Mild procedural learning disturbances in neuroleptic-naive patients with schizophrenia.

This study investigated whether drug-naive patients with schizophrenia present procedural learning disturbances, given that this function is known to involve the striatum and that structural abnormalities of the striatum have been described in these patients. Eleven neuroleptic-free schizophrenic patients were compared with 11 healthy control subjects on a visuomotor procedural learning task (the Mirror Drawing Test). Average performance and learning rate did not differ between the two groups. However, schizophrenia patients were lower in learning smoothness (the consistency with which performance improves from trial to trial), which would indicate difficulty in benefiting from past experience to perform better on a current task. Because low smoothness has recently been found to be associated with striatal dysfunction, these results might indicate a premature dysfunction of the striatum in young drug-naive patients with schizophrenia. However, this dysfunction is not severe enough to prevent learning.