Differences in gut microbiome composition between persons with chronic schizophrenia and healthy comparison subjects

Intestinal microbiome and gut-brain axis have been receiving increasing attention for their role in the regulation of brain/behavior and possible biological basis of psychiatric disorders. Several recent clinical studies have linked the microbiome with neuropsychiatric conditions, although the literature on schizophrenia is quite limited. This study investigated gut microbiome composition in 50 individuals, including 25 persons with chronic schizophrenia and 25 demographically-matched non-psychiatric comparison subjects (NCs). Stool samples were collected and assayed using 16S rRNA sequencing of the V4 region. Examination of unweighted UniFrac and Bray-Curtis dissimilarity revealed significant community-level separation in microbiome composition between the two subject groups. At the phylum level, Proteobacteria were found to be relatively decreased in schizophrenia subjects compared to NCs. At the genus level, Anaerococcus was relatively increased in schizophrenia while Haemophilus, Sutterella, and Clostridium were decreased. Within individuals with schizophrenia, abundance of Ruminococcaceae was correlated with lower severity of negative symptoms; Bacteroides was associated with worse depressive symptoms; and Coprococcus was related to greater risk for developing coronary heart disease. Our findings provide evidence of altered gut microbial composition in persons with chronic schizophrenia and suggest a need for larger and longitudinal studies of microbiome in schizophrenia.