Dysbiosis: A Potential Precursor to the Development of a Depressive Disorder

Background: Although previous investigations have indicated that gastrointestinal pathologies facilitate the occurrence of mood disorders, there is a lack of studies based on data from clinical practice. The aim of this study was to investigate the incidence of depression in patients with dysbiosis. Methods: Adult patients (≥18 years) from 1193 general practices in Germany between January 2005 and December 2018 with an initial diagnosis of dysbiosis documented anonymously in the Disease Analyzer database (IQVIA) were analyzed. The incidence of depression diagnoses as a function of dysbiosis was calculated and multivariate regression models were applied. Results: This study included 552 patients with and 552 patients without dysbiosis. Within five years of the index date, 20.5% of patients with dysbiosis and 5.5% of individuals without dysbiosis had been diagnosed with depression (p < 0.001). Dysbiosis was found to be significantly associated with the incidence of depression (HR: 2.85 (95% CI: 2.00−4.04)). This association was slightly stronger in men (HR: 3.54) than in women (HR: 2.61) and was more pronounced in the age group >60 years (HR: 4.43). Conclusions: We identified dysbiosis as a risk factor for developing depression within 5 years after the index date. This risk seems to be higher in male than in female patients.