Abnormal angular gyrus asymmetry in schizophrenia.

OBJECTIVE: Few studies have evaluated the parietal lobe in schizophrenia despite the fact that it has an important role in attention, memory, and language-all functions that have been reported to be abnormal in schizophrenia. The inferior parietal lobule, in particular, is of interest because it is not only part of the heteromodal association cortex but also is part of the semantic-lexical network, which also includes the planum temporale. Both the inferior parietal lobule, particularly the angular gyrus of the inferior parietal lobule, and the planum temporale are brain regions that play a critical role as biological substrates of language and thought. The authors compared volume and asymmetry measures of the individual gyri of the parietal lobe by means of magnetic resonance imaging (MRI) scans. METHOD: MRI scans with a 1. 5-Tesla magnet were obtained from 15 male chronic schizophrenic and 15 comparison subjects matched for age, gender, and parental socioeconomic status. RESULTS: Inferior parietal lobule volumes showed a leftward asymmetry (left 7.0% larger than right) in comparison subjects and a reversed asymmetry (left 6.3% smaller than right) in schizophrenic subjects. The angular gyrus accounted for this difference in asymmetry, with the left angular gyrus being significantly larger (18.7%) than the right in comparison subjects, a finding that was not observed in schizophrenic patients. A further test of angular gyrus asymmetry showed a reversal of the normal left-greater-than-right asymmetry in the schizophrenic patients. CONCLUSIONS: Patients with schizophrenia showed a reversed asymmetry in the inferior parietal lobule that was localized to the angular gyrus, a structure belonging to the heteromodal association cortex as well as being part of the semantic-lexical network. This finding contributes to a more comprehensive understanding of the neural substrates of language and thought disorder in schizophrenia.

Superior temporal gyrus volume abnormalities and thought disorder in left-handed schizophrenic men.

OBJECTIVE: Studies of schizophrenia have not clearly defined handedness as a differentiating variable. Moreover, the relationship between thought disorder and anatomical anomalies has not been studied extensively in left-handed schizophrenic men. The twofold purpose of this study was to investigate gray matter volumes in the superior temporal gyrus of the temporal lobe (left and right hemispheres) in left-handed schizophrenic men and left-handed comparison men, in order to determine whether thought disorder in the left-handed schizophrenic men correlated with tissue volume abnormalities. METHOD: Left-handed male patients (N = 8) with DSM-III-R diagnoses of schizophrenia were compared with left-handed comparison men (N = 10) matched for age, socioeconomic status, and IQ. Magnetic resonance imaging (MRI) with a 1.5-T magnet was used to obtain scans, which consisted of contiguous 1.5-mm slices of the whole brain. MRI analyses (as previously defined by the authors) included the anterior, posterior, and total superior temporal gyrus in both the left and right hemispheres. RESULTS: There were three significant findings regarding the left-handed schizophrenic men: 1) bilaterally smaller gray matter volumes in the posterior superior temporal gyrus (16% smaller on the right, 15% smaller on the left); 2) a smaller volume on the right side of the total superior temporal gyrus; and 3) a positive correlation between thought disorder and tissue volume in the right anterior superior temporal gyrus. CONCLUSIONS: These results suggest that expression of brain pathology differs between left-handed and right-handed schizophrenic men and that the pathology is related to cognitive disturbance.

Quantitative volumetric MRI study of the cerebellum and vermis in schizophrenia: clinical and cognitive correlates.

OBJECTIVE: Recent evidence suggests that the cerebellum may play a role in higher cognitive functions and, therefore, may play an important role in schizophrenia. METHOD: The authors used magnetic resonance imaging to measure cerebellum and vermis volume in 15 patients with schizophrenia and 15 normal comparison subjects. RESULTS: They found that 1) vermis volume was greater in patients with schizophrenia than in normal subjects, 2) greater vermis white matter volume in the patients with schizophrenia significantly correlated with severity of positive symptoms and thought disorder and with impairment in verbal logical memory, and 3) patients with schizophrenia showed a trend for more cerebellar hemispheric volume asymmetry (left greater than right). CONCLUSIONS: These data suggest that an abnormality in the vermis may contribute to the pathophysiology of schizophrenia.

Volumetric evaluation of the thalamus in schizophrenic male patients using magnetic resonance imaging.

BACKGROUND: The thalamus, an important subcortical brain region connecting limbic and prefrontal cortices, has a significant role in sensory and cortical processing. Although inconsistently, previous studies have demonstrated neuroanatomical abnormalities in the thalamus of schizophrenic patients. METHODS: This structural magnetic resonance imaging study, based on segmentation of contiguous coronal 1.5-mm images, compared thalamic brain volumes of 15 chronic, male schizophrenic patients with 15 normal controls matched on age, sex, handedness, and parental socioeconomic status. RESULTS: There were no significant differences between patients and controls in thalamic volumes, right or left, adjusted for total brain volume; however, there were significantly different correlations of thalamic volumes with prefrontal white matter and lateral ventricles among patients, but not among controls. Thalamic volumes among patients were also significantly correlated with bizarre behavior, hallucinations, and thought disorder. CONCLUSIONS: Findings suggest that connectivity between thalamic nuclei and prefrontal cortical areas are abnormal in chronic male schizophrenic patients. In addition, ventricular enlargement may be, in part, due to subtle reduction in thalamic volume and/or in volume of thalamocortical and corticothalamic fibers secondary to thalamic abnormalities. Finally, correlations with positive symptomatology underscore the role of the thalamus in gating or filtering of sensory information and coordination of cortical processing.