Schizophrenia is a complex psychiatric disorder characterized by a reduced ability to motivate effortful behavior and experience pleasurable events, i.e., amotivation and anhedonia, leading to a wide range of impairments in social functioning. However, the putative neurobiological mechanisms for amotivation and anhedonia are still unclear, hindering the development of effective interventions targeting at amotivation and anhedonia.

A recent theoretical framework suggests that impaired reward functioning may be one of the putative neurobiological mechanisms underlying amotivation and anhedonia in schizophrenia.

According to this theoretical framework, reward processing can be divided into reward anticipation (the ability to anticipate pleasurable events or imminent rewards), reward consumption (the ability to experience pleasure upon receipt of the reward), reward learning (the ability to maintain and update the internal representation of rewards), and effort computation (the decision to make and computation of the effort required to approach the reward).

Dr. Raymond Chan from the Institute of Psychology of the Chinese Academy of Sciences and his collaborators conducted a meta-analysis to further illustrate the neurobiological mechanisms associated with amotivation and anhedonia in schizophrenia. They adopted a "component-based approach" for reward processing and a "whole brain perspective" for neural mechanisms.

Their results showed that schizophrenia spectrum patients exhibited reduced activation in the striatum, orbital frontal cortex, cingulate cortex, and cerebellar areas.

They also found different patterns of brain alterations for different components. Reward anticipation was correlated with decreased activation in the cingulate cortex and striatum. Reward consumption was correlated with decreased activation of the cerebellum IV/V areas, the insula, and the inferior frontal gyri. With respect to reward learning, it was correlated with decreased activation of the striatum, thalamus, cerebellar Crus I, cingulate cortex, orbitofrontal cortex, and some parietal and occipital areas.

Taken together, the researchers suggest that both reward anticipation and reward learning components are associated with reduced activation in the dorsal striatum and posterior cingulate cortex in people with schizophrenia spectrum disorders.

This meta-analysis provides a comprehensive examination of multiple components of reward processing in schizophrenia spectrum disorders. The findings support the compartmentalization of reward processing in schizophrenia spectrum disorders and also highlight the important role of impaired cerebellar connectivity in the development of amotivation and anhedonia in schizophrenia patients and individuals at risk for schizophrenia.  

This study was supported by the Jiangsu Provincial Key Research and Development Programme, the Scientific Foundation of the Institute of Psychology and the Phillip K.H. Wong Foundation. 

Areas with abnormal activation related to reward anticipation (purple), reward consumption (blue), and reward learning (red) in SCZ spectrum. (Image by Dr. Raymond Chan)