Spatial low frequency pattern analysis in positron emission tomography: a study between normals and schizophrenics.

Using the two-dimensional Fourier transform and the brain's centroidal principal axis, a method is developed for the analysis of PET metabolic brain images without the use of predefined anatomic regions of interest. We applied the method to images from a group of 11 normal and 12 medicated schizophrenics tested under resting conditions and under a visual task. A cortical/subcortical spatial pattern was found to be significant in two directions; anterior/posterior and chiasmatic (left-anterior/right-posterior).

Multivariate analyses of the EEG in normal adolescents.

We investigated the computerized electroencephalography (cEEG) in a group of 85 normal adolescents. The spatial frequency of the cEEG was analyzed using various multivariate statistical techniques. The factor analyses revealed three factors that accounted for most of the variability in the data and that could be interpreted as a low versus high frequency, a beta frequency, and a frontal versus posterior factor.

Phenomenological correlates of metabolic activity in 18 patients with chronic schizophrenia.

Using [11C]-deoxy-D-glucose and positron emission tomography (PET), the authors measured brain metabolism in 18 patients with chronic schizophrenia to assess which of the metabolic measures from two test conditions was more closely related to the patients' differing clinical characteristics. The two conditions were resting and activation, and an eye tracking task was used. Patients with more negative symptoms showed lower global metabolic rates and more severe hypofrontality than did the patients with fewer negative symptoms.

Brain organization in schizophrenia.

Brain metabolism was measured with positron emission tomography and [11C]deoxyglucose during baseline and during a visual task in 12 normal subjects and 18 schizophrenic patients. Global measures of metabolism for 11 brain regions were transformed into relative values by dividing them by the metabolic value for whole brain. Factor analysis was accomplished on the matrix of intercorrelations among the relative regional values for the normal and for the schizophrenic patients under baseline and under the task.

Persistence of cerebral metabolic abnormalities in chronic schizophrenia as determined by positron emission tomography.

Local cerebral metabolic rates were determined by positron emission tomography and the deoxyglucose method in a group of 10 chronic schizophrenic subjects before and after somatic treatment and in eight normal subjects. Before treatment, schizophrenic subjects had markedly lower absolute metabolic activity than did normal controls in both frontal and temporal regions and a trend toward relative hyperactivity in the basal ganglia area. After treatment, their metabolic rates approached those seen in normal subjects in nearly all regions except frontal.

Patterns of metabolic activity in the treatment of schizophrenia.

Six patients with chronic schizophrenia were studied with positron emission tomography (PET) before and after neuroleptic treatment, using fluorine-18-labeled fluorodeoxyglucose. After treatment, the mean whole-slice glucose metabolic rate at the level of the basal ganglia showed a 25% increase. However, patterns of frontal hypometabolism observed with the schizophrenic patients were not altered by medication.

Validity and reliability of a high school drug use questionnaire among Mexican students.

This study was carried out to ascertain the validity and reliability of data generated through an internationally developed self-administered questionnaire. Data were collected from two student populations in which prevalence of drug use was known (high and low prevalence rates) and information obtained from the questionnaire checked through personal interview. The questionnaire covered both demographic characteristics and drug use items.