This type of neurotherapy was originally developed to help patients with brain injuries or neuropsychiatric conditions such as major depressive disorder.

[13] Recent research on tDCS has shown promising results in treating other mental health conditions such as anxiety[10] and PTSD.

[15] There is evidence of very low to moderate quality that tDCS can improve activities of daily living assessment in the short-term after stroke.

[17] According to the British National Institute for Health and Care Excellence (NICE), the evidence on tDCS for depression raises no major safety concerns.

The lasting modulation of cortical excitability produced by tDCS makes it an effective solution to facilitate rehabilitation and treat a range of neuropsychiatric disorders.

[26] The way that the stimulation changes brain function is either by causing the neuron’s resting membrane potential to depolarize or hyperpolarize.

When positive stimulation (anodal tDCS) is delivered, the current causes a depolarization of the resting membrane potential, which increases neuronal excitability and allows for more spontaneous cell firing.

When negative stimulation (cathodal tDCS) is delivered, the current causes a hyperpolarization of the resting membrane potential.

[21][27] In case of treating depression, tDCS currents specifically target the left side of dorsolateral prefrontal cortex (DLPFC) located in the frontal lobe.

Current is "conventionally" described as flowing from the positive anode, through the intervening conducting tissue, to the cathode, creating a circuit.

[32] After the stimulation has been started, the current will continue for the amount of time set on the device and then will automatically be shut off.

Recently a new approach has been introduced where instead of using two large pads, multiple (more than two) smaller sized gel electrodes are used to target specific cortical structures.

[31][33] In a pilot study, HD-tDCS was found to have greater and longer lasting motor cortex excitability changes than sponge tDCS.

Recently, tDCS devices are being researched and created intended for at-home use – ranging from treating medical conditions such as depression to enhancing general cognitive well-being.

[38] The basic design of tDCS, using direct current (DC) to stimulate the area of interest, has existed for over 100 years.

There were a number of rudimentary experiments completed before the 19th century using this technique that tested animal and human electricity.

Luigi Galvani and Alessandro Volta were two such researchers that utilized the technology of tDCS in their explorations of the source of animal cell electricity [citation needed].

In 1801, Giovanni Aldini (Galvani's nephew) started a study in which he successfully used the technique of direct current stimulation to improve the mood of melancholy patients.

Similar to tDCS, an increase or decrease in neuronal activity can be achieved using this technique, but the method of how this is induced is very different.

[6] In chronic pain following spinal cord injury, research is of high quality and has found tDCS to be ineffective.

[65] The cerebellum has been a focus of research, due to its high concentration of neurons, its location immediately below the skull, and its multiple reciprocal anatomical connections to motor and associative parts of the brain.

[67] While growing literature shows the efficacy of transcranial direct current stimulation (tDCS) for treating nervous diseases such as acute depressive episodes, the lack of knowledge about the nature of this treatment at the cell level[1] raises concerns regarding possible adverse effects that would appear long after the treatment has ended.

[68][69] While the therapeutic effect is observed in a short period of months, the impact of the electric fields on the brain, specifically on the treated neuronal structures, is a question of further long-term research.

[70] tDCS is a CE approved treatment for major depressive disorder (MDD) in the UK, EU, Australia, and Mexico.