Impulsive Behavior Characteristics Of Methamphetamine Addicts And Transcranial Direct Current Stimulation Intervention

Methamphetamine（MA）is the most prevalent drug in China.Methamphetamine abuse can lead to mental and physical problems such as depression,anxiety,sexually transmitted diseases and cardiovascular complications.Chronic methamphetamine use leads to impairment of brain structure,metabolism and functional connectivity,which in turn impairs mood regulation and cognitive function,including impulse control,in addicted individuals.Impulsivity is the core feature of methamphetamine addiction,which has an important impact on the occurrence,development and withdrawal of addiction.Therefore,two studies were carried out in this paper.The first one was to explore the impulsive behavior characteristics of methamphetamine addicts,and the second one was to explore the effects of transcranial direct current stimulation on the impulsivity of methamphetamine addicts.Study 1 recruited 45 eligible male methamphetamine addicts and 25 healthy adult males who served as a control group.The health control group was matched with the methamphetamine addiction group in terms of age,education level,smoking habits,anxiety level,depression level and impulsivity.The two-choice oddball task was used to measure behavioral impulsivity,the Stroop task to measure attentional impulsivity,and the Iowa gambling task to measure unplanned impulsivity.Two groups of subjects completed all three impulsive behavior tasks after completing the informed consent form and questionnaire.The order of tasks is balanced by Latin squares.The results showed that,relative to the healthy group,the methamphetamine-addicted group had lower bias stimulus accuracy on the two-choice oddball task,lower net score on the Iowa gambling task,and no significant difference on the Stroop task.Study 2 and Study 1 used the same group of methamphetamine addicts,who were randomly assigned to a true stimulus group（23）and a sham stimulus group（22）.The subjects in the active and sham groups received the intervention of active and sham transcranial direct current stimulation at the same time in the same position.Transcranial direct current stimulation was administered once a day for 5 days.The behavioral outcomes of the two-choice oddball task,the Stroop task and the Iowa gambling task were used as measures of impulsivity.The results showed that there was no significant difference before and after the test in the sham group,indicating that conditional control was effective.For the active group,five days after the intervention,there was a significant decrease in the bias stimulus accuracy of the two-choice oddball task,while the net score of the Iowa gambling task and the accuracy and reaction time of the Stroop task did not change significantly.Two studies were conducted to explore the characteristics of impulsive behavior in methamphetamine addicts and the effects of transcranial direct current stimulation on them.Specifically,methamphetamine-addicted individuals had higher behavioral impulsivity and unplanned impulsivity than healthy individuals.In addition,which found that it could reduce the craving of methamphetamine addicts,this study shown that 5consecutive days of bilateral dorsolateral prefrontal transcranial direct current intervention counterproductively increased the behavioral impulsivity of methamphetamine addicts,but had no significant effect on attention impulsivity and nonplaning impulsivity.The possible reason is that methamphetamine causes the DLPFC to overdraw and cannot withstand the activation intervention of t DCS.In future studies,the relationship between the dorsolateral prefrontal cortex and impulsivity in methamphetamine addicts needs to be further explored to explore a more suitable transcranial direct current stimulation intervention protocol for methamphetamine addiction.