. Mai 2014. Disponible à l'adresse : http://www.inserm.fr/thematiques/neurosciences-sciences-cognitives-neurologie-psychiatrie/dossiers-d-information/schizophrenie
2- Ellul P. et al. Focus sur la schizophrénie : infections, auto-immunité et dysbiose intestinale, L'INFORMATION PSYCHIATRIQUE, 10/2016 (Volume 93), p. 797-802. https://www.cairn.info/load_pdf.php?ID_ARTICLE=INPSY_9210_0797
3- Sherwin E et al. May the Force Be With You: The Light and Dark Sides of the Microbiota-Gut-Brain Axis in Neuropsychiatry. CNS Drugs 2016 ; 30 : 1019-41. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5078156/pdf/40263_2016_Article_370.pdf
4- Severance EG et al. Seroreactive marker for inflammatory bowel disease and associations with antibodies to dietary proteins in bipolar disorder. Bipolar Disord 2014 ; 16 : 230-40. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4075657/pdf/nihms591287.pdf
5- Nemani K et al. Schizophrenia and the gut-brain axis. Prog Neuropsychopharmacol Biol Psychiatry 2015 ; 56 : 155-60. https://www.ncbi.nlm.nih.gov/pubmed/?term=Nemani+K%2C+Hosseini+Ghomi+R%2C+McCormick+B%2C+Fan+X.+Schizophrenia+and+the+gut-brain+axis.+Prog+Neuropsychopharmacol+Biol+Psychiatry+2015+%3B+56+%3A+155-60.
6- Dickerson FB et al. Effect of probiotic supplementation on schizophrenia symptoms and association with gastrointestinal functioning: a randomized, placebo-controlled trial. Prim Care Companion CNS Disord. 2014; 16(1)10.4088/PCC.13m01579. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4048142/
7- Tomasik J, Yolken RH, Bahn S, Dickerson FB. Immunomodulatory Effects of Probiotic Supplementation in Schizophrenia Patients: A Randomized, Placebo-Controlled Trial. Biomark Insights. 2015 Jun 1;10:47-54. doi: 10.4137/BMI.S22007. https://www.ncbi.nlm.nih.gov/pubmed/26052224