| The treatment of drug addiction has become a worldwide problem,and the emergence of new psychoactive substances has also brought new challenges to global drug control.To reduce the harm of drugs,all governments have made great efforts,and the research of this field has been continuing.Recent studies have shown that using extracranial nerve regulation technique like t DCS to stimulate dorsolateral prefrontal cortex(DLPFC)plays a significant role in reducing drug craving,improving impulse control ability and moods,and prolonging the time interval of relapse.However,the methods of stimulating electrode placement are not consistent in the existing research results,so there is no comparative study on whether t DCS is more effective in activating unilateral DLPFC or changing the current between bilateral DLPFC,and whether activation of left-side DLPFC or right-side DLPFC is more effective.In addition,although a large number of studies have reported significant effects of t DCS on DLPFC in drug addiction intervention,there is no unified conclusion on the number of reasonable t DCS in drug addiction intervention.Therefore,this study took meth addicts as subjects to compare the effect of different t DCS electrode placement methods on reducing meth craving and impulsivity.On this basis,a dose study and a 3-month follow-up study were conducted to explore the effects of different t DCS stimulation times on drug craving,impulsivity,emotion and cognitive control of addicts,so as to provide a reference for the development of clinical detoxification work.Participants in the study were 135 meth addicts aged between 18 and 40 in a rehab facility,90% of whom had a junior high school education or above.In study 1,85 meth addicts were randomly assigned to five groups,all of which were identical except for the placement of the electrodesIn study 1,85 meth addicts were randomly assigned to 5 groups,all of which were subjected to a single t DCS stimulation with a stimulus parameter of 15 min and 1.5ma,with the exception of electrode placement.Meth craving visual simulation questionnaire and impulsivity questionnaire were used as evaluation indexes.The results before and after the test showed that the changes of indicators in all groups were not significant,but compared with the other groups,the drug craving degree and impulsivity of the subjects in experiment 2 group showed a decreasing trend.This result suggests that placing the anode t DCS on the right side of the DLPFC and the cathode t DCS on the right shoulder may be an effective stimulus to reduce meth cravings and impulsivity.In study 2,another 60 addicts were randomly divided into four groups,each group receiving 15 stimuli,in which the first group was the control group(only the sham stimulus was received),and the other three groups were the experimental group,(group1:5 real stimulus,10 sham stimulation;group2:10 real stimulus,5 sham stimulation;group3: 15 real stimulation).The stimulation parameters were 15 min and1.5 m A,and the anode electrodes were placed on the right DLPFC,cathode on the right shoulder.The subjects received stimulation every other day.The assessment tools used included drug craving questionnaire,obsessive drug use scale,impulse scale,go/no-go test,implicit association test.The results of pre-and post-test showed that:(1)in terms of meth craving,visual simulation scale scores showed that the craving levels of subjects in the control group,experimental group 1 and experimental group 2 were significantly decreased,while the scores of compulsive drug use scale showed that the craving levels of addicts in experimental group 2 were significantly decreased;(2)in terms of impulsivity,the score of impulsivity scale in experimental group 2 and experimental group 3 decreased significantly;(3)In terms of emotional indicators,anxiety levels in experimental group 2 and experimental group 3 significantly decreased,and depression in experimental group 2 significantly improved;(4)in terms of cognitive indicators,the accuracy of experiment group 2 and experiment group 3 in the go-nogo task increased,and the response time of experiment group 2 significantly increased.In the single target implicit association test,there was no significant difference in the response time between the drug-positive and drug-negative tasks in each group.In the post-test,the “drug-negative” accuracy was significantly higher than the “drug-positive”accuracy in the group 2 and group 3.Study 2 is a further verification of the results of study 1,and proved that multiple t DCS stimulation of the right DLPFC can significantly reduce the level of craving,impulsivity,improve anxiety,depression and improve inhibitory control ability,and the effect of 10 times intervention is the best.Study 3 was a continuous follow-up of study 2 results to determine the relationship between the number of stimuli and the duration of the stimulus effect.The results of three months of follow-up showed that :(1)in meth craving,the subjective craving level of experimental group 1 and experimental group 2 was still significantly lower than the baseline level;the effect of intervention on compulsive drug use also persisted for three months in the two and three groups.(2)in terms of impulsivity,there was no difference between the tracking data of impulsivity and the baseline level in each group;(3)in terms of emotional indicators,anxiety and depression of all subjects relapsed,and anxiety level of the experimental group 2 was still significantly lower than its baseline;(4)in terms of cognitive indicators,the response time and accuracy of the subjects in the go-nogo task were almost the same as the baseline level.In the single target implicit association test,the drug-negative accuracy was significantly higher than the drug-positive accuracy in the tracking of experimental group 2 and experimental group 3.The results of study 3 showed that there was a nonlinear relationship between the number of t DCS stimulation and the maintenance of stimulation effect,and the effect of 10 t DCS interventions could be maintained for three months.This study has reached the following conclusions:1.The stimulation method of placing the anode t DCS on the right DLPFC and the cathode t DCS on the right shoulder has the best effect in reducing drug cravings and impulsivity of meth addicts.2.Repeated t DCS stimulation reduces drug cravings,impulsivity,depression and anxiety,and is associated with improved cognitive function.3.10 t DCS stimulation is optimal and the effect of drug craving and anxiety reduction and cognitive improvement can be maintained for at least 3 months.4.The cumulative effect of t DCS is not linear with the number of stimuli.This study explored the basic issues of electrode placement in the application of t DCS in meth addiction intervention,and it was applied to the clinical practice of meth addiction intervention to explore the reasonable stimulation times to achieve good intervention effect.It provides a reference for the large-scale application of t DCS and the improvement of the equipment use efficiency in the forced isolation of drug addicts. |
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