The gut reaction to couples' relationship troubles: A route to gut dysbiosis through changes in depressive symptoms

Abstract

The gut microbiota plays a role in a wide range of diseases and disorders, with low microbial diversity and richness emerging as notable risk factors. This longitudinal study addressed the impact of marital quality (assessed by the Couples Satisfaction Index) on changes in depressive symptoms, and gut diversity, richness, and permeability. On two occasions an average of 90 days apart, 162 people provided stool and blood samples, and completed questionnaires. Depressive symptoms, assessed by the Center for Epidemiological Studies Depression Scale (CES-D), increased from visit 1 to visit 2 in those with clinically significant relationship problems, in contrast to the lack of change among their more satisfied counterparts. These changes in depression were consequential: the gut microbiota's diversity and richness decreased in tandem with the increase in depressive symptoms. Lower relationship satisfaction also foreshadowed increases in lipopolysaccharide binding protein from visit 1 to visit 2, reflecting greater translocation of bacterial endotoxin from the gut to blood circulation, a process that fuels inflammation. Lower diversity and richness provide a pathway from depressive symptoms and marital distress to subsequent health risk.

Keywords: Couples; Depression; Gut microbiota; Intestinal permeability; Lipopolysaccharide binding protein; Marriage.

Figure 1:

Bray-Curtis distances using presence/absence data to quantify beta diversity within-subject/between-visit, within-couple (distance averaged over visits), and between individuals and all other same-sex individuals who were not the spouse (averaged over other individuals and over visit). Smaller Bray-Curtis distance corresponds to higher similarity. Large square is the group mean. ***p<0.001

Figure 2:

Predicted change in depression (CES-D) as a function of marital satisfaction (CSI). Results from mixed effects models controlling for age, gender, BMI, antidepressant use, and baseline depression. Shading indicates 95% confidence intervals.

Figure 3:

Changes in (A) alpha diversity (Shannon Index) and (B) richness as a function of change in depression (CES-D). Superimposed line is the regression line at the average level of covariates (age, gender, BMI, antidepressant use, baseline depression, and the baseline outcome level). Shading indicates 95% confidence intervals.