New Insights of Transcranial Direct Current Stimulation (tDCS) for Preventing Amphetamine Use and Relapse: Results of a 6-month Follow-up
Description
Hypothesis: (1) we intended to examine whether the traditional therapy (anodal tDCS over right DLPFC, cathodal tDCS over left DLPFC, with drug cues exposure) could effectively reduce the subjective craving. (2) We tested whether the new method (anodal tDCS over left DLPFC, cathodal tDCS over right DLPFC, with negative self-appearance exposure) could enhance self-concept and reduce drug craving. (3) And to see whether the stimulation effect on drug craving and relapse of new method would be longer. Data Collection: 54 amphetamine addicts were randomized to three groups (self group, anodal tDCS on left dorsolateral prefrontal cortex (DLPFC) with self-picture presentation; drug group, anodal tDCS on right DLPFC with drug pictures presentation; control group, routine treatments as usual) for a 40-day tDCS (10 sessions, 2mA, 15min) treatment. Levels of drug craving and self-concept were measured before, immediately after and 6 months after the intervention.Demographic information was also included. Results: Compared to control group, drug craving in two experimental groups significantly decreased after stimulation, and self-concept in self group significantly increased. 6-month follow-up measurement showed that treatment effect on both drug craving and self-concept remained in self group. While the direct effect of tDCS in drug group failed to endure in the 6-month follow-up. Conclusions: This study explored a new protocol of addiction treatment. Improving self-concept seems more effective than direct intervention of cue-induced drug craving, which can not only reduce drug craving, but also enhance participant’s ability to resist drug relapse. Self-concept maybe an important psychological construct for drug abuse. Data description: Except for using a visual analog scale (VAS) to assess their subjective drug craving and self-concept, we also used Obsessive Compulsive Drug Use Scale and Self-esteem Scale to measure drug craving and self-esteem respectively. Total score and every item score were reserved in our dataset.
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tDCS stimulation: Low-intensity transcranial DC Stimulator made by the American Soterix medical company was used in our experiment. The sites for stimulation (i.e., left DLPFC, right DLPFC) was determined by the International 10/20 Electroencephalogram System. For all participants, the electrode (5 cm x 7 cm) was programmed, while the direct current was set as 2 mA. The tDCS stimulation procedure was maintained for a total of 15 minutes. Current intensity and the state of the patients had undergone real-time monitoring when the tDCS stimulation procedure began. Cues:The images used in the tDCS intervention were programmed using the E-Prime 2.0 software. A total of 10 images were presented in a random cyclic order, and each image appeared five times. All images underwent standardized processing and were of uniform size (i.e., 450 mm x 336 mm) to ensure that they were clearly and completely displayed on the computer screen. The degree of familiarity and emotional arousal of drug images were assessed by 20 drug addicts in preparation for the experiment. Self-related images were also assessed and selected by two research assistants (who were blind at the experiment). Measurements Cravings: Immediately after each session of treatment, participants were invited to answer the question “Now, how much do you want meth?” using a visual analog scale (VAS) to assess their subjective feeling (with 0 being “not at all” and 10 representing “extremely”). Obsessive Compulsive Drug Use Scale (OCDUS, 13 items, 1–5 points, separately representing craving intensity “No, less, medium, more, very much”) was used before and after the entire experiment as well as follow-up measurement. Self-concept: Immediately after each treatment session, participants in self group answered the question “Now, how satisfied are you with yourself?” using a visual analog scale (VAS) to assess their subjective feeling (with 0 being “not at all” and 10 representing “extremely”). Self-esteem Scale (SES) was used to understand how the participants look at themselves before, immediately after and 6-month after the entire experiment, with 1 being “very consistent” and 4 representing “not consistent at all”. Data analyses SPSS was used for all statistical analyses. We applied a repeated measures ANOVA with measure (pre-tDCS, post-tDCS vs. Follow-up) as within-subjects variable and group as between-subjects variable for the drug craving of all participates. A similar analysis was also applied for self-esteem.