Neuroanatomical abnormalities in schizophrenia elucidated
MedWire News: Results from a systematic review and meta-analysis of published studies show that schizophrenia is characterized by significant gray matter (GM) and white matter (WM) abnormalities, which often overlap and are associated with illness chronicity.
"Structural magnetic resonance imaging studies of schizophrenia have revealed gray and white matter abnormalities in several neural networks including fronto-striatal, fronto-temporal and anterior limbic connections," explain Emre Bora (University of Melbourne, Victoria, Australia) and team.
They add: "Most of these studies used a region of interest (ROI) approach and provided evidence for structural abnormalities in some components of these networks (ie, hippocampus, thalamus, and medial frontal regions).
"However, one important limitation of ROI studies is that they typically focus on one or a few specific structures (eg, hippocampus), neglecting the majority of brain areas."
To examine the evidence for GM and WM abnormalities in schizophrenia, and to assess the influence of gender, chronicity, negative symptoms and other clinical variables, the team searched the literature for relevant studies published between 2000 and 2010.
In total, 79 studies involving 3601 patients with schizophrenia and 3795 individuals without the condition (controls) met criteria for inclusion in the final meta-analysis.
Examination of the pooled data revealed that, compared with controls, schizophrenia patients had significant GM reductions in the bilateral insula/inferior frontal cortex, superior temporal gyrus, anterior cingulate gyrus/medial frontal cortex, thalamus, and left amygdala.
Regarding WM, schizophrenia patients showed reduced fractional anisotropy and/or WM volume in interhemispheric fibers, anterior thalamic radiation, inferior longitudinal fasciculi, inferior frontal occipital fasciculi, cingulum, and fornix.
Further analysis showed that male gender, increased illness chronicity, and increased negative symptoms were positively associated with more severe GM abnormalities, while increased illness chronicity was positively associated with increased WM deficits.
Bora and team conclude: "The meta-analyses revealed overlapping GM and WM structural findings in schizophrenia, characterized by bilateral anterior cortical, limbic and subcortical GM abnormalities, and WM changes in regions including tracts that connect these structures within and between hemispheres."
They add: "Longitudinal studies examining GM and WM simultaneously in patients with schizophrenia at multiple time points before and after the onset of psychosis will be valuable to further understand the nature of structural abnormalities in schizophrenia."
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By Mark Cowen