The Effects of Bimodal tDCS on Illness Severity, Insight, Functional Outcomes, Neurocognition and HRV in Schizophrenia
Condition: Schizophrenia; Insight Impaired; Psychotic Symptoms; Schizoaffective Disorder; Neurocognitive Dysfunction; Autonomic Imbalance; Psychosocial Impairment; Quality of Life
MeSH terms: Schizophrenia; Psychotic Disorders; Cognitive Dysfunction
Study type: Interventional

Summary: 
      The study aimed to investigate the effects of bimodal anodal transcranial direct current
      stimulation (tDCS) over bilateral dorsolateral prefrontal cortex (DLPFC) on
      psychopathological symptoms, insight, psychosocial functioning, neurocognitive function and
      heart rate variability (HRV) in schizophrenia patients
    

Detailed description: 
      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 N-methyl-D-aspartate
      (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,
      unimodal anodal tDCS over left dorsolateral prefrontal cortex (DLPFC) has been found to
      improve psychopathological symptoms, cognitive deficits and insight of schizophrenia and also
      strengthen cardiac autonomic function in healthy subjects. Further studies using bimodal
      anodal tDCS over bilateral dorsolateral prefrontal cortex (DLPFC) and prefrontal cortex are
      needed.

      Study design: randomized double-blind, sham-controlled study design.

      Participants: 60 patients having a diagnosis of schizophrenia or schizoaffective were
      randomly allocated to receive 20 minutes of active 2-mA tDCS or sham stimulation twice a day
      on 5 consecutive weekdays. These participants were assessed at baseline, after intervention
      and in a three-months follow-up.

      Active or sham stimulation: The present study used bimodal anodal tDCS over bilateral
      dorsolateral prefrontal cortex (DLPFC) and prefrontal cortex. One anode was placed with the
      middle of the electrode over a point midway between International 10-20 electrode positions
      F3 and Fp1 (left dorsolateral prefrontal cortex and left prefrontal cortex). The other was
      located over a point midway between F4 and Fp2 (right dorsolateral prefrontal cortex and left
      prefrontal cortex). An extracephalic positions were used for the reference electrodes
      (cathodes) in order to avoid confounding effects from inhibitory cathodal effects at other
      cortical sites. The reference electrodes were placed on bilateral forearms.

      Others: see Arms and Interventions, Eligibility Criteria or Outcome Measures.
    

Intervention name(s): tDCS
Intervention type(s): Device
Intervention description(s): tDCS
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Direct current (DC) generated by a Eldith DC stimulator was bilaterally delivered through a pair of saline-soaked surface sponge electrodes (35 square centimeter). One anode was placed with the middle of the electrode over a point midway between International 10-20 electrode positions F3 and Fp1 (left dorsolateral prefrontal cortex and left prefrontal cortex). The other was located over a point midway between F4 and Fp2 (right dorsolateral prefrontal cortex and left prefrontal cortex). An extracephalic positions were used for the reference electrodes (cathodes) in order to avoid confounding effects from inhibitory cathodal effects at other cortical sites. The reference electrodes were placed on bilateral forearms. Stimulation was applied at an intensity of 2 milliampere (mA) (current density=1.14 A/square meter) for 20 min, twice-daily on 5 consecutive weekdays (total charge density=2736 C/square meter).
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Treatment