Anhedonia is one of the core negative symptoms of schizophrenia and is defined as the inability to experience pleasure or reduced hedonic capacity. It is composed of two components, namely the anticipatory and consummatory pleasure. Recent works have shifted from investigating reduced hedonic capacity alone to both amotivation and reduced hedonic capacity. Amotivation could be operationalized into goal-directed behaviour and effort allocation decision-making to pursue a potential reward. However, it is not clearly known whether patients with schizophrenia prominent with negative symptoms would show both the deficits in motivation and hedonic capacity.

Dr. HUANG Jia and CHAN Raymond from the Institute of Psychology of Chinese Academy of Sciences have developed an innovative Effort-based pleasure experience task (E-pet) to examine whether reward motivation and hedonic capacity contributed the main features of schizophrenia patients characterized with prominent negative symptoms.

The researchers recruited 22 schizophrenia patients with prominent negative symptoms, 18 patients without prominent negative symptoms, and 29 healthy controls. The computerized test of the E-pet was administered to all the participants. The E-pet required the participants to make decisions on whether to choose a hard or easy task based on probability and reward magnitude. When making the grip effort allocation decision, schizophrenia patients with prominent negative symptoms were significantly less likely to choose a hard task than healthy controls.

Schizophrenia patients with prominent negative symptoms did not increase their hard task choices when the reward magnitude and the estimated reward value increased. These patients also showed significantly less likelihood to choose a hard task than healthy controls in medium and high probability conditions. Importantly, patients with prominent negatives symptoms reported significantly less anticipatory pleasure than healthy controls even when reward probability and magnitude increased. There were no significant differences between patients without prominent negative symptoms and healthy controls. However, in the consummatory pleasure experience phase, obtained reward predicted consummatory pleasure rating in all participants and patients with schizophrenia exhibited intact consummatory pleasure experience.

This study provides empirical evidence of impaired reward motivation and pleasure experience in patients with schizophrenia. The findings demonstrated that effort expenditure decision-making for maximum reward and anticipatory pleasure experience are both impaired in patients with schizophrenia and such impairment may be mediated by negative symptoms.

This study was done by the “Strategic Priority Research Program (B)” of the Chinese Academy of Sciences, the National Science Fund China and the Beijing Training Project for the Leading Talents in S & T.

The paper is now available online in Schizophrenia Research.