Anhedonia and amotivation are key features of negative symptoms observed in patients with schizophrenia. In particular, amotivation refers to the diminished volition to initiate or maintain goal-directed behaviour that may be underpinned by different impairments of reward valuation. Range adaptive valuation or coding is considered to be one of the factors contributing to amotivation in patients with schizophrenia. It is defined as the ability to discriminate reward values refers to range adaptive valuation. However, it is still not fully known whether range adaptive valuation has been altered or impaired at different stages of schizophrenia.
In order to address such an issue, Dr. Raymond Chan’s team from Neuropsychology and Applied Cognitive Neuroscience (NACN) Laboratory, the CAS Key Laboratory of Mental Health, Institute of Psychology has conducted a study to examine valuation of rewards and range adaptive coding in individuals along the continuum of schizophrenia. They recruited 30 pairs of patients with chronic schizophrenia and their controls, 30 pairs of patients with first-episode schizophrenia and their controls, and 34 pairs of individuals with high and low levels of social anhedonia to complete a task specifically designed to capture range adaptive coding. This task required the participants to make decision on whether to choose a high-effort or low-effort physical gripping condition based on probability and reward magnitude.
Their results showed that patients with chronic schizophrenia showed over-adaptation to the value range and their performances were positively correlated with self-reported consummatory interpersonal pleasure. On the other hand, patients with first-episode schizophrenia exhibited diminished value adaptation, which was correlated inversely with avolition severity and positively with the overall proportion of choosing to exert ore effort. Finally, individuals with high level of social anhedonia exhibited comparable range adaptive with individuals with low level of social anhedonia. However, these high level social anhedonia individuals did show negative correlation between value adaptation performances and the proportion of choosing to exert more effort under the lowest value condition of the behavioural task. Taken together, these findings suggest a dysfunction in range adaptation in individuals along the spectrum of schizophrenia, ranging from patients with established clinical diagnosis to individuals with subclinical features of psychopathology. Such range adaptation may index a potential underlying mechanism of amotivation in schizophrenia spectrum disorders.
Dr. Chan’s team is now undertaking studies to investigate the underlying neural mechanism of range adaptive valuation in schizophrenia spectrum disorders and other mental disorders sharing similar clinical manifestations using task-based neuroimaging and magnetic resonance spectroscopy paradigms. They hope these studies will open a new window for us to understand amotivation and anhedonia in schizophrenia spectrum disorders and other mental disorders.
This study was supported by grants from the National Key Research and Development Programme, the Jiangsu Provincial Key Research and Development Programme, the Beijing Municipal Science and Technology Commission Grant, and the CAS Key Laboratory of Mental Health, Institute of Psychology.
This study is now published online on August 22, 2021 in Schizophrenia Bulletin
Wang, L. L., Lam, C. Y. T., Huang, J., Cheung, E. F. C., Lui, S. S. Y., Chan, R. C. K.* (2021). Range-adaptive value representation in different stages of schizophrenia: A proof of concept study. Schizophrenia Bulletin.
- Wang J, Huang J, Lui SSY, Cheung EFC, Yue XD, Chan RCK. (2018). Motivation deficits in individuals with social anhedonia. Psychiatry Research. 261: 527–534.
- Wang, J., Huang, J., Yang, X. H., Lui, S. S. Y., Eric, E. F. C., Chan, R. C. K. (2015). Anhedonia in schizophrenia: deficits in both motivation and hedonic capacity. Schizophrenia Research, 168: 465-474. doi:10.1016/j.schres.2015.06.019
Institute of Psychology
Chinese Academy of Sciences
Beijing 100101, China.