Forty off-medication patients with schizophrenia will receive 18F2-deoxyglucose (2DG) while executing the Continuous Performance Task (CPT), a psychophysical attention assessment. Simultaneous 32-channel topographic evoked potentials (EPs) to CPT stimuli will be obtained. Following uptake of 2DG and labeling of brain structures in the psychophysiological laboratory, the Neuroecat Scanner will obtain slice images with 7.6-7.8 mm in plane and 11.6-12.2 axial resolution assess the metabolic rate of glucose. The 40 patients will be obtained from the Clinical Research Centers of UCLA. Sixteen patients will have adult onset of symptoms (age 18 or later) and sixteen will have childhood onset (age 10 or earlier) but will be currently age 15 or older. The patients will be prescreened for CPT performance and will be selected for extremely poor or good CPT performance. Eight additional adult patients with intermediate CPT scores will allow analysis of positive/negative subtypes. This provides a 2X2 cell design, adult/childhood onset, good/poor attention (n=8 in each of four cells) for within patient group contrasts. Four groups of 16 normal age-and sex-matched normal volunteers will serve as contrasts. The first will be additionally matched on CPT performance to the 16 good attention patients. The second will be naive to CPT instructions and will be asked only to use the stimuli as a fixation point. The third sample will have CPT task difficulty adjusted so that their performance matches the poor schizophrenics. The fourth will only press a button at 4 second intervals. PET images will be converted to units of micromoles glucose/100g/minute and analyzed quantitatively. Analyses will identify specific structures by reference to magnetic resonance scans. A second analysis will examine cortical surface activity obtained from our 3-D reconstruction technique and correlate this with regional evoked potential techniques. In our initial studies with PET, we found schizophrenics to have a diminished anteroposterior metabolic rate gradient with occipital and parietal areas showing higher rates than normal. The current study extends this work using PET with higher resolution, a cognitive task of widely demonstrated salience, topographic EPs covering both hemispheres, and NMR scans to identify anatomic landmarks with greater accuracy.
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