Anhedonia, traditionally defined as a diminished capacity to experience pleasure, has long been considered a core feature of schizophrenia. Modern studies indicate that interview-based ratings of anhedonia predict a number of important clinical outcomes, such as disease liability, subjective quality of life, community functional outcome, and recovery. Unfortunately, attempts to remediate anhedonia via pharmacological and psychosocial interventions have been ineffective. Limited progress in treating anhedonia is due in part to poor conceptual clarity regarding emotional experience abnormalities in schizophrenia. Prior studies indicate that ratings of anhedonia made on clinical interviews are best conceptualized as a reduction in the frequency of pleasurable activity, rather than a deficit in initial reward responsiveness or hedonic capacity. This raises an important question: why do apparently normal hedonic responses not translate into motivated behaviors aimed at obtaining rewards in schizophrenia? The goal of the current project is to answer this question by applying a novel conceptual framework that explains anhedonia as resulting from abnormalities in the temporal dynamics of emotion. A well-validated approach to studying the temporal dynamics of emotion in the context of every day activities will be implemented, Ecological Momentary Assessment (EMA). People diagnosed with schizophrenia (n = 84) and demographically matched healthy controls (n = 84) will complete three types of EMA surveys (signal-contingent, interval-contingent, and event-contingent) of emotional experience at multiple time points in the day, over the course of 7 days. Mathematical modeling approaches, such as network analysis and Markov chain analysis, will be applied to the EMA data to evaluate stochastic dynamic changes in emotional states to determine how they interact, unfold over time, and influence real-world reward-seeking behavior. Using mathematical modeling, we aim to extend our preliminary data indicating that reductions in the frequency of pleasurable activity reflect deficits in the sustained responsiveness to reward in people with schizophrenia. Findings will provide a specific, mechanistic account of anhedonia that can be used to develop novel treatment targets for technology-based Ecological Momentary Interventions.
In the United States, schizophrenia is the leading cause of medical disability, resulting in extremely high rates of unemployment and high financial costs to the public healthcare system. Due to the critical role that anhedonia plays in functional disability in schizophrenia, it is critical that progress be made in understanding its underlying mechanisms, in order to develop effective treatments. The goal of the current project is to investigate the temporal dynamics of emotional experience during everyday life in people with schizophrenia to identify potential treatment targets for anhedonia.
