INITIATION AND SUPERVISORY PROCESSES IN SCHIZOPHRENIA AND DEPRESSION

Clinical studies show that schizophrenic and depressive subjects have problems with daily life activities, and neuropsychological studies te nd to explain these problems in terms of a dysexecutive syndrome. Verb al fluency and sentence arrangement are tasks considered to focus on t wo aspects of the dysexecutive syndrome known as initiation and superv ision processes, respectively. In this study, we assessed performance in these two tasks in schizophrenia and depression. Twenty-six schizop hrenic subjects (chronic schizophrenia, DSM IV definition) were compar ed with 26 control subjects balanced for sex, age and educational leve l, and 16 depressive subjects (major depression episode, DSM IV) were compared with 11 similarly balanced control subjects. Switching and cl ustering scores were evaluated during a semantic fluency task as two c omponents underlying the initiation and organization processes. Captur e errors specific to failure of the supervisory system and differences between the number of correct responses in two conditions (valid/inva lid) were evaluated as indexes of the supervision process in a sentenc e arrangement task. In the semantic fluency task, switching scores wer e significantly lower in the schizophrenic and depressive subjects tha n in their respective controls. In the sentence arrangement task, only the schizophrenic subjects made significantly more capture errors tha n their controls and had significantly fewer correct sequences in inva lid conditions than in valid conditions. This study shows a dissociati on between supervision and initiation processes in two different psych iatric populations. Initiation is impaired, but supervision is preserv ed in depression, whereas both initiation and supervision are impaired in schizophrenia. (C) 1998 Elsevier Science B.V. All rights reserved.