The association between verbal memory, processing speed, negative symptoms and functional capacity in schizophrenia

The aim of this paper is to explore the links among verbal memory, processing speed, negative symptoms, and functional capacity, using structural equation modeling techniques. Model A is a multiple regression model with cognitive and symptom variables as predictors and functional capacity as the latent outcome variable. Model B consists of three two mediator models that assess the ability of each variable to mediate the effect of the other variable on outcome conditional on the inclusion of the other mediator in the model. Ninety-eight community-dwelling patients with schizophrenia (mean age=35.8years, S.D.=10.1) participated in the study. Results indicate that verbal memory, processing speed and negative symptoms significantly contributed to functional status. Verbal memory was at least partially mediated by processing speed in its effect on outcome, while the impact of processing speed on outcome was mediated by both verbal memory and negative symptoms. The influence of negative symptoms on functional capacity was partially mediated by processing speed. These findings enrich our understanding of the direct and indirect effects of these three interrelated variables and provide a basis for the development of intervention strategies.