The functional outcome of executive impairments in the psychomotor poverty syndrome: Verbal working memory may mediate the relationship between memory and real-life skills

Abstract

This study investigated whether executive impairments are predictive of the poor functional outcome found in the Psychomotor Poverty syndrome of schizophrenia. Functional impairments in a supermarket-shopping task were investigated in a cross-sectional study of three groups of participants: those with and those without psychomotor poverty symptoms and normal controls. Groups were matched for age, sex, premorbid IQ and memory function. Novel measures of real-life skills were developed which emphasised relevant executive processes within the shopping task. Four executive tasks were also administered which provided six measures of working memory, initiation and strategy use. The psychomotor poverty group demonstrated verbal working memory, spatial strategy and verbal initiation impairments and greater impairment in functional accuracy and strategic efficiency on the shopping task compared to the non-psychomotor poverty group and normal controls. The nonpsychomotor poverty group were more efficient than controls in some real-life skills. Verbal working memory independently predicted functional accuracy and efficiency in relation to other executive processes. Neither verbal working memory nor general memory independently predicted accuracy or the majority of efficiency measures. Experimentally determined executive impairments are ecologically valid in their impact on functional outcome in schizophrenia. Verbal working memory may constitute an important mediator of the relationship between poor verbal memory and poor functional outcome in the psychomotor poverty syndrome. These findings provide a theoretical framework through which cognitive remediation programmes may be developed to enhance generalisable executive and real-life skills and improve the poor functional outcome in the psychomotor poverty syndrome of schizophrenia.