Working Memory Deficit as a Risk Factor for Severe Apathy in Schizophrenia: A 1-Year Longitudinal Study

Abstract

Apathy, described as impaired motivation and goal-directed behavior, is a common yet often overlooked multidimensional psychopathological state in schizophrenia. Its underlying cognitive processes remain largely unexplored. Data was drawn from a longitudinal hospital study of patients with a DSM-IV diagnosis of schizophrenia; 137 (82.5%) participated at the 1-month follow-up and 81 (59.1%) at the 1-year follow-up. Apathy was assessed with the Lille Apathy Rating Scale, validated in French and in schizophrenia. Severe apathy, overall (total score > -13) and on 4 previously identified distinct dimensions, was considered. Episodic verbal learning was assessed with the California Verbal Learning Test, executive functioning with the Trail Making Test, the Six Element Test and the Stop Signal Paradigm and working memory with the Letter-Number Sequencing Test. After controlling for confounding variables, only episodic verbal learning was associated with severe overall apathy in the cross-sectional study. At 1 year, working memory was associated with an increased risk of severe overall apathy, adjusting for baseline apathy. Using a dimensional approach to apathy, specific types of cognition were found to be associated with specific dimensions of apathy. Our findings confirm the need for a multidimensional approach of negative symptoms in schizophrenia. Moreover, cognitive functioning could be a risk factor for developing severe apathy. Cognitive remediation may thus be a useful non-pharmacological intervention for treating apathy in schizophrenia patients.

Keywords: apathy; cognition; longitudinal study; negative symptoms.