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MRI white matter diffusion anisotropy and PET metabolic rate in schizophrenia
M S Buchsbaum1, C Y Tang, S Peled
1Department of Psychiatry, Neuroscience PET Laboratory, Mount Sinai Medical Center, New York, NY 10029-6574, USA.
Abstract:
A disturbance in the frontal-striatal-thalamic circuitry has been proposed for schizophrenia, but this concept has been based primarily on indirect evidence from psychopharmacology and analogies with animal research. Diffusion tensor imaging, a new MRI technique that permits direct assessment of the large axon masses stretching from the prefrontal cortex to the striatum, was used to study white matter axon bundles. Diffusion tensor images, high-resolution structural MRI and positron emission tomography scans with 18-fluorodexoyglucose were obtained on five patients with schizophrenia and six age- and sex-matched normal controls. Significantly lower diffusion anisotropy in the white matter of the prefrontal cortex in schizophrenic patients than in normal controls was observed in statistical probability maps. Co-registered PET scans revealed significantly lower correlation coefficients between metabolic rates in the prefrontal cortex and striatum in patients than in controls. These twin findings provide convergent evidence for diminished fronto-striatal connectivity in schizophrenia.
Insights
Schizophrenia may involve disrupted frontal-striatal brain connections. New MRI scans show reduced white matter integrity in the prefrontal cortex of patients, supporting this theory.
Area of Science:
- Neuroimaging
- Psychiatric Neuroscience
- Brain Connectivity
Background:
- Frontal-striatal-thalamic circuitry dysfunction is a proposed mechanism in schizophrenia.
- Previous evidence relied on indirect psychopharmacological and animal model data.
- Direct assessment of white matter tracts is needed.
Purpose of the Study:
- To directly investigate white matter integrity in the frontal-striatal pathway in schizophrenia.
- To examine the relationship between brain structure and metabolic activity in this circuitry.
Main Methods:
- Employed Diffusion Tensor Imaging (DTI) to assess white matter axon bundles.
- Utilized high-resolution structural MRI and 18-fluorodeoxyglucose Positron Emission Tomography (PET).
- Compared five schizophrenia patients with six healthy controls.
Main Results:
- Significantly lower diffusion anisotropy in the prefrontal cortex white matter of schizophrenia patients.
- Significantly lower correlation coefficients between prefrontal and striatal metabolic rates in patients.
- Convergent evidence for diminished fronto-striatal connectivity.
Conclusions:
- Findings provide direct evidence for impaired white matter connectivity in the frontal-striatal pathway in schizophrenia.
- Suggests structural and functional deficits contribute to the observed circuitry disturbance.