Cognitive effort in Schizophrenia: Dissimilar effects on cardiovascular activity and subjective effort

Abstract

This study investigated objective and subjective cognitive effort as a function of task difficulty in schizophrenia, based on the principles of motivational intensity theory. Thirty individuals with schizophrenia and 30 healthy controls worked on four levels of a working memory task ranging from easy to extremely difficult. We assessed objective effort as cardiovascular activity during task performance and subjective effort via self-report. In addition, we assessed participants' task performance, negative symptoms, amotivation, depression, and fatigue. Cardiovascular activity during the task increased only in the healthy control group, but not in the schizophrenia group, indicating attenuated objective effort in schizophrenia. However, individuals with schizophrenia reported similar levels of subjective effort as healthy controls. Moreover, we found a negative association between fatigue and cardiovascular activity only in the schizophrenia group. Our results show a dissociation between objective and subjective effort in schizophrenia, which may explain decreased willingness to mobilize cognitive resources in individuals with schizophrenia. Moreover, our results highlight the importance of fatigue in effort in schizophrenia, a variable rarely considered in the current literature.