Cingulum bundle abnormalities and risk for schizophrenia

Background: The cingulum bundle (CB) is a major white matter fiber tract of the limbic system that underlies cingulate cortex, passing longitudinally over the corpus callosum. The connectivity of this white matter fiber tract plays a major role in emotional expression, attention, motivation, and working memory, all of which are affected in schizophrenia. Myelin related CB abnormalities have also been implicated in schizophrenia. The purpose of this study is to determine whether or not CB abnormalities are evident in individuals at clinical high risk (CHR) for psychosis, and whether or not cognitive deficits in the domains subserved by CB are related to its structural abnormalities. Methods: Diffusion Tensor Imaging (DTI) was performed on a 3 T magnet. DT tractography was used to evaluate CB in 20 individuals meeting CHR criteria (13 males/7 females) and 23 healthy controls (12 males/11 females) group matched on age, gender, parental socioeconomic status, education, and handedness. Fractional anisotropy (FA), a measure of white matter coherence and integrity, radial diffusivity (RD), thought to reflect myelin integrity, trace, a possible marker of atrophy, and axial diffusivity (AD), thought to reflect axonal integrity, were averaged over the entire tract and used to investigate CB abnormalities in individuals at CHR for psychosis compared with healthy controls. Results: Significant group differences were found between individuals at CHR for psychosis and controls for FA (p = 0.028), RD (p = 0.03) and trace (p = 0.031), but not for AD (p = 0.09). We did not find any significant correlations between DTI measures and clinical symptoms. Conclusion: These findings suggest abnormalities (possibly myelin related) in the CB in individuals at CHR for psychosis. (C) 2019 Elsevier B.V. All rights reserved.