Enhanced neural responses to monetary rewards in methamphetamine use disordered individuals compared to healthy controls.

Converging evidence supports that addiction involves the pathological usurpation of normal reward processes. However, the nature and direction of reward processing dysfunction in substance abusers remain unclear. The current study explored the electrophysiological responses associated with different stages of reward processing in methamphetamine (MA) use disordered individuals. Electroencephalography recording was used to compare responses of 21 MA use disordered individuals and 22 healthy controls (HC) while participants engaged in a simple gambling task. Compared to HC, MA use disordered individuals made more risky choices following a loss outcome on a previous trial. During the reward anticipatory stage, MA use disordered individuals showed an enhanced stimulus-preceding negativity (SPN), as compared to HC. During the reward outcome stage, MA use disordered individuals showed an enhanced feedback-related negativity (FRN) for the losses versus gains as compared to HC. Furthermore, an enhanced P300 was observed under the gain condition, but not under the loss condition, in MA use disordered individuals as compared to HC. These findings provide further evidence that MA use disordered individuals have a sensitized neural response to non-drug rewards and support the impulsivity and incentive sensitization theories in MA use disordered individuals. The current study helps to elucidate the neural mechanisms of reward processing in MA use disordered individuals.