Abstract
BackgroundPrevious studies have identified the treatment effect of repetitive transcranial magnetic stimulation (rTMS) on cravings of patients with methamphetamine use disorder (MUD). However, the mechanism underlying the treatment effect remains largely unknown. A potential candidate mechanism could be that rTMS over the dorsolateral prefrontal cortex (DLPFC) modulates the attention bias to methamphetamine-related cues. The purpose of this study is therefore to determine the modulation of rTMS on methamphetamine-related attention bias and the corresponding electrophysiological changes.MethodsForty-nine patients with severe MUD were included for analysis. The subjects were randomized to receive the active intermittent theta-burst stimulation (iTBS) or sham iTBS targeting DLPFC for 20 sessions. Participants performed the Addiction Stroop Task before and after the treatment while being recorded by a 64-channel electroencephalogram. Baseline characteristics were collected through the Addiction Severity Index.ResultsPost-treatment evaluations showed a reduced error rate in discriminating the color of methamphetamine words in the active iTBS group compared with the sham iTBS group. Following rTMS treatment, we found the significant time-by-group effect for the N1 amplitude (methamphetamine words > neutral words) and P3 latency (methamphetamine words > neutral words). The change of N1 amplitude was positively correlated with cravings in the active group. Moreover, reduced power of neural oscillation in the beta band, manifesting at frontal central areas, was also found in the active group.ConclusionThis study suggests that attention bias and the beta oscillation during the attentional processing of methamphetamine words in patients with MUD could be modulated by iTBS applied to left DLPFC.
Highlights
Repetitive drug use and the formation of addiction are generally believed to be related to the responses to substance-related cues (Courtney et al, 2016)
There were no significant differences between the active (n = 30) and sham intermittent thetaburst stimulation (iTBS) (n = 19)
Post hoc analysis showed no significant change in N1 AmplitudeMA−Neutral in both active iTBS group (t = 1.50, corrected p = 0.284) and sham group (t = −1.49, corrected p = 0.29)
Summary
Repetitive drug use and the formation of addiction are generally believed to be related to the responses to substance-related cues (Courtney et al, 2016). According to the integrated model proposed by Franken (2003), attention bias is the result of classical conditioning. This model suggests that the conditioned substance-related cue stimuli induce a dopaminergic response. These stimuli are taken as “salient” and attract the attention of patients. Previous studies have identified the treatment effect of repetitive transcranial magnetic stimulation (rTMS) on cravings of patients with methamphetamine use disorder (MUD). A potential candidate mechanism could be that rTMS over the dorsolateral prefrontal cortex (DLPFC) modulates the attention bias to methamphetamine-related cues. The purpose of this study is to determine the modulation of rTMS on methamphetamine-related attention bias and the corresponding electrophysiological changes
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