A component analysis of action planning processes in schizophrenia: A comparison with patients with frontal lobe damage.

Introduction: One established line of research has suggested that frontal cortical dysfunction is involved in generating the pathophysiology underlying schizophrenia. Consequently it is predicted patients with schizophrenia will be impaired on tasks measuring executive functions. Methods: Using a set of multicomponent tasks that segregated various information processes used action planning, we assessed the ability to generate action knowledge and construct a plan of action in a group of 17 schizophrenic patients. The study consisted in two experiments: an action generation task and an action ordering task. Their performance was compared with those of a sample of 10 patients with frontal lobe lesions and of 16 normal control subjects. Results: Schizophrenic patients were significantly worse than normal subjects and frontal lobe patients in the semantic retrieval of action knowledge. Similar to frontal lobe lesions patients, they encountered difficulties in action sequencing and in setting priorities among the action events with regard to the stated goal. Interestingly, schizophrenic patients' impairment in organising a plan of action increased when distracters or novel situations were presented. Conclusions: Although the pattern of executive impairments observed in the schizophrenic patients are similar to those reported for patients with frontal lesions, the conditions under which the impairments occurred are different. The present study indicates that multiple functionally dissociable processes may contribute to action planning disorganisation in schizophrenia. [ABSTRACT FROM AUTHOR]