Normal sustained effects of selective attention are absent in schizophrenic patients withdrawn from medication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in groups of medicated schizophrenic patients, but less is known about sequential attentional processes in patients withdrawn from medication. The attentional performance of 12 medication-withdrawn schizophrenic outpatients was compared with that of 16 matched normal volunteers on a Stroop negative priming task. This task allowed examination of both within-trial 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 Compared with the volunteers, the medication-withdrawn schizophrenic patients showed normal within-trial attentional effects as measured by standard Stroop interference and facilitation.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 cases a complete reversal of sustained inhibitory processes. The findings suggest that a normal inhibitory tag occurred during initial selection in the patient group, but it did not influence a subsequent act of selection 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 In either case, priming effects linked to attentional selection were clearly abnormal in the medication-withdrawn patient group.