Regulation of Craving in Internet Gamers

Study Overview
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Brief Summary
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This project aims to investigate (1) the behavioral and neural mechanisms of regulation of craving in Internet gamers; (2) effects of tDCS over the dorsal lateral prefrontal cortex (dlPFC) on craving and regulation of craving and aversive emotions in this population. (3) effects of tDCS over dlPFC on attentional bias towards gaming related cues.This project will be conducted in Beijing, China, based on a large sample of Internet gamers.

Detailed Description
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As with the experiment about tDCS effects on regulation of craving and aversive emotions, the experiment aims to test whether tDCS over dlPFC will enhance cognitive regulation of craving and aversive emotions. It is a within-subject, sham-controlled, double-blind design. Each participant receive both active and sham tDCS of dlPFC in a randomized order separated by one week. During both active and sham tDCS sessions, participants will perform regulation of craving (ROC) and emotion regulation (ER) tasks. In the ROC task, participants will be asked to downregulate and upregulate craving elicited by gaming pictures using cognitive reappraisal. In the ER task, participants will be asked to downregulate and upregulate aversive feelings elicited by negative pictures using cognitive reappraisal. During these tasks, self-report ratings and skin conductance responses (SCRs) will be recorded. The cognitive regulation ability is indexed by rating and SCRs differences between the up- and downregulation conditions. As with the experiment about tDCS effects on attentional bias, the experiment aims to test whether tDCS over dlPFC will enhance inhibitory control of attentional bias towards gaming related cues. The inhibitory control of attentional bias will be measured by a cognitive task in which participants will perform a number classification task with gaming pictures and non-gaming pictures being distractors. The experiment is a within-subject, sham-controlled, double-blind design. Each participant will receive both active and sham tDCS of dlPFC in a randomized order separated by one week. After each tDCS session, participants will complete the cognitive task assessing inhibitory control of attentional bias. During the task, reaction times (RTs) wil be recorded. The attentional bias is indexed by RTs differences between trials with gaming pictures and trials with non-gaming pictures.

Official Title
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Regulation of Craving in Internet Gamers: Neural Mechanisms and tDCS Intervention

Conditions
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Internet Gaming Disorder

Intervention / Treatment
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* Other: active tDCS on the dlPFC
* Other: sham tDCS on the dlPFC


