Association Between Circulating Cytokines and Psychosomatic Syndromes in Patients with Mood Disorders

elevated levels of pro-inflammatory cytokines are frequently observed in mood disorders, but their relationship with psychosomatic symptomatology remains underexplored. This study aimed to examine whether interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) are associated with psychosomatic syndromes in patients with major depression (MD) and bipolar depression (BD), and whether these associations are moderated by sex.

seventy-seven outpatients with MD or BD were assessed using the Diagnostic Criteria for Psychosomatic Research-Revised (DCPR-R) and the Patient Health Questionnaire-15 (PHQ-15) to evaluate psychosomatic symptoms. Depression and mania severity were measured with the Beck Depression Inventory-II (BDI-II) and the Mania Rating Scale (MRS). Circulating levels of IL-6 and TNF-α were analyzed. Associations were tested using multivariate regression and mediation analyses, controlling for demographic and health-related variables.

both IL-6 and TNF-α were significantly associated with psychosomatic syndromes (as per DCPR-R) and PHQ-15 scores. IL-6, in particular, showed a strong association with persistent somatization (PS). These relationships remained significant after adjusting for affective-cognitive depressive symptoms and potential confounders. No significant moderating effect of sex was identified. Mediation analyses suggested that psychosomatic syndromes mediate the relationship between inflammatory cytokines and depressive symptomatology.

findings suggest that the link between inflammation and mood disorders is more closely related to psychosomatic syndromes than to mood symptoms alone. Elevated IL-6 levels may reflect somatization processes within depression rather than being directly pro-depressive. Psychosomatic syndromes may thus represent a key clinical and therapeutic target in mood disorders with elevated inflammation.