Person-to-Person Microbiota Transmission Can Influence Depression and Anxiety in Newly Married Couples: Six-Month Interim Results

Background Oral microbiota dysbiosis and salivary cortisol are associated with depression and anxiety. Bacterial transmission can occur between spouses. Aims We explored whether oral microbiota, salivary cortisol and a combined depression-anxiety (DA) phenotype affiliated in newly married couples. Methods The researchers administered validated Persian versions of the Pittsburgh Sleep Quality Inventory (PSQI), Beck Depression Inventory-II (BDI-II), and Beck Anxiety Inventory to 1740 couples, who had been married during the past six months. The investigators compared 296 healthy control spouses with 296 cases. Data analysis used appropriate statistical methods. Results After six months, at the phyla level, we identified a significant decrease in Firmicutes and Actinomycetota abundance and an increase in Bacteroidetes, Proteobacteria, Fusobacteria and Patescibacteria abundance in healthy spouses married to an insomniac with DA-phenotype, showing that oral microbiota were significantly changed and became similar to that of participant’s spouse, (i.e., if the spouse had DA-phenotype, then composition of oral microbiota became similar to their spouse DA-phenotype, p <0.001). These changes parallelled alterations in salivary cortisol, depression and anxiety scores. Linear discriminant analysis (LDA) showed that relative abundances of Clostridia, Veillonella, Bacillus and Lachnospiraceae were significantly higher in insomniacs with DA-phenotype than healthy controls ( p <0.001). Results remained significant after controlling for confounders. The formal mediation analysis confirmed these outcomes. We observed distinct analogous gender differences for oral microbiota pattern, salivary cortisol level, and depression and anxiety scores. Conclusions Microbiota transamination between two people in close contact with one another partially mediated depression and anxiety.