The Effects of tDCS on Depressive Symptoms,Neurocognitive Function and HRV in Unipolar Depression and Bipolar Depression
Condition: Depressive Disorder, Major; Depression, Bipolar; Electricity; Effects
MeSH terms: Depression; Depressive Disorder; Bipolar Disorder; Depressive Disorder, Major
Study type: Interventional

Summary: 
      The study aimed to investigate whether transcranial direct current stimulation could improve
      depressive symptoms, neurocognitive function and modulate heart rate variability in unipolar
      and bipolar depression.
    

Detailed description: 
      Background

      Transcranial direct current stimulation encompasses the induction of a relatively weak
      constant current flow through the cerebral cortex via scalp electrodes . Dependent on
      stimulation polarity, this results in a modulation of cortical excitability and spontaneous
      neural activity. The technique was established in the 1950s and 1960s primarily in animals.
      In these early studies it was shown that subthreshold DC stimulation increases spontaneous
      neuronal activity if the anode is placed above or within the cortex, while exposure to
      cathodal polarity results in reduced activity. This is caused by a subthreshold membrane
      depolarization by anodal and a hyperpolarization by cathodal stimulation. It was demonstrated
      in humans that the after-effects of tDCS depend on modifications of NMDA receptor-efficacy.
      The after-effects of tDCS are blocked by the NMDA receptor antagonist dextromethorphan, and
      prolonged by the partial NMDA receptor-agonist D-cycloserine. This tDCS polarity-dependent
      alteration of NMDA receptor function seems to be initiated by the respective membrane
      potential shift and probably by the accompanying cortical activity modification,because it is
      prevented by the sodium channel blocker carbamazepine. Intraneuronal calcium concentration
      also contributes, because calcium channel antagonists eliminate the excitability-enhancing
      after-effects of anodal tDCS. Recently, tDCS has been reported to be a novel, non-invasive
      and safe therapeutic tool to treat neuropsychiatric disorders including depression. This
      therapeutic tool has been reported to show promising effect in treating unipolar and bipolar
      depression. However, the sample sizes have been small. Further work is needed to see if these
      early promising studies replicate. Much evidence has indicated that patients with depression
      show hypoactivity over left dorsolateral prefrontal cortex (DLPFC) and hyperactivity over
      right DLPFC. We therefore hypothesize that tDCS over DLPFC with anode placed at left DLPFC
      and cathode placed at right DLPFC would reduce depressive symptoms in patients with unipolar
      depression and bipolar depression.

      The study aimed to investigate whether tDCS over DLPFC could modify depressive symptoms,
      neurocognitive function and heart rate variability of unipolar and bipolar depression.

      Study design: open-label study.

      Participants: 60 patients with unipolar depression and 60 with bipolar depression.

      Others: see Arms and Interventions, Eligibility Criteria or Outcome Measures.
    

Intervention name(s): tDCS over DLPFC
Intervention type(s): Device
Intervention description(s): We applied tDCS over dorsolateral prefrontal cortex (DLPFC) for these depressed patients. Direct current (DC) generated by a DC stimulator (Eldith DC stimulator: www. neuroconn.de/dc-stimulator_plus_en/) was bilaterally delivered through a pair of saline-soaked surface sponge electrodes (35 cm2). The anodal electrode was placed over the left dorsolateral prefrontal cortex (F3, International EEG System 10-20) and cathode electrode over F4. Stimulation was applied at an intensity of 2 mA for 20 min, twice-daily on 5 consecutive weekdays. The twice daily sessions were separated by at least 3 hours. All patients were maintained on their treatment throughout the study period.
Intervention model: Single Group Assignment
Intervention model description: Sixty patients with unipolar depression (major depressive disorder) and 60 with bipolar depression were treated with 10 sessions of tDCS.
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Unipolar depression; bipolar depression; Transcranial direct current stimulation