The influence of perceived stress on the human microbiome

Abstract

Objective: Microbial dysbiosis, a shift from commensal to pathogenic microbiota, is often associated with mental health and the gut-brain axis, where dysbiosis in the gut may be linked to dysfunction in the brain. Many studies focus on dysbiosis induced by clinical events or traumatic incidents; however, many professions in austere or demanding environments may encounter continuously compounded stressors. This study seeks to explore the relationship between microbial populations and stress, both perceived and biochemical.

Results: Eight individuals enrolled in the study to provide a longitudinal assessment of the impact of stress on gut health, with four individuals providing enough samples for analysis. Eleven core microbial genera were identified, although the relative abundance of these genera and other members of the microbial population shifted over time. Although our results indicate a potential relationship between perceived stress and microbial composition of the gut, no association with biochemical stress was observed. Increases in perceived stress seem to elucidate a change in potentially beneficial Bacteroides, with a loss in Firmicutes phyla. This shift occurred in multiple individuals, whereas using cortisol as a stress biomarker showed contradictory responses. These preliminary data provide a potential mechanism for gut monitoring, while identifying targets for downstream modulation.

Keywords: 16S rRNA; Cortisol; Gut–brain axis; Microbiome; Stress.

Fig.1

Perceived and biochemical stress of each participant over time. The cortisol (blue) and perceived stress scale (red) were taken weekly, whereas the sleep score (black) and OQ−45 (gold) were taken bimonthly. The maximum and minimum points generated from these data were used to choose time points of interest for further microbial analysis

Fig.2

Diversity of the gut microbiome for each participant over time. Gut microbiome diversity is displayed for the time points corresponding to the minimum and maximum perceived stress levels (top panel), the time points corresponding to the minimum and maximum cortisol levels (middle panel), and all time points measured (bottom panel). In the instances where the time points corresponding to the minimum or maximum did not yield high quality microbiome data, the time point with the next lowest (for the minimum) or next highest (for the maximum) perceived stress or cortisol levels were used.