Inositol levels are decreased in postmortem brain of schizophrenic patients

Background: A previous study reported decreased levels of inositol in frontal cortex of postmortem brain from bipolar patients and suicide victims. The aim of the present study was to test the specificity of this finding. Methods: Inositol and the enzyme that synthesizes it, inositol monophosphatase, were measured in postmortem brain tissue from frontal and occipital cortex and cerebellum from 10 schizophrenic patients and the previously reported controls. Inositol levels were assayed gas- chromatographically as trimethylsilyl derivatives with mannitol as an internal standard. Inositol monophosphatase activity in brain homogenates was measured as the difference between phosphate release from inositol-1- phosphate in the absence and in the presence of Li⁺. Results: Inositol was significantly reduced in all three areas in the schizophrenic patients' brains; inositol monophosphatase was unchanged. Postmortem interval did not correlate with inositol levels and did not differ between control group and schizophrenic patients. Conclusions: These results suggest an abnormality of second messenger precursor availability in common with schizophrenia and affective psychopathology.