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 alteration s in the anatomy of the corpus callosum in schizophrenia, this study examin ed the anterior commissure in post mortem brains (n = 14 female control pat ients, 15 male control patients, II female schizophrenic patients, 15 male schizophrenic patients). Methods: Measures were made of the cross-sectional area of the anterior com missure 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 schizophr enic 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 fo r fiber density there was a significant gender X diagnosis interaction (p = .026), corresponding to a reduction in female, but nor male patients with s chizophrenia. Conclusions: The reduction in density of fibers in the anterior commissure is consistent with an alteration of interhemispheric connectivity in schizo phrenia, but the restriction of the finding to women emphasizes the relevan ce of gender to understanding the nature of the hemispheric interaction. (C ) 1999 Society of Biological Psychiatry.