Peripheral inflammation and neurocognitive functioning in early psychosis: Specific associations of TNF-α and IL-6...

Cognitive deficits and immune system dysregulation are core features of psychotic disorders. Among inflammatory markers, interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α) have been linked to both psychosis pathophysiology and related cognitive impairments.

We investigated associations among IL-6, TNF-α, and neurocognitive performance in 107 participants: individuals at clinical high risk for psychosis (CHR-P, n = 35), first-episode psychosis (FEP, n = 39), and healthy controls (HC, n = 33). Assessments included memory, processing speed, executive function, and social cognition. Cytokines were measured from fasting serum samples. Analyses included ANOVA, correlations, and multivariate regressions controlling for age, sex, IQ, group, and symptom severity.

TNF-α levels were significantly elevated in FEP compared to CHR-P (p = 0.0251); IL-6 differences were non-significant. FEP showed poorer performance in multiple cognitive domains, especially social cognition. CHR-P individuals exhibited intermediate profiles between FEP and HC in cognition. In adjusted regression models, IL-6 was significantly associated with undermentalization on the MASC task (β = 0.28, p = 0.0337) and showed a trend-level association with slower processing speed (β = 0.98, p = 0.075). TNF-α levels predicted poorer facial emotion recognition (β = -1.37, p = 0.0022). IQ and group were significant covariates in most models.

Our findings suggest that peripheral inflammation, particularly IL-6 and TNF-α, may selectively impact social cognitive functioning in early psychosis. Though modest, these associations highlight potential inflammatory contributions to functional impairment and support further investigation of immunological targets in early intervention.