Historical aspects of transcranial electric stimulation

The first clinical experience with electric fish, and a long history of application of electrotherapeutic techniques, started from the eighteenth century leading to the modern use of transcranial direct current stimulation (tDCS). This history had various degrees of success and the treatment of mental disorders using electricity followed a cyclical course throughout the centuries. In the beginning, clinicians approached transcranial electric stimulation with enthusiasm, treating numerous disorders such as neurasthenia, melancholia, mania, and hysteria, but also hallucinations, migraine, and dementia. This phase saw a lot of excesses and exaggerations, typical of early stages of the application of a new therapeutic technique. Later, at the end of the nineteenth century transcranial electric stimulation was considerably less used, After failing to produce consistent results. In the twentieth century, experimental data clearly demonstrated that using motor evoked potentials tDCS resulted in changes in motorcortical excitability supporting a series of new experimental clinical evidence. Today, tDCS is recognized as being an effective technique in applying a direct current to the scalp, further demonstrating its ability to treat clinical conditions such as affective disorders, chronic pain and postlesional cognitive disorders.