Adaptive reward pursuit in individuals with high levels of schizotvby and batients with schizophrenia: evidence from both longitudinal and cross-sectional studies
Reward motivation refers to the willingness to exert efforts to pursue potential rewards. Adaptive reward pursuit makes it possible for an individual to flexibly adjust their willingness in time according to the effort-reward computation. When the effort-reward ratio changes, whether an individual can adjust his or her reward motivation in time is particularly important for one to maintain mental health.
The adaptability of reward motivation is easily affected by diseases, personality traits and environmental stress factors. Previous studies mainly focus on the possible reasons underlying the insufficient reward motivation of schizophrenic patients and individuals with schizophrenic traits, but little attention has been put on whether they could dynamically adjust their reward motivation according to the changes in the effort-reward ratio in the environment. This is a new direction for researchers to evaluate the reward motivation. It will reveal the possible mechanism underlying the deficits of their social adaptability in patients and subclinical individuals. The current project systematically examined how reward motivation changes with external effort-reward ratio and schizotypal traits by longitudinal and cross-sectional studies.
Moreover, we examined whether patients with schizophrenia would adjust their reward motivation according to the effort-reward ratio in laboratory settings and whether there is a relationship between the adaption of reward motivation and the patients' social function.
In study 1，effort-reward ratio, schizotypal traits, anticipatory pleasure experience and reward motivation were assessed by scales in college students at two time points in the one-year intervals. The serial mediation model revealed that baseline negative or disorganized schizotypal traits and pleasure experience partially mediated the prediction of baseline effort-reward ratio on the reward motivation one year later. It indicated that the interaction between effort-reward imbalance and schizotypal traits would affect the reward motivation one year later. The anticipatory pleasure experience partially ameliorated the influence of schizotypal traits exerted on the one-year-end-point reward motivation. Negative and disorganized schizotypal traits were the risk and the anticipatory pleasant experience was the protective factor of reward motivation.
In order to further reveal the dynamic adjustment of reward motivation, Study 2 collected the scale data of schizotypal traits, effort-reward ratio, anticipatory pleasure experience and reward motivation at five time points (3-month intervals) in a year. The results showed that the effort-reward ratio at the previous time point would predict the negative schizotypal traits at the following time point. The negative schizotypal traits at the previous time point would further predict the reward motivation at the following time point. This suggests that the effort-reward ratio and the negative schizotypal traits would be the causal factors to explain the decline of reward motivation.
In study 3, the reward motivation adaptation behavioral task was conducted at two time points in one year. All the participants were clustered into three groups: high schizotypal traits group, negative schizotypal traits group and the low levels of schizotypal traits group. Whether their reward motivation would be changed with effort-reward ratio and whether their reward motivation adaption remained stable during a year was examined in this study .The results indicated that the reward motivation of negative schizophrenic trait individuals remained intact in reward motivation adaptation. Such adaptability remained stable during a year. This suggests that individuals with schizotypal traits, including negative schizotypal traits, remained intact in the reward motivation adaptation. Such reward motivation adaptation is stable.
In study 4, the reward motivation adaptation behavioral task was used to investigate whether patients with schizophrenia have deficits in reward motivation and whether their adaptability was associated with their social function. The results showed that compared with the healthy controls, the reward motivation in patients with schizophrenia could not be enhanced with the decrease in effort-reward ratio. This is correlated with the patient's social function and the level of reward motivation in life. This result reveals the cognitive mechanism underlying poor social adaptability in patients with schizophrenia.
In conclusion, reward motivation could be predicted by the interaction among schizotypal traits, anticipatory pleasure and effort-reward ratio. Moreover, patients with schizophrenia, rather than individuals with schizotypal traits, have deficits in adaptive reward pursuit. These findings are helpful in further understanding the mechanism of how motivation changes with effort-reward ratio in individuals with schizophrenia spectrum disorders. The current study provides a new point of view to evaluate the reward motivation in a dynamic way.
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