MedWire News: Individuals at high genetic risk for schizophrenia exhibit structural abnormalities in brain regions associated with language processing, research shows.
"Structural and functional brain deficits throughout the cerebral cortex, particularly in the language-processing associated brain regions, are consistently reported [in patients with schizophrenia]," observe Xiaobo Li (Yeshiva University, New York, USA) and team.
"Recently, increasing evidence from magnetic resonance imaging (MRI) studies suggests that healthy relatives of schizophrenia patients also show structural brain abnormalities in cortical gray matter (GM) volume and thickness, suggesting that this may be associated with an unexpressed genetic liability for the disorder," they add.
To investigate further, the researchers studied 20 schizophrenia patients (mean age 37.7 years), 21 non-psychotic participants (mean age 21.1 years) at increased genetic risk for schizophrenia, and 48 mentally healthy controls. The researchers note that the high-risk participants were all at the peak age of schizophrenia development.
All of the participants underwent MRI brain scans and structural data in 14 bilateral regions of interest (ROIs) associated with language processing.
The researchers found that schizophrenia patients exhibited a significant global decrease in gray matter density compared with high-risk individuals and controls, as well as significant global decreases in cortical thickness and area.
Compared with controls, high-risk individuals exhibited increased regional cortical thickness in seven ROIs, as well as increased gray matter density in scattered regions associated with language processing.
Spatial distribution of abnormal cortical thickness in the schizophrenia patients and high-risk individuals contributed to a decrease in "normal" anatomical asymmetry in the inferior orbital frontal area, and an increase in asymmetry in the inferior parietal and occipital regions.
"The results of the present study suggest that developmental disruption of the anatomical differentiation of the hemispheres provides a basis for understanding the language impairment and symptoms of psychosis, and that these may arise because of abnormal left-right hemispherical communications that interrupt the normal flow of information processing," comment Li and team in Psychiatry Research: Neuroimaging.
They conclude: "The early structural deficits in language-processing circuits may precede the appearance of psychotic symptoms and may be an indicator of an increased risk of developing schizophrenia."
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