The relation between depression, anxiety and psychotropic drugs on the gut microbiome

Internalizing disorders, such as depression and anxiety, are multifactorial conditions influenced by host and environmental factors. Internalizing traits and states, such as neuroticism and negative affect, are often associated with these disorders. Recently the role of the gut microbiome in relation to these factors has been demonstrated in human and animal studies. In this study we aimed to explore the relations of the gut microbiome with current and lifetime internalizing disorders (depression and anxiety) and internalizing traits and states (neuroticism and negative affect), and whether psychotropic drugs could explain this association. We also aimed to determine whether the gut microbiome could be predictive of major depressive disorder approximately 5 years later. We used data on the gut microbiome and the use of psychotropic drugs in 7,656 participants of the Dutch population cohort Lifelines. In general, we observed that internalizing disorders, especially depressive disorders, were significantly (FDR<0.05) associated with several bacterial taxa, while drug associations were moderate. Dysthymia in particular had a profound impact on the gut microbiome, suggesting that chronic depressive disorders have a greater influence on the gut microbiome than episodic depressive disorders or anxiety disorders.