IL-1α: Interleukin-1α, IL-6: Interleukin-6, TNF-α: Tumor Necrosis Factor-α. MDD: Major Depressive Disorder. ^Two-Way ANOVA. Significance p < 0.05

Associations between cytokines, measures of adiposity, cardiac health and psychological symptoms:

In the total cohort, IL-1α and IL-6 were significantly correlated with all psychometric measures, while TNF-α was correlated significantly with anxiety and hostility but not with depression, stress or GSI (Table 3). In contrast, none of the pro-inflammatory cytokines (IL-1α, IL-6, TNF-α) correlated with adiposity or cardiac health measures. When analyses were performed separately per diagnostic group and per sex, there were differential correlations. In the MDD group, IL-6 was correlated with anxiety, hostility, GSI, and stress, and TNF-α with hostility, while IL-1α did not correlate with any psychological symptoms. In the control group, IL-1α was correlated with hostility, IL-6 negatively with depression and stress, and TNF-α negatively with depression. Among females, IL-6 correlated with all of the psychometric measures, TNF-α correlated with anxiety, hostility, GSI and stress and IL-1α did not show any significant correlations. In contrast, among males, IL-1α correlated with depression, hostility, GSI and stress, while IL-6 and TNF-α did not correlate with any psychological symptoms.

Table 3 : Spearman’s correlations of pro-inflammatory cytokines (IL-1α, IL-6, TNF-α) with psychometric measures per cohort, group (MDD and control) and sex (females and males)