Fractionation of executive function in schizophrenia: Relationships to clinical and neurological manifestations

Abstract

Cognitive neuropsychological theories hypothesize that frontal executive deficits play a role in the etiology of schizophrenic symptoms. Recent evidence also suggests that the dysexecutive syndrome may be fractionated. The successful attempts in fractionating the executive system will depend to a considerable extent on the ability to develop more specific models of executive function. The current conventional frontal tests used by clinicians and neuropsychologists tend to be crude and underspecified in terms of the cognitive processes which they engage. These may not be sensitive enough to detect executive dysfunction in clinical groups like schizophrenia. Here we would like to adopt a systematic approach of examining executive function according to the theoretical models identified from the literature (some of them were based on animal studies). We then discuss how fractionation of executive function in schizophrenia could be studied with the extended design of single-case study to multiple-case study. Evidence will be provided on the differential breakdown of executive function components in this chronic and medication naïve cases. We also attempt to build up a link between specific executive function components to subtypes of clinical symptoms and neurological deficits. Imaging data will also be provided to explore such a relationship.