Macroscopic brain asymmetry is changed along the antero-posterior axis in schizophrenia

Anatomical asymmetry may be altered in schizophrenia, but the changes are subtle and in some studies undetected perhaps due to methodological limitations.

In a postmortem MRI study (23 patients, 20 controls), we used a geometric mesh technique to define the cortical surface and to separate two components of brain asymmetry: hemisphere shift, conceived as the position of an entire hemisphere relative to the other (which may be reversed in situs inversus), and the distribution of tissue within the hemisphere along the antero-posterior axis ("volume torque").

Only volume torque was changed in schizophrenia-in comparison subjects, the coronal section of maximal left hemisphere volume was more anteriorly placed than on the right [and correlated with left superior temporal gyrus (STG) volume], and, in patients, it was more posterior (showing a reversed correlation with left STG volume).

The findings validate a new approach to cerebral asymmetry. Assessments of cerebral asymmetry in psychosis should account for, or exclude, hemisphere shift, which is not changed, and focus on the second component, A-P volume distribution; the findings point to an anomaly of relative hemispheric development that may have pathophysiological significance.