We investigated the relationship between serum tumor necrosis factor-alpha (TNF-α) levels and psychopathological symptoms, clinical and socio-demographic characteristics and antipsychotic therapy in individuals with schizophrenia. TNF-α levels were measured in 90 patients with schizophrenia and 90 healthy controls matched by age, gender, smoking status, and body mass index. The Positive and Negative Syndrome Scale (PANSS) was used to assess the severity of psychopathology in patients. No significant differences in TNF-α levels were detected between the patients and controls (p=0.736). TNF-α levels were not correlated with total, positive, negative, general, or composite PANSS scores (all p>0.05). A significant negative correlation was observed between TNF-α levels and the PANSS cognitive factor (ρ=-0.222, p=0.035). A hierarchical regression analysis identified the cognitive factor as a significant predictor of the TNF-α level (beta=-0.258, t=-2.257, p=0.027). There were no significant differences in TNF-α levels among patients treated with different types of antipsychotics (p=0.596). TNF-α levels correlated positively with the age of onset (ρ=0.233, p=0.027) and negatively with illness duration (ρ=-0.247, p=0.019) and antipsychotic treatment duration (ρ=-0.256, p=0.015). These results indicate that TNF-α may be involved in cognitive impairment in schizophrenia, and would be a potential clinical-state marker in schizophrenia.
Keywords: immune system; psychopathology; schizophrenia; tumor necrosis factor-alpha.