Decreased serum TNF-alpha levels in chronic schizophrenia patients on long-term antipsychotics: correlation with psychopathology and cognition.

Objective: A substantial body of evidence implicates TNF-alpha (TNFα) and TNFα-related signaling pathways in the pathophysiology of schizophrenia. The current study examined the relationship between TNFα serum levels and both psychopathological as well as cognitive symptoms in schizophrenia.
Materials and Methods: Serum TNFα levels were assessed in 89 patients diagnosed with schizophrenia and compared to 43 healthy control subjects matched for age and gender. Schizophrenic symptomatology was assessed with the Positive and Negative Syndrome Scale (PANSS), and serum TNFα levels were measured by sandwich enzyme-linked immunosorbent assay (ELISA).
Results: TNFα levels were significantly lower in patients with chronic schizophrenia relative to healthy control subjects (p<0.01). Correlation analysis revealed a significant negative correlation between the TNFα levels and the PANSS total score (p<0.01). Additionally, TNFα levels were significantly negatively correlated with scores on general psychopathology (p<0.01), positive (p<0.05) and cognitive subscales (p<0.05). Stepwise multiple regression analysis identified TNFα levels as a significant predictor of scores on the general psychopathology subscale of the PANSS.
Conclusion: The significant relations observed in the current study between TNFα and the PANSS and its subscales suggest that immune disturbance may be involved in the psychopathology and cognitive deficits of schizophrenia.