Myelination deficits in schizophrenia: evidence from diffusion tensor imaging.
BACKGROUND
Diffusion Tensor Imaging studies have repeatedly shown a decrease of the fractional anisotropy (FA) parameter in patients with schizophrenia. This has been interpreted as a disturbed microstructural integrity of white matter. However, FA is a relative parameter that is derived from eigenvalues of the diffusion tensor and FA reductions may be the result of decreases in parallel diffusivity (PD) or increases in radial diffusivity (RD). Despite the well-established FA reduction in schizophrenia, little is known what this reduction is based on.


METHODS
Seventeen patients with schizophrenia were scanned with a DTI protocol and compared to a group of healthy control subjects. In addition to an FA comparison, a detailed analysis of PD and RD values was performed with two approaches to localize changes in diffusion values, i.e. a voxel-based analysis and an anatomically based tract specific analysis.


RESULTS
We found significantly decreased FA values in the patient group when compared to healthy controls. FA decreases were based on an increase in RD, while we observed no significant changes of PD. These changes were predominantly localized in frontal and temporal areas.


CONCLUSIONS
RD increases as the underlying change in FA decreases is suggestive of desintegration of myelin, which is in line with histopathological studies suggesting a disturbed myelination in schizophrenia.
Department of Neuroradiology, Charité, Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany. michael.scheel@charite.de
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M
Scheel
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Prokscha
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Bayerl
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Gallinat
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Montag
D000328:Adult; D016880:Anisotropy; D016022:Case-Control Studies; D003711:Demyelinating Diseases / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D005260:Female; D005625:Frontal Lobe / Q000473:pathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D056347:Neuroanatomical Tract-Tracing Techniques; D012559:Schizophrenia / Q000473:pathology*; D013702:Temporal Lobe / Q000473:pathology*; D055815:Young Adult