Visceral Adiposity Is Associated with Elevated Interleukin-1 Receptor Antagonist Levels and Anxiety Symptoms in Schizophrenia

Schizophrenia spectrum disorders are associated with visceral obesity and chronic low-grade inflammation. However, the role of inflammatory mediators in anxiety and depressive symptoms remains unclear. This study aimed to investigate associations between body fat distribution, circulating inflammatory mediators, and affective symptoms in schizophrenia. In this cross-sectional study, 67 patients with schizophrenia were assessed using the Positive and Negative Syndrome Scale (PANSS), with anxiety (G2) and depression (G6) items analyzed separately. Body composition, including visceral fat area (VFA), percent body fat (PBF), and skeletal muscle mass (SMM), was measured using bioelectrical impedance analysis. Serum concentrations of 38 immune mediators were determined using Multiplex technology. Multivariable regression analyses were performed to identify predictors of affective symptoms. Among all analyzed immune mediators, only interleukin-1 receptor antagonist (IL-1ra) was consistently associated with adiposity measures, showing the strongest correlation with VFA (rho = 0.53; p < 0.001). Higher VFA was independently associated with greater anxiety severity (β = 0.32; p = 0.017), whereas depressive symptom severity was associated with higher PBF (β = 0.32) and younger age (β = −0.25). Visceral adiposity was associated with anxiety severity in schizophrenia and may represent a potential marker warranting further investigation. The observed association between IL-1ra and adiposity supports a potential immunometabolic link between metabolic status and affective symptoms in this population.