Abstract
IntroductionThe corpus callosum serves the essential role of relaying cognitive information between the homologous regions in the left and the right hemispheres of the brain. Cognitive impairment is a core dysfunction of schizophrenia, but much of its pathophysiology is unknown. The aim of this study was to elucidate the association between microstructural abnormalities of the corpus callosum and cognitive dysfunction in schizophrenia.MethodsWe examined stepwise multiple regression analysis to investigate the relationship of the fractional anisotropy (FA) of callosal fibers in each segment with z‐scores of each brief assessment of cognition in schizophrenia subtest and cognitive composite score in all subjects (19 patients with schizophrenia [SZ group] and 19 healthy controls [HC group]). Callosal fibers were separated into seven segments based on their cortical projection using tract‐specific analysis of diffusion tensor imaging.ResultsThe FA of callosal fibers in the temporal segment was significantly associated with z‐scores of token motor test, Tower of London test, and the composite score. In the SZ group, the FA of callosal fibers in the temporal segment was significantly associated with the z‐score of the Tower of London test. In addition, the FA of callosal fibers in temporal segment showed significant negative association with the positive and negative syndrome scale negative score in the SZ group. Compared to the HC group, the FA in temporal segment was significantly decreased in the SZ group.ConclusionOur results suggest that microstructural abnormalities in the callosal white matter fibers connecting bilateral temporal lobe cortices contribute to poor executive function and severe negative symptom in patients with schizophrenia.
Highlights
The corpus callosum serves the essential role of relaying cognitive information between the homologous regions in the left and the right hemispheres of the brain
In the SZ group, fractional anisotropy (FA) values of the corpus callosum (CC) that connects the bilateral temporal lobe cortices associated with executive function scores, and FA value of this tract was significantly decreased compared to the healthy controls (HC) group
These results indicate an association between microstructural abnormalities of the CC white matter and cognitive dysfunction in schizophrenia
Summary
The disconnection hypothesis in schizophrenia (Friston, 1999) is supported by repeated reports of abnormalities of white matter (WM) fibers that connect brain regions (Kubicki & Shenton, 2014; Samartzis, Dima, Fusar‐Poli, & Kyriakopoulos, 2014; Wheeler & Voineskos, 2014). The corpus callosum (CC), the largest commissural fiber bundle in the brain, connects the left and the right hemispheres and serves an essential role of relaying sensory, motor, and cognitive information between the homologous regions (Huang et al, 2005; Ribolsi, Daskalakis, Siracusano, & Koch, 2014). Cognitive impairment is a core dysfunction of schizophrenia that is associated with functional prognosis (Green & Harvey, 2014), but much of its pathophysiology is unknown. Few studies have performed detailed investigation of the relationship between microstructural abnormalities of CC and cognitive functioning in schizophrenia. We examined the association between microstructural abnormalities of CC fibers and cognitive dysfunction in schizophrenia by segmenting the CC fibers based on their cortical projection regions using DTI tract‐specific analysis (TSA). We hypothesized that patients with schizophrenia show microstructural abnormalities in CC fibers and these abnormalities are related to their cognitive impairment
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