Hippocampal interneurons are abnormal in schizophrenia.

Area of Science:

• Neuroscience
• Psychiatry
• Cell Biology

Background:

• Hippocampal dysfunction is a key feature of schizophrenia.
• The specific cellular changes underlying this dysfunction are not fully understood.

Purpose of the Study:

• To investigate the hypothesis that hippocampal interneurons are abnormal in schizophrenia.
• To determine if the total number of hippocampal neurons in the pyramidal cell layer is altered in schizophrenia.

Main Methods:

• Analysis of hippocampal specimens from 13 schizophrenia patients and 20 healthy controls.
• Quantification of total neurons, somal volume, and specific interneuron populations (somatostatin- and parvalbumin-positive).
• Measurement of mRNA levels for somatostatin, parvalbumin, and glutamic acid decarboxylase 67.

Main Results:

• The total number of hippocampal neurons in the pyramidal cell layer was normal in schizophrenia.
• A significant reduction in the number of somatostatin- and parvalbumin-positive interneurons was observed.
• Decreased mRNA expression levels for somatostatin, parvalbumin, and glutamic acid decarboxylase 67 were found.

Conclusions:

• The findings provide strong evidence for a specific defect in hippocampal interneurons in schizophrenia.
• These interneuron deficits have significant implications for understanding hippocampal dysfunction in schizophrenia.
• The study supports emerging models of schizophrenia pathophysiology involving interneuron abnormalities.