Reduced serum TNF alpha level in chronic schizophrenia patients with or without tardive dyskinesia

Mounting evidences have demonstrated the association of altered immune factors with neurodevelopmental and pathological progression of schizophrenia. However, whether immune factors play any role in the pathogenesis of tardive dyskinesia (TD) has been underexplored. To our best knowledge, ours is among the piloting studies examining the association of TNF alpha with extrapyramidal symptoms of schizophrenic patients so far.

The aim of this study was to assess the clinical significance of serum TNF alpha level in chronic schizophrenia, especially its potential association with TD.

Serum TNF alpha level was measured in a sandwich enzyme-linked immunosorbent assay (ELISA) from 46 medicated chronic schizophrenia patients with TD, 43 chronic schizophrenia patients without TD, and 43 healthy control subjects. The symptoms of schizophrenia were assessed by the positive and negative syndrome scale (PANSS).

Chronic patients both with TD and without TD had significantly lower serum level of TNF alpha than controls (TD=9.5±2.1pg/ml, non-TD=10.7±1.8pg/ml, control=37.8±3.4pg/ml, p<0.001). Compared to patients without TD, TD patients showed marginally significant reduction in the serum TNF alpha level (p=0.05). The reduced TNF alpha level was not significantly affected by daily dose or duration of antipsychotic drugs (p>0.05). Serum TNF alpha level was negatively correlated with the PANSS total score in the whole schizophrenia patients (p<0.01), but no significant association with TD severity was observed.

Our results suggested that at chronic stage, serum TNF activity is associated with psychopathology of schizophrenia patients, but whether it can be a biomarker for TD needs further clarification in the future.