Significantly lower levels of hypoxanthine and creatinine in the CSF of patients with schizophrenia

Levels of hypoxanthine, xanthine, uric acid (UA), homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA) and creatinine were measured in the cerebrospinal fluid (CSF) of 49 patients with schizophrenia and 21 healthy controls. Twenty-six of the patients were first admissions who had never received antipsychotic treatment. We found significantly lower levels of hypoxanthine in the CSF of the patients (p=0.02) – the mean±SD was 3.09±0.57 μmol/l for controls and 2.72±0.69 μmol/l for patients with schizophrenia. Female schizophrenics had significantly lower levels of creatinine in their CSF than controls (p=0.01) –the mean±SD was 3.04±0.56 μmol/l for female controls and 2.67±0.74 μmol/l for females with schizophrenia. There were also numerous positive correlations between the substances in the CSF. But these positive correlations between metabolites in the CSF need to be interpreted with caution as it could be caused by a similar grade of dilution. The finding of lowered levels of hypoxanthine in schizophrenia is interesting in the light of the purine hypothesis of schizophrenia – which proposes that schizophrenia, at least in part, may be caused by an imbalance in adenosine signaling. But also because of the recent interest the xanthine-oxidase inhibitor, and hypoxanthine isomer, allopurinol has gained as an adjuvant treatment in schizophrenia.