Microstructural alterations of the corpus callosum in affective and non-affective early psychosis: A diffusion magnetic resonance imaging study

Background

Early psychosis (EP) is associated with a disrupted integrity of the white matter microstructure of a variety of brain regions, especially the corpus callosum (CC). In this study, we used diffusion-weighted magnetic resonance imaging data of patients with EP and employed diffusion tensor imaging (DTI), free water-corrected diffusion, and neurite orientation dispersion and density imaging (NODDI) to comprehensively assess the white matter microstructure.

Methods

106 patients with EP (84 non-affective and 22 affective) and 51 healthy controls (HCs) were included from the Human Connectome Project in the Early Psychosis dataset. We used tract-specific analysis for tractography of three parts of the CC and quantified the diffusion measurements for each segment. CC measurement differences between EP vs. HCs and affective vs. non-affective psychosis were assessed by multivariate analysis of covariance. Principal component analysis was used for dimension reduction of diffusion metrics.

Results

EP was associated with disrupted white matter integrity in the body of CC indicated by a lower fractional anisotropy and intracellular volume fraction, alongside increased diffusivity measures. None of the CC subregions showed a significant difference in the genu and splenium of the CC between EP and HC groups or between affective and non-affective subgroups. Furthermore, lower white matter integrity in the genu was marginally associated with increased symptom severity.

Conclusions

Our findings suggest that microstructural alterations of white matter fibers crossing CC may underlie the pathophysiology of EP. These findings may contribute to a growing body of evidence pointing to white matter disruption as a potential biomarker of disease vulnerability.