Relationships between total antioxidant capacity (TAC) and psychopathology in schizophrenia is controversial. Different methodological approaches may be a bias factor.

The aim of this research is to analyze the relationship between psychopathology as individual items and psychopathology as syndromes with the serum TAC concentration in schizophrenic patients.

20 DSM-IV paranoid schizophrenic outpatients were recruited from the psychiatric outpatient's clinic of the University Hospital of the Canary Islands. the severity of schizophrenia symptoms was measured with the Positive and Negative Syndrome Scale (PANSS). Blood samples were collected at 12:00 and 00:00 hours. Relationships between quantitative variables were assessed with the Pearson's correlation coefficient.

There was a significant correlation between the PANSS positive subscale and the nocturnal TAC levels (r=0.527, p< 0.02). the PANSS negative subscale was not correlated with TAC concentrations. Item by item scores of the positive and negative PANSS correlations with nocturnal and diurnal TAC levels revealed that only item 6 (suspicion) of the positive PANSS subscale was significantly correlated with the nocturnal TAC concentrations (r=0,491, p< 0.03). Only item 3 (poor contact) of the negative PANSS subscale was also significantly correlated with the nocturnal TAC concentrations (r=0,516, p< 0.02).

We strongly recommend analyzing not only global scores of psychopathology but individual items scores when researching on biological markers in schizophrenia.

This study was partly supported by a grant (PI: 08/115) of the Fundacion Canaria de Investigacion y Salud (FUNCIS).

None of the authors have conflict of interest to disclose.