Transcranial direct current stimulation

It is the use of direct electrical currents to stimulate specific areas in the brain. The process is painless and does not need any surgery. The electrodes are placed on the head, and the low-frequency current is passed to change the neuronal activity (Elsner et al., 2017).

Here are the pros and cons of the transcranial direct current stimulation (tDCS):

Pros:

  • It improves the learning process of the brain. The cognitive function is also enhanced.  The primary motor cortex significantly enhances the motor skill task if it is stimulated by tDCS.
  • The driving abilities improve after stimulating the dorsolateral prefrontal cortex.
  • The cortical regions such as the primary and secondary somatosensory cortex and anterior cingulate cortex are linked with pain perception. Therefore, tDCS is also used to treat some chronic pain conditions which are unresponsive to any other medication or medication used to have serious side effects such as fibromyalgia – in this condition, opioids are used, which cause severe side effects (K, 2012).
  • The language learning skills are improved when the left frontal lobe of the brain is stimulated.
  • The two-week therapy is helpful in patients suffering from depression. The stimulation in the left dorsolateral prefrontal cortex increases the cortical function and helps in depression.
  • It is used to improve sleep quality by increasing the time of the deep and profound phases of sleep. For this reason, it is used in post-polio syndrome to improve quality of the sleep.
  • In attention-deficit/hyperactivity disorder, tDCS is helpful to focus selectively and increase attention.
  • The stimulation of the motor cortex of the brain can be helpful in patients with stroke (Elsner et al., 2017). The stroke-induced aphasia is corrected by tDCS.
  • The working memory and cognitive functions are significantly improved by stimulating the dorsolateral prefrontal cortex (DLPFC) region by tDCS. The excitability of this region increases the performance.  
  • It also enhances visual attention.

Cons

  • Mild tingling, burning, and itching sensation is felt at the point of the electrode. The transcranial direct current stimulation-induced erythema can alter the binding and intensity of the electrodes.
  • Headache and nausea occur due to stimulation of the chemoreceptor trigger zone in the brain by the current.
  • Some patients have insomnia due to changes in cortical stimulation.
  • Regular use of the electrodes causes transcranial direct current stimulation-induced erythema, which can be severe. The erythema is reduced by pretreating the skin with ketoprofen, hydroxyzine, and lidocaine.
  • The direct current is affected by the media present in ways such as hair that can play the role of an insulator. Therefore, the use of saline water is needed.
  • The current is also affected by sweat. The sweat is a conductor due to which the current intensity changes.
  • The transcranial direct current stimulation is also reported to change some complex behavior such as impulsivity.

Transcranial direct current stimulation and hypnosis in treating depression

Several studies show that in the treatment of depression, transcranial direct current stimulation is very effective in treating depression (Moffa et al., 2020). In transcranial direct current stimulation, a direct current of 1-2 mA is applied, which may cause alteration in the cortical excitability. The effects last for a few hours, and the continuous stimulation causes changes in the synaptic connections. The therapeutic effect of the stimulation in depression is achieved through the release of neurotransmitters. However, the exact efficacy of the tDCS is still not understood, and further investigation is required. Another prevalent method to treat depression is the use of hypnosis (Rosa & Lisanby, 2012). While patients are remaining in the hypnotic state, they target the unnecessary and unhealthy habits and learn to control them (Hypnotherapy and Depression: How It Works, n.d.). During hypnosis, the connection between the dorsolateral prefrontal cortex and insula increases. This does not involve any medications and devices, while in tDCS, electrodes are used to stimulate the mentioned area.

References

Elsner, B., Kwakkel, G., Kugler, J., & Mehrholz, J. (2017). Transcranial direct current stimulation (tDCS) for improving capacity in activities and arm function after stroke: a network meta-analysis of randomised controlled trials. Journal of NeuroEngineering and Rehabilitation, 14(1), 95. https://doi.org/10.1186/s12984-017-0301-7

Hypnotherapy and Depression: How it Works. (n.d.). Retrieved October 30, 2021, from https://www.healthline.com/health/depression/hypnotherapy

K, L. (2012). Transcranial direct current stimulation for the reduction of clinical and experimentally induced pain: a systematic review and meta-analysis. Clin J Pain, 28(5), 452–461. https://doi.org/10.1097/AJP.0b013e31823853e3

Moffa, A. H., Martin, D., Alonzo, A., Bennabi, D., Blumberger, D. M., Benseñor, I. M., Daskalakis, Z., Fregni, F., Haffen, E., Lisanby, S. H., & Padberg, F. (2020). Efficacy and acceptability of transcranial direct current stimulation (tDCS) for major depressive disorder: An individual patient data meta-analysis. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 99, 109836. https://doi.org/10.1016/j.pnpbp.2019.109836

Rosa, M., & Lisanby, S. (2012). Somatic treatments for mood disorders. Neuropsychopharmacology, 37(1), 102–116. https://doi.org/10.1038/npp.2011.225