Abnormalities of the hippocampus, a seahorse-shaped brain region involved in learning and memory, may play a role in the psychotic symptoms and cognitive deficits of schizophrenia. Prior studies have suggested that overall hippocampal volume and neuron number are normal in schizophrenia – but whether there are more subtle abnormalities remains unclear.
Using human postmortem brain samples, Christine Konradi and colleagues compared total number of hippocampal neurons and interneurons (neurons that connect and typically inhibit the action of neighboring neurons) of subjects with schizophrenia to those of unaffected brains. While total hippocampal neuron number was similar, the schizophrenia group showed a significant reduction in the number of neurons expressing somatostatin and parvalbumin – protein markers of interneurons. Levels of mRNA for these markers were also reduced in the schizophrenia group.
The results, reported July 13 in Schizophrenia Research, provide evidence for a specific defect in hippocampal interneurons in schizophrenia and may suggest new targets for drug treatments for the condition.
The research was supported by grants from the National Institute of Mental Health.