DIFFERENTIAL-EFFECTS OF D-2-BLOCKING AND D-4-BLOCKING NEUROLEPTICS ONTHE PROCEDURAL LEARNING OF SCHIZOPHRENIC-PATIENTS

Objective: To illustrate the differential effects of D-2- and D-4-bloc king neuroleptics on the procedural (earning of patients with schizoph renia. Method: Twenty-nine schizophrenic patients were divided into 3 groups according to their pharmacological treatment: 1) drug naive, 2) haloperidol, and 3) clozapine. They were all assessed on clinical and procedural measures. the latter being the mirror drawing task. Result s: All groups showed progressive learning over the successive trials, and drug-naive patients performed better than the other groups. Patien ts in the haloperidol group showed many fluctuations over trials, sugg esting difficulty in the progressive automation of the task. Such fluc tuations did not occur in the clozapine group, but performances per se were worse than in the other groups during the learning trials. Autom ation of the task occurred at the same point (second block of trials) for all groups. Conclusion: These results suggest that D-2- and D-4-bl ocking neuroleptics do not similarly affect striatal dependent procedu ral learning in schizophrenia.