Physiological and behavioral correlates of attention dysfunction in schizophrenic patients

Abstract

SCHIZOPHRENIC patients usually perform poorer than normal subjects on most behavioral tasks. It is our contention that many of the behavioral deficits seen in the schizophrenic can be accounted for by a primary attentional disorder and/or a general lack of interest by the patient in playing the psychological games of the investigator. Much of the discordance in experiments with schizophrenic patients is probably due not only to the failure to obtain full participation of the patient, but also to failure to define adequately the study sample. Furthermore, experimental designs often suffer from the assumption that the disease state itself is a unitary function. Many investigators have attempted to subdivide their subject sample by subtype, i.e. paranoid versus non-paranoid, process versus reactive, good premorbid versus poor premorbid, etc; however, even this type of subdivision has often not given consistent results across a variety of experiments. In all of these studies the dividing of the schizophrenic sample into subtypes has been on the basis of some clinical characteristic of the patient and the dependent variable has been some performance measure. In the present report we will discuss a series of experiments in which we have used the opposite approach. The independent variable is the performance of the patients on a simple test of attention and the dependent variables are other performance tasks, various clinical subdivisions, and EEG recordings. The independent variable In previous work, we have found that the performance of approximately 40 % of chronic schizophrenics that we have tested on the Continuous Performance Test (CPT) is poorer than that of all normal subjects we have tested.1 We have interpreted this impairment as resulting from an attentional deficit. This attentional deficit has been found in schizophrenic patients who were in good remission and not on medication.2 Patients receiving antipsychotic medication are less likely to show an attentional deficit than patients not receiving such medication.lr3 The present paper will, for the most part, review those experiments in which we have compared schizophrenic patients with good performance on the CPT with those patients who do poorly on the CPT. The CPT consists of the presentation of stimuli, usually but not necessarily letters, in a random sequence at a constant rate and for a