Reduction of the parahippocampal gyrus and the hippocampus in patients with chronic schizophrenia.

Background: There have been many studies reporting reduced volume of the hippocampus or other limbic structures in patients with schizophrenia, but the literature is inconsistent.

Aims: To compare patients with either first-episode or chronic schizophrenia with controls using high-resolution volumetric magnetic resonance imaging (MRI) scans.

Method: Thirteen patients with first-episode schizophrenia, 27 with chronic schizophrenia and 31 controls had 1.5 mm coronal slices taken through the whole brain using a spoiled-grass MRI acquisition protocol.

Results: The parahippocampal gyrus was reduced significantly on the left side in patients with chronic schizophrenia compared with controls for both male and female patients, whereas the hippocampus was reduced significantly on both sides only in female patients. There were no significant reductions in any structure between patients with first-episode schizophrenia and controls.

Conclusions: Volumetric reduction seen in patients with chronic schizophrenia may be due to an active degenerative process occurring after the onset of illness.