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

A substantial body of evidence implicates TNF-alpha (TNF alpha) and TNF alpha-related signaling pathways in the pathophysiology of schizophrenia. The current study examined the relationship between TNF alpha serum levels and both psychopathological as well as cognitive symptoms in schizophrenia. Serum TNF alpha 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 TNF alpha levels were measured by sandwich enzyme-linked immunosorbent assay (ELISA). TNF alpha 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 TNF alpha levels and the PANSS total score (p < 0.01). Additionally, TNF alpha 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 TNF alpha levels as a significant predictor of scores on the general psychopathology subscale of the PANSS. The significant relations observed in the current study between TNF alpha and the PANSS and its subscales suggest that immune disturbance may be involved in the psychopathology and cognitive deficits of schizophrenia.