NORMAL SUSTAINED EFFECTS OF SELECTIVE ATTENTION ARE ABSENT IN SCHIZOPHRENIC-PATIENTS WITHDRAWN FROM MEDICATION

Sustained attentional deficits have been widely reported in groups of medicated schizophrenic patients, but less is known about sequential a ttentional processes in patients withdrawn from medication. The attent ional performance of 12 medication-withdrawn schizophrenic outpatients was compared with that of 16 matched normal volunteers on a Stroop ne gative priming task. This task allowed examination of both within-tria l and between-trial attentional effects. Compared with the volunteers, the medication-withdrawn schizophrenic patients showed normal within- trial attentional effects as measured by standard Stroop interference and facilitation. Across trials, however, the schizophrenics exhibited reduced negative priming compared with the volunteers and in some cas es a complete reversal of sustained inhibitory processes. The findings suggest that a normal inhibitory tag occurred during initial selectio n in the patient group, but it did not influence a subsequent act of s election as was the case for the normal volunteers. Either inhibition decayed at an abnormally fast rate in the patient group or a separate facilatory tag dominated. In either case, priming effects linked to at tentional selection were clearly abnormal in the medication-withdrawn patient group.