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This evaluation of seven high functioning adults with autism utilized positron emission tomography on a visual vigilance task. Although the subjects, as a group, did as well as normal controls on the task, there was a lack of normal hemispheric asymmetry in glucose metabolic rate. A heterogeneous etiology for autism is suggested to explain results. (DB)

There appear to be no brain imaging studies investigating which brain mechanisms subserve affective, impulsive violence versus planned, predatory violence. It was hypothesized that affectively violent offenders would have lower prefrontal activity, higher subcortical activity, and reduced prefrontal/subcortical ratios relative to controls, while predatory violent offenders would show relatively normal brain functioning. Glucose metabolism was assessed using positron emission tomography in 41 comparisons, 15 predatory murderers, and nine affective murderers in left and right hemisphere prefrontal (medial and lateral) and subcortical (amygdala, midbrain, hippocampus, and thalamus) regions. Affective murderers relative to comparisons had lower left and right prefrontal functioning, higher right hemisphere subcortical functioning, and lower right hemisphere prefrontal/subcortical ratios. In contrast, predatory murderers had prefrontal functioning that was more equivalent to comparisons, while also having excessively high right subcortical activity. Results support the hypothesis that emotional, unplanned impulsive murderers are less able to regulate and control aggressive impulses generated from subcortical structures due to deficient prefrontal regulation. It is hypothesized that excessive subcortical activity predisposes to aggressive behaviour, but that while predatory murderers have sufficiently good prefrontal functioning to regulate these aggressive impulses, the affective murderers lack such prefrontal control over emotion regulation. [ABSTRACT FROM AUTHOR]

Local cerebral uptake of glucose labelled with fluorine-18 was measured by positron emission tomography in 13 patients with schizophrenia and 37 right-handed volunteers. Patients received no medication for a minimum of 31 days and a mean of 30 weeks. The subjects were administered the labelled deoxyglucose just after the beginning of a 32-minute sequence of blurred numbers as visual stimuli for the Continuous Performance Test. In normal controls, task performance was associated with increases in glucose metabolic rate in the right frontal and right temporoparietal regions; occipital rates were unchanged. Patients with schizophrenia showed both absolutely and relatively reduced metabolic rates in the frontal cortex and in the temporoparietal regions compared with normal controls. [ABSTRACT FROM AUTHOR]

Individuals potentially at risk for psychiatric disorders were identified by screening 375 college student volunteers for low platelet monoamine oxidase (MAO) activity levels. The lower and upper 10% in MAO activity were administered a personal and family history interview, psychological tests and average evoked response (AER) electroencephalographic procedures. Results indicated that low MAO males and females were socially more active, had more psychiatric contact, and had relatives who were psychiatrically more disturbed than high MAO subjects. Low MAO males had more convictions, experimented more with illegal drugs and had elevated scores on the MMPI. AER criteria further defined a high risk group of low MAO-AER augmenters which had more suicides among their relatives and higher scores on the schizophrenia scale of the MMPI. [ABSTRACT FROM AUTHOR]