Investigating the Gut Microbiome in Psychiatric Illness

Abstract

The global burden of mental health disorders is rising with the world health organization recently having recognized major depressive disorder as the leading cause of disability worldwide. Nearly one in five Canadians are now estimated to struggle with a mental health disorder and Generalized Aanxiety Ddisorder (GAD) Mmajor Ddepressive Ddisorder (MDD) and Bbipolar Ddisorder are three of the most prevalent. Despite significant research into the disorders’ cause, the pathophysiology and underlying etiology of these diseases remains largely undiscovered. Recent research has highlighted the potential role of the gut microbiota in mental health, in particular in connection with anxiety. Our research aims to investigate this link in a cohort of GAD, MDD and bipolar patients recruited through the Anxiety Treatment and Research Centre at St. Joseph’s Healthcare in Hamilton, as well as through the University Health Nnetwork in Toronto. 71 GAD, 18 MDD, 17 euthymic MDD and 23 Bipolar patients provided fecal samples from which DNA was extracted, following which the V3 region of the 16S rRNA gene was amplified and sequenced using the Illumina Miseq platform. Sequencing data was analyzed through an in-house pipeline to construct community profiles of patients and age and sex matched healthy controls. My work involved analyzing the data to identify signature organisms that might identify putative disease associated microbial communities for further hypothesis generation about possible roles in disease. Furthermore, an extensive culturing effort was undertaken to identify and characterize some of the Bacteroides strains which were enriched in the GAD patient population. This study presents novel insights into some of the organisms that may be markers for a number of different diseases as well developing a better understanding of the Bacteroides that were correlated with anxiety.