Differential effects of D2- and D4-blocking neuroleptics on the procedural learning of schizophrenic patients.
OBJECTIVE
To illustrate the differential effects of D2- and D4-blocking neuroleptics on the procedural learning of patients with schizophrenia.


METHODS
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.


RESULTS
All groups showed progressive learning over the successive trials, and drug-naive patients performed better than the other groups. Patients in the haloperidol group showed many fluctuations over trials, suggesting difficulty in the progressive automation of the task. Such fluctuations did not occur in the clozapine group, but performances per se were worse than in the other groups during the learning trials. Automation of the task occurred at the same point (second block of trials) for all groups.


CONCLUSIONS
These results suggest that D2- and D4-blocking neuroleptics do not similarly affect striatal dependent procedural learning in schizophrenia.
Bédard
M A
MA
Université du Québec à Montréal (UQAM).
Scherer
H
H
Delorimier
J
J
Stip
E
E
Lalonde
P
P
D000328:Adult; D014150:Antipsychotic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D003024:Clozapine / Q000009:adverse effects / Q000627:therapeutic use*; D004193:Discrimination Learning / Q000187:drug effects; D065127:Dopamine D2 Receptor Antagonists; D005260:Female; D006220:Haloperidol / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D011939:Mental Recall / Q000187:drug effects* / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D009949:Orientation / Q000187:drug effects; D010364:Pattern Recognition, Visual / Q000187:drug effects*; D011340:Problem Solving / Q000187:drug effects*; D011597:Psychomotor Performance / Q000187:drug effects*; D017448:Receptors, Dopamine D2 / Q000502:physiology; D050638:Receptors, Dopamine D4; D012559:Schizophrenia / Q000188:drug therapy* / Q000503:physiopathology
D014150:Antipsychotic Agents; C493599:DRD4 protein, human; D065127:Dopamine D2 Receptor Antagonists; D017448:Receptors, Dopamine D2; D050638:Receptors, Dopamine D4; D003024:Clozapine; D006220:Haloperidol