Neuroleptics improve sustained attention in schizophrenia. A study using signal detection theory

To test the hypothesis that antipsychotic drugs improve attentional processes in schizophrenia, we used a computer-controlled, perceptually degraded continuous performance test (CPT), based on signal detection theory. CPT stimuli were degraded (blurred) to reduce discriminability so that signal detection analysis could be used to distinguish specific attentional processes, as measured by A', from nonspecific factors, as measured by B". Thirteen medicated and 12 neuroleptic-withdrawn schizophrenics visually monitored digits to detect a target under perceptually undegraded and degraded conditions. The principal result was that the neuroleptic-withdrawn patients showed a significant decline in the attention-specific measure of A' over time on task only for the degraded targets, independent of changes in the nonspecific index of B". These results demonstrate that neuroleptic withdrawal may compromise specific attentional processes, namely the ability to sustain attention, as measured by a precise performance task which controlled for nonspecific factors.