GLUCOSE METABOLIC CORRELATES OF CONTINUOUS PERFORMANCE-TEST PERFORMANCE IN ADULTS WITH A HISTORY OF INFANTILE-AUTISM, SCHIZOPHRENICS, AND CONTROLS

Twenty-five schizophrenic patients, fourteen adults with a history of infantile autism, and twenty normal controls performed a test of susta ined attention, the degraded stimulus continuous performance test (CPT ), during the 35 minute 18-fluoro-2-deoxyglucose uptake period precedi ng positron emission tomographic (PET) scan acquisition. This is the f irst analysis comparing correlations between glucose metabolic rate (G MR) for selected regions and CPT performance. CPT performance differed in controls and schizophrenics, but autistics did not differ from eit her group. In controls and schizophrenic patients, task performance co rrelated with GMR in medial superior frontal gyrus and lateral inferio r temporal gyrus, suggesting that activation of those regions is impor tant in the normal performance of the task and that damage to those re gions, which also showed low GMR in schizophrenics, contributes to the attentional dysfunction in schizophrenia. Also, schizophrenics showed negative correlations of task performance with anterior cingulate act ivity suggesting that overactivity of that region, which is involved i n mental effort and whose GMR was low in our larger study of schizophr enia, impairs task performance in schizophrenics. Autistic patients sh owed negative correlations of medial frontal cortical GMR with attenti onal performance, suggesting that neuronal inefficiency in that region may contribute to poor performance.