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Publications (5)39.66 Total impact

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    ABSTRACT: In an all-male sample of schizophrenic patients stabilized by medication (n=62) and normal controls (n=27), we obtained neuropsychological test data and high-resolution whole brain magnetic resonance scans, as well as detailed psychiatric rating scales on a subset of the patients (n=47). Schizophrenic patients had significantly worse overall age-adjusted cognitive performance than normal controls (average z-score=-0.90, range=-0.60 to -1.81), which included relatively more severe deficits with different types of memory, psychomotor speed, verbal fluency and verbal abstraction. Schizophrenic patients also had significantly smaller bilateral volumes in gray but not white matter in the prefrontal region, superior temporal gyrus and whole temporal lobe, but no group differences were observed in the hippocampus and parahippocampus. Correlations between the brain regions and cognitive performance revealed different sets of significant relationships for the two groups, particularly in the prefrontal and hippocampal regions. In addition, inverse correlations were observed between certain cognitive abilities (psychomotor speed, cognitive flexibility and verbal fluency) and patients' psychiatric ratings, especially with measures of negative symptoms. The convergence of findings for schizophrenic patients regarding the prefrontal region, negative symptoms, psychomotor speed and cognitive flexibility suggests that schizophrenic negative symptoms may involve disruption of frontal-subcortical connections.
    Psychiatry Research 12/2002; 116(1-2):1-23. · 2.68 Impact Factor
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    ABSTRACT: Previous research has provided evidence for brain abnormalities in schizophrenia, but their relationship to specific clinical symptoms and syndromes remains unclear. With an all-male demographically similar sample of 53 schizophrenic patients and 29 normal control subjects, cerebral gray and white matter volumes (adjusted for intracranial volume and age were determined for regions in the prefrontal lobe and in the superficial and mesial temporal lobe using T1-weighted magnetic resonance imaging with 2.8-mm coronal slices. As a group, schizophrenic patients had wide-spread bilateral decrements in gray matter in the pre-frontal (7.4%) and temporal lobe regions (8.9%), but not in white matter in these regions. In the temporal lobe, gray matter reductions were found bilaterally in the superior temporal gyrus (6.0%), but not in the hippocampus and parahippocampus. While there were no overall group differences in white matter volumes, widespread decrements in prefrontal white matter in schizophrenic patients (n = 53) were related to higher levels of negative symptoms (partial r[49] = -0.42, P = .002), as measured by the Scale for the Assessment of Negative Symptoms. A post hoc analysis revealed that schizophrenic patients with high negative symptoms had generalized prefrontal white matter reductions (11.4%) that were most severe in the orbitofrontal subregion (15.1%). These results suggest that gray matter deficits may be a fairly common structural abnormality of schizophrenia, whereas reductions in prefrontal white matter may be associated with schizophrenic negative symptoms.
    Archives of General Psychiatry 06/2000; 57(5):471-80. · 13.77 Impact Factor
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    ABSTRACT: We used traditional volumetric regional analysis and a finer anterior-posterior (AP) profile volumetric analysis to examine the cerebral ventricular system in an all-male, demographically matched sample of schizophrenia patients (n = 73) and normal controls (n = 29) using 2.8-mm-thin coronal T1-weighted magnetic resonance images from a 1.5 tesla scanner. Traditional regional analysis was performed on various regions using absolute volumes after adjusting for intracranial volume (ICV) and age. The fine AP profile analysis was done by intrasubject "stacking" of contiguous coronal cross-sectional volumes (adjusted for ICV and age) across the AP plane, intersubject AP alignment of all slices relative to the mammillary bodies, and plotting of slice volumes along the AP plane with 95 percent t-test-based confidence intervals. Schizophrenia subjects had mild to moderate multifocal ventricular enlargement (overall effect size d = 0.48), which was especially prominent in the right posterior temporal horn and, more generally, in the central to posterior portions of the lateral and third ventricles. Schizophrenia subjects also had milder enlargement in the left frontal horn, but no significant differences were found in the anterior temporal horns and the right frontal horn. Post hoc analyses of demographic, clinical, and neuropsychological variables did not account for much variance in the ventriculomegaly observed in the schizophrenia group. The lack of a single locus in the observed ventricular enlargement, the nonsignificant results from schizophrenia subtypes based on regional distributions, and the strong positive correlations among the ventricular regions for the schizophrenia group suggest that the ventriculomegaly seen in this chronic population reflects a single brainwide disease process leading to a multifocal or patchy loss of integrity in brain structure.
    Schizophrenia Bulletin 02/2000; 26(1):201-16. · 8.49 Impact Factor
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    ABSTRACT: Intersubject averaging of structural magnetic resonance (MR) images has been infrequently used as a means to study group differences in cerebral structure throughout the brain. In the present study, the authors used linear intersubject averaging of structural MR images to evaluate the validity and utility of this technique and to extend previous research, conducted using a different approach to image averaging, in which reduction in thalamic size and abnormalities in perithalamic white matter tracts in the brains of schizophrenic patients were reported by Andreasen et al. A 1.5-T MR scanner was used to obtain high-resolution, whole brain T1-weighted structural MR images for an age-matched sample of 25 schizophrenic patients and 25 normal control subjects. A "bounding box" procedure was used to create a single "averaged" brain for the schizophrenic group and for the control group. Differences in signal intensity between the two average brains were examined on a pixel-wise basis through use of one-tailed effect size maps. Effect size maps revealed widespread patchy signal intensity differences between the two groups in both cortical and periventricular areas, including major white matter tracts. The signal intensity differences were consistent with cortical thinning/sulcal widening and ventricular enlargement. No differences were found within thalamus or in immediately surrounding white matter. Effect size maps for differences (schizophrenic minus normal subjects) had only small values. These results are consistent with diffuse structural brain abnormalities of both gray and white matter in schizophrenic populations such as the one in this study.
    American Journal of Psychiatry 09/1998; 155(8):1064-73. · 14.72 Impact Factor
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    ABSTRACT: perior temporal gyrus (6.0%), but not in the hippocam- pus and parahippocampus. While there were no overall group differences in white matter volumes, widespread decrements in prefrontal white matter in schizophrenic patients (n = 53) were related to higher levels of nega- tive symptoms (partial r(49) = ˛0.42, P = .002), as mea- sured by the Scale for the Assessment of Negative Symp- toms. A post hoc analysis revealed that schizophrenic patients with high negative symptoms had generalized prefrontal white matter reductions (11.4%) that were most severe in the orbitofrontal subregion (15.1%). Conclusions: These results suggest that gray matter defi- cits may be a fairly common structural abnormality of schizophrenia, whereas reductions in prefrontal white matter may be associated with schizophrenic negative symptoms.