A Functional Magnetic Resonance Imaging Investigation of Transcranial Direct Current Stimulation
Condition: Anxiety State
Study type: Interventional

Summary: 
      This study evaluates the effect of frontal cortex transcranial direct current stimulation
      (tDCS) on the neural correlates of threat processing in healthy volunteers with a high level
      of trait anxiety. All participants received both active and sham tDCS and underwent a
      functional imaging scan whilst carrying out an attentional control task with fearful
      distractors.
    

Detailed description: 
      There is a growing body of evidence suggesting that repeated administration of prefrontal
      transcranial direct current stimulation (tDCS) is a potential effective treatment for
      depression through restoring a left/right imbalance in frontal brain activity (Boggio et al.,
      2008; Loo et al., 2012) and improving top down control of anxiety responses.

      An initial exploratory study was carried out in 2012 (Ironside et al 2015) to examine the
      effects of tDCS on emotional processing in healthy volunteers using a range of tasks and
      questionnaires. Using a dot probe task, which measures attention to happy or fearful faces,
      it was found that tDCS has the potential ability to reverse an attentional bias to fearful
      faces seen in the placebo group. This indicates that anxiety responses may be modified using
      tDCS and therefore this follow on study seeks to further explore the role of tDCS in trait
      anxiety and investigate the neural correlates of this with fMRI.

      The present study uses behavioural and neuroimaging results to examine how tDCS affects
      emotional processing relevant to trait anxiety. A within-subjects design increases the power
      of the study, given limited resources to carry out extensive neuroimaging. Our working
      hypothesis is that tDCS may alter activity in cortical regions relevant to attentional
      control and anxiety.

      The findings of this study will be used to determine parameters for future patient studies,
      involving participants with generalized anxiety disorder or major depression. The ultimate
      aim, explored through further studies, is to understand and improve how tDCS might be used in
      the treatment of these disorders.
    

Intervention name(s): transcranial direct current stimulation
Intervention type(s): Other
Intervention description(s): Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulatory technique that uses weak electrical current to increase (with anodal) or decrease (with cathodal) the probability of brain activity in the stimulated region. This typically has acute effects relating to cortical activity levels which last up to one hour.
This intervention delivers 20 minutes of 2mA bipolar balanced tDCS, with anodal tDCS delivered to the left dorsolateral prefrontal cortex (DLPFC) and simultaneously cathodal tDCS delivered to the right DLPFC. In the sham condition 40 seconds of stimulation is delivered.
Other intervention name(s): tDCS
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Placebo controlled crossover design
Masking: Single (Outcomes Assessor)
Primary purpose: Other