Effects of Repetitive tDCS on ad Libitum Smoking Behavior: EMA and EEG Study
Condition: Addiction
MeSH terms: Behavior, Addictive
Study type: Interventional

Summary: 
      Bilateral (left cathodal/ right anodal) transcranial Direct Current Stimulation (tDCS) over
      the dorsolateral prefrontal cortex (DLPFC) seems to reduce craving and to increase the time
      till smoking the first cigarette after the intervention. The current study explores whether
      actual cigarette consumption decreases after repetitive tDCS. Cigarette consumption and
      craving will therefore be measured by means of EMA, before (at baseline), during and after
      multiple tDCS sessions, and at 3 months follow-up.

      To study the working mechanism behind the effects of tDCS, electrophysiological responses
      (ERPs) and behavioral measures of cognitive control functioning will be taken into account at
      baseline, one day after the last tDCS session and at three months follow up.

      We hypothesize that cigarette consumption will decrease after repetitive tDCS, and that this
      effect is associated with better cognitive control functioning.
    

Detailed description: 
      The proposed experiment is a double-blind randomized placebo-controlled trial. 60 smokers
      will be randomly assigned to two conditions, namely tDCS or sham (placebo).

      Participants will receive real tDCS or sham for three days in one week. The interventions
      contain twice daily sessions for 13 minutes with an interval of 20 min. Moreover, on the
      first treatment day and the day after the treatment week, participants complete a number of
      questionnaires, and perform two psychological tasks (a gambling task and the Go/NoGo task) to
      measure cognitive control functioning (e.g. risky decision making and inhibitory control
      respectively). During these tasks, event-related potentials will be recorded by means of EEG.
      After three months, participants are asked to return to fill out the same questionnaires and
      perform the same psychological tasks as before, to measure the lasting effect of tDCS. During
      this last session, event-related potentials will also be recorded. In addition, carbon
      monoxide levels will be measured on all days where subjects perform the tasks.

      EMA:

      For three weeks, starting the week before tDCS treatment, participants are asked to log every
      cigarette before they smoke one. During these weeks, participants complete EMA questionnaires
      on their mobile phone about cigarette consumption, craving, and affect that will take
      approximately 5 minutes. The EMA questionnaire will be presented four times daily on a
      quasi-random basis. Finally, during end-of-day assessments participants have the possibility
      to indicate any missed cigarettes. At three months follow-up, participants are asked to
      undergo the same EMA procedure for one more week, to study the lasting effects of tDCS.
    

Intervention name(s): tDCS
Intervention type(s): Device
Intervention description(s): tDCS is an electrical brain stimulation method
Other intervention name(s): transcranial direct current stimulation
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Treatment
Keywords: Smoking; EMA; ERPs; tDCS; Cigarette consumption; Inhibitory control; Reward processing; Tobacco addiction; Craving; electrophysiological