Blunted anterior midcingulate response to reward in opioid users is normalized by prefrontal transcranial magnetic stimulation

IntroductionAbnormalities in goal-directed behavior, mediated by mesocorticolimbic reward function and structure, contribute to worse clinical outcomes including higher risk of treatment dropout and drug relapse in opioid users (OU). Material and MethodIn a sham-controlled randomized study design, we measured whether robot-assisted 10Hz transcranial magnetic stimulation (TMS) applied to the prefrontal cortex was able to modulate anterior midcingulate cortex (MCC) electrophysiological response to rewards, in OU and matched healthy controls. ResultsWe show that OU exhibit a blunted anterior MCC reward response, compared to healthy controls (t(39) = 2.62, p = 0.01, d = 0.84), and that this is normalized following 10-Hz excitatory TMS (t(36) = .82, p = 0.42, d = 0.17). ConclusionsExcitatory TMS modulated the putative reward function of the MCC in OU. Further work with increased sample sizes and TMS sessions is required to determine whether restoring MCC reward function increases reward-directed behaviors, which may enhance treatment success through the maintenance of treatment goals.