Transcranial Alternating Current Stimulation continues to be explored as a therapeutic option. Reading about the history of electrical stimulation of the brain, I came across this gem:
“Electric current from the chain was believed to be efficacious in applications to the head, and to stimulate mental performance. Samuel Patterson Evans, MD, Physician to the Newmarket-on-Fergus Dispensary, County Clare, Ireland, for instance, reported to PPulvermacher that it had successfully been used to restore mental energy. According to Evans, he advised one man who was not very strong intellectually, and whose mind became “tired and incapable of continued thought” after fatigue, to try the chain “applied round the head and forehead” on the basis that “the energy of the brain becomes exhausted, either from bodily labor or mental fatigue.” After undertaking the treatment, Evans believed that he had become “capable of more continued application in either thinking or writing since,” which he attributed to the fact that “the brain becomes stimulated by the outward dose of galvanic or electric energy supplied by the [Pulvermacher] Chain in action” which it had previously lost “either by its own loss of power directly, or indirectly by bodily fatigue.” Whilst warning that “its application in such cases should not be continued too long” in case the “constant and forced stimulation” caused serious injury to the brain, Evans believed that the application of the chain deserved to be “closely studied in relation to its action on the brains of intellectual individuals” and for all types of nervous condition (Pulvermacher, 1853, pp. 15, 16–17).”
A Medical Education 