Abnormal age-related changes of plasma antioxidant proteins in schizophrenia

Albumin and bilirubin are metal-binding proteins, shown to possess free radical scavenging properties, and may thus be selective antioxidants. In the present study we examined whether individual plasma antioxidants such as albumin and bilirubin, which significantly contribute to total antioxidant status (TAS), are reduced in patients with schizophrenia. We prospectively studied plasma antioxidant proteins, i.e. albumin and bilirubin, in male veteran schizophrenic patients using a within-subject, repeated measures, on-off-on haloperidol treatment design, as well as age- and sex-matched healthy volunteers. Male patients with schizophrenia either during haloperidol treatment (n=46) or in a drug-free condition (n=35) had significantly lower levels of both plasma albumin and bilirubin compared with age- and sex-matched healthy volunteers (n=31). Such reductions of plasma antioxidant proteins in schizophrenic patients appear to be age-related changes, in contrast to those observed in healthy volunteers. On the other hand, levels of plasma albumin and bilirubin were not significantly affected by haloperidol treatment, haloperidol withdrawal, or length of drug-free period. Moreover, plasma TAS was not influenced significantly by cigarette smoking, even though it may selectively decrease plasma bilirubin but not albumin levels. The present findings, taken together with our previous results of reduced plasma TAS and uric acid, as well as an increased Red blood cell superoxide dismutase, lend further support to the hypothesis that a defect in the antioxidant defense system exists in schizophrenia that may lead to oxidative damage.