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: engagement in a popular Internet game (Arena of Valor) for over 14 hours per week for a minimum of 6 months. Exclusion Criteria: current or history of use of illegal substances and gambling; current or history of psychiatric or neurological illness; current use of psychotropic medications.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 30 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: within-subject, sham-controlled design: all subjects will receive active and sham tDCS in a randomized order
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: active tDCS on the dlPFC<br>tDCS on the DLPFC Dorsolateral prefrontal cortex (DLPFC) target will be identified by the baseline functional magnetic resonance imaging (fMRI) study for regulation of craving using a separate sample. During the intervention, each participant will receive an active transcranial direct current stimulation (tDCS) intervention on this DLPFC region (1.5 mA for 20 minutes). | Other: active tDCS on the dlPFC<br>* During active tDCS session, participants will perform the regulation of craving (ROC) and emotion regulation (ER) tasks. In the ROC task, participants will downregulate and upregulate craving elicited by gaming pictures using cognitive reappraisal. In the ER task, participants will downregulate and upregulate aversive feelings by negative pictures using cognitive reappraisal. After the active tDCS session, participants will complete a cognitive task assessing inhibitory control of attentional bias, in which participants will perform a number classification task with gaming pictures and non-gaming pictures being distractors. During the task, reaction times (RTs) wil be recorded.<br>* Other names: tDCS;|
| Sham Comparator: sham tDCS on the dlPFC<br>Each participant will also receive a sham tDCS intervention as a controlled condition. The sham tDCS only include a 30-s ramp up and a 30-s ramp down. | Other: sham tDCS on the dlPFC<br>* During the sham tDCS session, participants will perform the regulation of craving (ROC) and emotion regulation (ER) tasks. In the ROC task, participants will downregulate and upregulate craving elicited by gaming pictures using cognitive reappraisal. In the ER task, participants will downregulate and upregulate aversive feelings by negative pictures using cognitive reappraisal. After the sham tDCS session, participants will complete a cognitive task assessing inhibitory control of attentional bias, in which participants will perform a number classification task with gaming pictures and non-gaming pictures being distractors. During the task, reaction times (RTs) wil be recorded.<br>* Other names: tDCS;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Craving in the regulation of craving (ROC) task after the initiation of active and sham tDCS | Using the Visual Analog Scale (from 1 = 'not at all' to 9 = 'very much'), craving is assessed in the ROC task. This task lasts 12-13 minutes. Craving in the downregulation condition will be compared between the active and sham tDCS. Craving in the upregulation condition will also be compared between the active and sham tDCS. | 4 minutes after the initiation of active and sham tDCS for half of the participants | 
| Aversive feeling in the emotion regulation (ER) task after the initiation of active and sham tDCS | Using the Visual Analog Scale (from 1 = 'not at all' to 9 = 'very much'), aversive feeling is assessed in the ER task. This task lasts 12-13 minutes. Aversive feeling in the downregulation condition will be compared between the active and sham tDCS. Aversive feeling in the upregulation condition will also be compared between the active and sham tDCS. | 16-17 minutes after the initiation of active and sham tDCS | 
| Reaction times (RTs) in the cognitive task assessing inhibition of attentional bias after the initiation of active and sham tDCS | Using the E-prime software, RTs are recorded in milliseconds in the cognitive task assessing inhibition of attentional bias. The cognitive task lasts 5-6 minutes. RTs difference between the trials including gaming pictures and those including gaming pictures will be calculated and such RTs difference will be compared between the active and sham tDCS. | 45-47 minutes after the initiation of of active and sham tDCS | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Skin conductance responses (SCRs) in the ROC task after the initiation of active and sham tDCS | Using a biosignal recorder, SCRs are recorded in μs in the ROC task. This task lasts 12-13 minutes. SCRs in the downregulation condition will be compared between the active and sham tDCS. SCRs in the upregulation condition will also be compared between the active and sham tDCS. | 4 minutes after the initiation of active and sham tDCS | 
| Skin conductance responses (SCRs) in the ER task after the initiation of active and sham tDCS | Using a biosignal recorder, SCRs are recorded in μs in the ER task. This task lasts 12-13 minutes. SCRs in the downregulation condition will be compared between the active and sham tDCS. SCRs in the upregulation condition will also be compared between the active and sham tDCS. | 16-17 minutes after the initiation of active and sham tDCS ham tDCS | 
| Background craving before the initiation of active and sham tDCS | Using the Visual Analog Scale (from 1 = 'not at all' to 9 = 'very much'), background craving is assessed with a one-item questionaire (how much do you crave playing internet games now?). This assessment lasts approximately 1 minute. Background craving will be compared between the active and sham tDCS. | Approximately 10 minutes before the initiation of active and sham tDCS | 
| Cue-induced craving before the initiation of active and sham tDCS | Using the Visual Analog Scale (from 1 = 'not at all' to 9 = 'very much'), cue-induced craving is assessed in a cue-reactivity task. This assessment lasts 1-2 minutes. Cue-induced craving will be compared between the active and sham tDCS. | Approximately 8 minutes before the initiation of active and sham tDCS | 
| Background craving after the initiation of active and sham tDCS | Using the Visual Analog Scale (from 1 = 'not at all' to 9 = 'very much'), background craving is assessed with a one-item questionaire (how much do you crave playing internet games now?). This assessment lasts approximately 1 minute. Background craving will be compared between the active and sham tDCS. | 38-40 minutes after the the initiation of active and sham tDCS | 
| Cue-induced craving after the initiation of active and sham tDCS | Using the Visual Analog Scale (from 1 = 'not at all' to 9 = 'very much'), cue-induced craving is assessed in a cue-reactivity task. This assessment lasts 1-2 minutes. Cue-induced craving will be compared between the active and sham tDCS. | 40-42 minutes after the the initiation of active and sham tDCS |