Comparison of the Characteristics of Anhedonia between Patients with Schizophrenia and Depressive Disorder

OBJECTIVES: Anhedonia, defined as an inability to experience pleasure, has been considered to be a core feature of schizophrenia and depression. The purpose of the present study was to compare the specific characteristics of anhedonia in patients with the two illnesses by examining hedonic capacity during phased hedonic experience. METHODS: Hedonic rating tasks, using the film clips of physical and social hedonic stimuli and neutral stimuli, were performed by 29 patients with schizophrenia, 20 patients with depression, and 29 normal controls. Each task consisted of 'preview phase' with insufficient emotional information, and a subsequent 'theme phase' with sufficient emotional information. RESULTS: In normal controls, the mean hedonic score was increased in the theme phase compared with the preview phase, suggesting an appropriate augmentation of the hedonic response. In patients with schizophrenia, hedonic scores in the preview phase were comparable with those in normal controls, but showed deficient augmentation in the theme phase. In patients with depressive disorder, the range of increments in scores between the preview and theme phases was normal, but the scores themselves were lower in both phases than in the other two groups. CONCLUSION: The results indicate that patients with schizophrenia show a deficient augmentation of the hedonic response, whereas patients with depressive disorder have a pervasive lack of hedonic capacityope