The size and fiber composition of the anterior commissure with respect to gender and schizophrenia

Background: In light of evidence for deviations in asymmetry and alterations in the anatomy of the corpus callosum in schizophrenia, this study examined the anterior commissure in post mortem brains ( n = 14 female control patients, 15 male control patients, 11 female schizophrenic patients, 15 male schizophrenic patients). Methods: Measures were made of the cross-sectional area of the anterior commissure in the midsagittal plane. In addition, the fiber density and fiber number were measured in a subset of cases ( n = 10 female control subjects, 10 male control subjects, 8 female schizophrenic patients, 9 male schizophrenic patients), using the Palmgren silver stain and stereological methods. Results: In control subjects, fiber numbers were greater ( p = .024) in women than men. In schizophrenia, the cross-sectional area was unaffected, but for fiber density there was a significant gender × diagnosis interaction ( p = .026), corresponding to a reduction in female, but not male patients with schizophrenia. Conclusions: The reduction in density of fibers in the anterior commissure is consistent with an alteration of interhemispheric connectivity in schizophrenia, but the restriction of the finding to women emphasizes the relevance of gender to understanding the nature of the hemispheric interaction.