Assessment of differential attention mechanisms in seizure disorders and schizophrenia.

This study examines differential attention deficits in 19 temporal lobe epilepsy (TLE) patients, 15 generalized seizure patients (GSP), and 19 schizophrenic patients, compared to 20 normal controls. All participants were tested on a variable foreperiod reaction time (RT) task and continuous performance test (CPT). Temporal lobe epilepsy patients and schizophrenic patients show crossover deficits on the RT task requiring a conscious, effortful, preparatory motor set; while GSP show impairments on the CPT requiring vigilant, self-directed attention to external stimuli. The results suggest separate cortical and subcortical brain systems in the respective attentional deficits and in the etiologies of TLE, GSP, and schizophrenic disorders.

Effects of age, neuropsychological impairment, and medication on regional cerebral blood flow in schizophrenia and major affective disorder.

Reports of abnormalities of regional cerebral blood flow (rCBF) in patients with schizophrenia and major affective disorder are contradictory. To gain a better understanding of the possible sources of these contradictions, the rCBF and neuropsychological functioning of 15 schizophrenics, 15 patients with major affective disorder, and 15 age-matched controls were studied. No group differences in overall rCBF, percent frontal deviation in flow, or rCBF asymmetries were observed. Both overall rCBF and percent frontal deviation of rCBF were reduced with greater age and with increasing neuropsychological impairment. Dosage of neuroleptic medication was associated with reduced whole brain flow, not with percent frontal deviation flow. Previously reported differences in the resting rCBF of schizophrenics might be more closely related to the age of the subjects and to their neuropsychological impairment rather than the inherent progression of the disorder.