Empire of Pain: The Secret History of the Sackler Family by Patrick Radden Keefe:
The favored treatment at Creedmoor during this period was a procedure that was not as invasive but that Arthur nevertheless disdained: electroshock therapy. The treatment had been invented some years earlier by an Italian psychiatrist who arrived at the idea after a visit to a slaughterhouse. Observing how pigs were stunned with a jolt of electricity just before they were killed, he devised a procedure in which electrodes were placed on the temples of a human patient so that a current of electricity could be administered to the temporal lobe and other regions of the brain where memory is processed. The shock caused the patient to convulse, then lapse into unconsciousness. When she came to, she was often disoriented and nauseous. Some patients experienced memory loss. Others felt profoundly shaken after the procedure and did not know who they were. But for all of its blunt force, electroshock therapy did seem to offer relief to many patients. It appeared to alleviate intense depression and to soothe people who were experiencing psychotic episodes; it might not have been a cure for schizophrenia, but it could often mitigate the symptoms.
Nobody understood why exactly this treatment might work. They just knew that it did. And at a place like Creedmoor, that was enough. The therapy was first used in the hospital in 1942 and was eventually administered to thousands of patients. To be sure, there were side effects. The convulsions that patients experienced as the electric charge pulsed through their heads were painful and deeply frightening. The poet Sylvia Plath, who was administered electroshock treatment at a hospital in Massachusetts during this period, described how it felt as if “a great jolt drubbed me till I thought my bones would break and the sap fly out of me like a split plant.” The singer Lou Reed, who received electroshock treatment at Creedmoor in 1959, was temporarily debilitated by the ordeal, which left him, in the words of his sister, “stupor-like” and unable to walk.