Lack of effect of methamphetamine on reward-related brain activity in healthy adults

Introduction Stimulant drugs are thought to alter processing of rewarding stimuli. However, the mechanisms by which they do this are not fully understood. Method In this study we used EEG to assess effects of single doses of methamphetamine (MA) on neural responses during anticipation and receipt of reward in healthy volunteers. Healthy young men and women (N = 28) completed three sessions in which they received placebo, a low MA dose (10 mg) or a higher MA dose (20 mg) under double blind conditions. Subjective and cardiovascular measures were obtained, and EEG was used to assess brain activity during an electrophysiological version of the Monetary Incentive Delay (eMID) task. Results EEG measures showed expected patterns during anticipation and receipt of reward, and MA produced its expected effects on mood and cardiovascular function. However, MA did not affect EEG responses during either anticipation or receipt of rewards. Conclusions These findings suggest that the effects of MA on EEG signals of reward processing are subtle, and not related to the drug’s effects on subjective feelings of well-being. The findings contribute to our understanding of the neural effects of MA during behaviors related to reward.