Exploring the Ecological Mechanisms of the Association between Gut Microbiome and Depression

Depression is a prevalent mental health disorder that affects almost all age groups, and is the leading cause of death and disability among young population age under 25. People with depression usually suffer from much higher risk of suicide compared with those without depression, and impairment of cognitive, learning and social functions caused by depression seriously lowers the quality of life of patients and increases social burden. To achieve the goal of healthy ageing, it is important to improve outcomes of depression treatment and prevent relapse of recurrent depressive episodes. However, many of patients lack adequate response to treatment and there is a risk of relapse among remitted patients. Our study aims to further investigate the association between gut microbiome and depression symptoms and provide evidence for future studies to develop novel therapy to improve treatment outcomes of patients with depression. It is critical to understand the how a microbiome system forms and changes (i.e., the ecological mechanisms) in response to specific environment (i.e., change of disease status of the host). In ecology, the complexity of an ecological system is mostly measured by diversity. A commonly referred theoretical framework of ecological mechanisms is proposed by Vellend et al. that an ecological system is usually formed by the processes of selection, drift, dispersal and speciation. This framework has been utilized to explore the association between gut microbiome and obesity, diabetes, and inflammatory diseases,but it has not been used to investigate the association between gut microbiome and depression.