Investigation of corpus callosum in schizophrenia with diffusion imaging

Corpus callosum (CC) is the main white matter commissure between the two cerebral hemispheres. Abnormalities of CC have been shown in schizophrenia patients by magnetic resonance imaging (MRI) studies. We here further investigated CC organization with diffusion imaging (DWI) in a sample of schizophrenia patients recruited from the epidemiologically defined catchment area of South Verona, Italy.

Sixty-seven patients with schizophrenia and 70 normal controls were studied. Regions of interests (ROIs), standardized at 5 pixels, were placed in CC on the non-diffusion weighted echoplanar images (b = 0) and were then automatically transferred to the corresponding maps to obtain the apparent diffusion coefficient (ADC) of water molecules.

ADC measures for all callosal subregions in schizophrenia patients were significantly greater compared to normal controls (ANCOVA, p < 0.05). Positive symptoms significantly correlated with anterior callosal ADC measures (partial correlation analyses, p < 0.05).

These findings support the existence of widespread microstructure disruption of CC in schizophrenia, which may ultimately lead to inter-hemispheric misconnection, and also suggest a specific role of anterior transcallosal disconnectivity in underlying positive symptoms. Future longitudinal MRI studies in high risk and first-episode patients together with neurophysiological tests are indicated to further examine CC anatomical abnormalities and inter-hemispheric transmission in schizophrenia.