Association between metabolic syndrome, diabetes mellitus, inflammation and cognitive dysfunctions in schizophrenia: a cross-sectional analysis.

Metabolic syndrome (MetS) and diabetes mellitus (DM) are frequent in schizophrenia (SCZ) and have been linked to cognitive impairment and low-grade inflammation. In this cross-sectional study of adults with DSM-5 SCZ (N = 218; SCZ = 103, SCZ+MetS = 62, SCZ + DM = 53), we quantified interleukine-6 (IL-6) and C-Reactive Protein (CRP) and evaluated their associations with Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) cognitive domains and routine metabolic measures using multivariable models. Results revealed that SCZ + DM showed lower attention and delayed memory scores than SCZ and SCZ+MetS. No between-group differences were observed for immediate memory, visuospatial function, or language. IL-6 was highest in SCZ + DM, intermediate in SCZ + MetS, and lowest in SCZ. CRP did not differ significantly between groups. Across the cohort, higher IL-6 and fasting glucose were associated with lower attention and delayed memory. We conclude that DM status and higher IL-6 were most consistently associated with poorer attention and delayed memory in SCZ. Given the cross-sectional design, these findings reflect associations and may be influenced by treatment and residual confounding. Longitudinal studies with broader cytokine panels are warranted.