Hippocampal volume in schizophrenia and its relationship with risperidone treatment: a stereological study

The purpose of this study was to assess the significance of the hippocampal volume differences and its relation with risperidone treatment in schizophrenia. In schizophrenic patients who were on risperidone treatment (n = 11) and in healthy volunteers (n = 11), volumes of the hippocampi were estimated using magnetic resonance images (MRIs). A detailed systematic series of coronal MRIs of the entire brain (3 mm thickness, T(1)-weighted, TR/TE 400/10 ms) was obtained for each subject. All estimations were done according to Cavalieri's method by a modified point-counting grid placed on surface areas of hippocampal slices. The mean right and left hippocampal volumes in schizophrenics and control subjects were 1059.4 and 1003.2 mm(3), and 1780.1 and 1589.1 mm(3), respectively. The corresponding coefficients of errors were 0.05 and 0.068, and 0.059 and 0.081, respectively. The volumes of left and right hemispheres were not significantly different in both schizophrenic patients and controls (p > 0.05). However, a statistically significant difference (p < 0.05) was found between hippocampal volumes of the schizophrenic patients and controls. In conclusion, the hippocampal volume of the schizophrenic patients is significantly smaller than of the healthy controls. The patients who responded well to risperidone treatment had significantly greater hippocampal volumes than the patients who did not respond properly. Thus, hippocampal volume may be a predictor of the treatment response of schizophrenics to risperidone.