Single-photon emission computed tomography (SPECT) imaging with n-isopropyliodoamphetamine (IMP) was performed on 11 patients with bipolar mania, 21 acute schizophrenics, and 15 healthy control subjects. Subjects were evaluated with neuropsychological tests and psychiatric rating scales. SPECT brain studies were blindly evaluated to assess the degree of radiopharmaceutical uptake in three neuroanatomical regions of interest in each hemisphere. All the control subjects, 1 manic patient, and 1 schizophrenic patient had normal brain SPECT uptake patterns. The scans of all others were read as abnormal. Hypofrontality was noted in some schizophrenics and maniacs. A significant increase in tracer uptake in temporal lobes was observed in both patient groups, more prominently in the manic patients. Increased and decreased basal ganglia uptake was also observed in patients. Both manic and schizophrenic patients showed cortical tracer heterogeneity of varying degree. The patterns of cerebral SPECT uptake seen in these acute psychoses were not specific for a diagnosis, but may be associated with dimensions of psychopathology. Because the patterns are different from those seen in cerebrovascular disease and the dementias, they may prove to be helpful in differential diagnosis.

To determine the specificity of suggested endophenotypes of pediatric bipolar disorder (PBD), the performance of 15 euthymic children with PBD was contrasted with that of 20 children with attention-deficit/hyperactivity disorder (ADHD), a population with reportedly similar executive dysfunction, and 18 children with both PBD and ADHD. Children with PBD and PBD+ADHD (ages 8 to 17) demonstrated higher intraindividual variability in reaction time, slower processing speed, and more sluggish motor preparedness than did children with ADHD. The findings support the contention that processing speed, intraindividual variability, and slower and more variable reaction time as interstimulus interval lengthens are likely specific endophenotypes of PBD.

Although computed tomography (CT) and magnetic resonance imaging scans often appear normal after mild head trauma, many patients experience attentional or other cognitive disturbances that are difficult to quantify by neuropsychological testing in the absence of a premorbid profile. Within 2 days of mild head trauma, 14 patients with normal-appearing brain CTs were studied with single-photon emission computed tomography (SPECT). They were compared to 15 normal control subjects and to 12 patients with mild human immunodeficiency virus (HIV) encephalopathy. Ten of 14 head trauma patients were separated from the normal control subjects by both independent readers, blinded to the clinical diagnosis. None of the SPECT results from normal control subjects were "read" as trauma. Trauma could not be differentiated from HIV encephalopathy. The observed percentage agreement between raters was 0.83 (kappa = 0.72). SPECT is more sensitive than CT in detecting brain injury after mild head trauma.

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