The Gut-Brain Axis in Healthy Females: Lack of Significant Association between Microbial Composition and Diversity with Psychiatric Measures

Abstract

ObjectiveThis study examined associations between the composition and diversity of the intestinal microbiota and measures of depression, anxiety, eating disorder psychopathology, stress, and personality in a group of healthy adult females.MethodsFemale participants (n = 91) ages 19–50 years with BMI 18.5–25 kg/m2 were recruited from central North Carolina between July 2014 and March 2015. Participants provided a single fecal sample and completed an online psychiatric questionnaire that included five measures: (i) Beck Anxiety Inventory; (ii) Beck Depression Inventory-II; (iii) Eating Disorder Examination-Questionnaire; (iv) Perceived Stress Scale; and (v) Mini International Personality Item Pool. Bacterial composition and diversity were characterized by Illumina sequencing of the 16S rRNA gene, and associations were examined using Kendall’s tau-b correlation coefficient, in conjunction with Benjamini and Hochberg’s False Discovery Rate procedure.ResultsWe found no significant associations between microbial markers of gut composition and diversity and scores on psychiatric measures of anxiety, depression, eating-related thoughts and behaviors, stress, or personality in a large cohort of healthy adult females.DiscussionThis study was the first specifically to examine associations between the intestinal microbiota and psychiatric measures in healthy females, and based on 16S rRNA taxonomic abundances and diversity measures, our results do not suggest a strong role for the enteric microbe-gut-brain axis in normal variation on responses to psychiatric measures in this population. However, the role of the intestinal microbiota in the pathophysiology of psychiatric illness may be limited to more severe psychopathology.

Daily Changes in Composition and Diversity of the Intestinal Microbiota in Patients with Anorexia Nervosa: A Series of Three Cases

“…Classification of 16S rRNA forward sequence reads was performed in duplicate with two pipelines: QIIME version 1.5.0, using previously described quality filtering, OTU clustering, and taxonomy assignment methods (Caporaso et al, 2010;Kleiman et al, 2017); and version 2.10.1 of the RDP classifier with a threshold of a 50% RDP score (Wang, Garrity, Tiedje, & Cole, 2007). Both pipelines yielded similar results, with strong separation between patients' samples.…”

Reconceptualizing anorexia nervosa

“…In this sample, we also observed a significant correlation between mood and microbial diversity such that lower diversity was associated with higher self‐report depression scores . Of note, this was not observed in an independent sample of healthy controls who had a much more restricted range of responses on the mood measures . Together, these observations raised the question of whether this aspect of the microbe–gut–brain axis is only detectable at more extreme levels of psychopathology.…”

“…98 Of note, this was not observed in an independent sample of healthy controls who had a much more restricted range of responses on the mood measures. 99 Together, these observations raised the question of whether this aspect of the microbe-gut-brain axis is only detectable at more extreme levels of psychopathology. A recent large population investigation provided intriguing and replicated evidence for an association between the gut microbiome and quality of life and depression.…”

The gut microbiome in psychiatry: A primer for clinicians

“…A small investigation suggested evidence of dysbiosis in anxiety and depression patients and paired with increased gut permeability (Stevens et al, ). While another study failed to find an association between anxiety and depressive symptoms and microbial diversity in healthy females (Kleiman et al, ). A recent study in generalized anxiety disorder revealed reduced microbial richness and diversity in drug‐naïve ( n = 12) and medicated patients ( n = 28) compared to controls ( n = 36; H. Y. Jiang et al, ).…”