Behavioral validation of avolition in schizophrenia

Abstract

BackgroundSince Kraepelin, avolition, a core symptom of schizophrenia, has been defined as a decrease in spontaneous, self-initiated and purposeful behaviors observed in daily life activities. However, the concurrent validity of commonly-used avolition measures has not been studied, and direct observation may offer a more objective way to measure avolition. MethodA direct observation measure of spontaneous and self-initiated behaviors that can be observed in an inpatient setting was defined with the use of time sampling method. This direct observation measure was used with fifty inpatients with schizophrenia. Additionally, patients were asked to rate their current interest in and their level of engagement in 10 active behaviors during the preceding 7days. Clinicians rated the patients' engagement in the same activities for the preceding 7days as well. ResultsThe direct observation measure showed very good psychometric properties. Three clinical negative symptom scales showed moderate to high correlation with the direct measure. Concerning the retrospective ratings, patients' self-assessments were poorly correlated with clinicians' ratings, but showed high correlation with their subjective interests. ConclusionsClinical rating scales of negative symptoms show moderate to good concurrent validity as measures of avolition in schizophrenia. However, patients' self-reports do not appear to provide valid indices of avolition. Our results favor clinical negative symptoms scales that use observers' reports only, over patients' self-reports. The direct observation of patients' behavior offers a precise and objective measure of avolition that may be useful in drug challenges and clinical trials.