Original Articles

The effects of gender on grey matter abnormalities in major psychoses: a comparative voxelwise meta-analysis of schizophrenia and bipolar disorder

E. Bora^a1 c1, A. Fornito^a1, M. Yücel^a1a2 and C. Pantelis^a1

^a1 Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Melbourne Health, VIC, Australia

^a2 Orygen Research Centre, Melbourne, VIC, Australia

Abstract

Background Recent evidence from genetic and familial studies revitalized the debate concerning the validity of the distinction between schizophrenia and bipolar disorder. Comparing brain imaging findings is an important avenue to examine similarities and differences and, therefore, the validity of the distinction between these conditions. However, in contrast to bipolar disorder, most patient samples in studies of schizophrenia are predominantly male. This a limiting factor for comparing schizophrenia and bipolar disorder since male gender is associated with more severe neurodevelopmental abnormalities, negative symptoms and cognitive deficits in schizophrenia.

Method We used a coordinate-based meta-analysis technique to compare grey matter (GM) abnormalities in male-dominated schizophrenia, gender-balanced schizophrenia and bipolar disorder samples based on published voxel-based morphometry (VBM) studies. In total, 72 English-language, peer reviewed articles published prior to January 2011 were included. All reports used VBM for comparing schizophrenia or bipolar disorder with controls and reported whole-brain analyses in standard stereotactic space.

Results GM reductions were more extensive in male-dominated schizophrenia compared to gender-balanced bipolar disorder and schizophrenia. In gender-balanced samples, GM reductions were less severe. Compared to controls, GM reductions were restricted to dorsal anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex in schizophrenia and ACC and bilateral fronto-insular cortex in bipolar disorder.

Conclusions When gender is controlled, GM abnormalities in bipolar disorder and schizophrenia are mostly restricted to regions that have a role in emotional and cognitive aspects of salience respectively. Dorsomedial and dorsolateral prefrontal cortex were the only regions that showed greater GM reductions in schizophrenia compared to bipolar disorder.

(Received March 13 2011)

(Revised July 01 2011)

(Accepted July 06 2011)

(Online publication August 11 2011)

Key Words:

• Bipolar disorder;
• grey matter;
• MRI;
• schizophrenia;
• voxel based morphometry

Correspondence:

^c1 Address for correspondence: Dr E. Bora, Alan Gilbert Building NNF level 3, Carlton 3053, Australia. (Email: emrebora@hotmail.com)