OBJECTIVE: Glycogen synthase kinase-3 (GSK-3) is a protein kinase that is highly abundant in the brain. It is involved in signal transduction cascades of multiple cellular processes, particularly neurodevelopment. In an attempt to explore possible involvement of GSK-3β in psychiatric disorders, the authors examined its levels in postmortem brain tissue.METHOD: Western blot analysis was performed to measure GSK-3β in the frontal cortex of 14 schizophrenic patients, 15 patients with bipolar disorder, 15 patients with unipolar depression, and 14 normal comparison subjects.RESULTS: GSK-3β levels were 41% lower in the schizophrenic patients than in the comparison subjects. Other diagnostic groups did not differ from the comparison subjects.CONCLUSIONS: These results are consistent with the notion that schizophrenia involves neurodevelopmental pathology. It remains to be investigated whether the active fraction of GSK-3β, or its activity, is also low in frontal cortex of schizophrenic patients and if this is also reflected in other brain regions.