Relationship between the random forests interpretation model, relative abundance of [Actinobacteria, Lentisphaerae, Verrucomicrobia] and posttraumatic stress disorder (PTSD) scores (Clinician Administered Posttraumatic Stress Disorder Scale for DSM-5 (CAPS), Total Score). Posttraumatic stress disorder was negatively correlated with the relative abundance of Actinobacteria, Lentisphaerae, and Verrucomicrobia phyla. In other words, PTSD diagnosis was associated with decreased abundance of these phyla (Pearson’s r = −.387; P = .035). Percentages in parentheses indicate the percent relative abundance of Akkermansia; Akkermansia was below the threshold of detection for all other participants. Sample sizes, PTSD participants, n = 18; TE controls, n = 12). *P < 0.05, Student’s t-test.