Reward prediction errors drive reinforcement learning and episodic memories: gender differences in individuals with methamphetamine use disorder

Abstract

Abstract Background Individuals with methamphetamine (MA) use disorder have impaired executive functioning with gender differences, which may be related to the reward prediction errors (RPEs) that drive reinforcement learning and episodic memories, as RPE signaling is impaired in these individuals. Objectives We examined whether the driving effects of RPE on reinforcement learning and episodic memories are impaired in individuals with MA use disorder and how differ between women and men. Methods A total of 82 individuals with MA use disorder in abstinent (MA group: 47.6% female) and 86 non-users (control group: 47.7% female) were recruited and required to learn the mean value of a reward in a learning situation. Reward prediction error was manipulated by giving different monetary reward feedback after each reward prediction. Results Compared to non-users, the MA group had lower learning rate for rewards and recognition-memory accuracy for items. The effect of reward prediction error showed a dissociable effect on gender: absolute prediction error had an impaired driving effect on reinforcement learning and episodic memories in the female MA group, but not in the male MA group. Conclusion Males with MA use disorder can learn from unexpected reward feedback, but females are less able to learn much, and their episodic memories of past feedback results could not guide them to make adaptive behaviors. The gender difference may explain the greater impairment in some executive functions and greater involvement in criminal activity among females with MA use disorder.