The idea that some sort of convulsive shock seemed to clear up mental disturbances isn't new; even Hippocrates noted that convulsions caused by malaria seemed to help patients with mental illness. The idea that electric shock could be used to clear up mental disturbances was actually based on a false idea -- that epileptics were less likely to suffer from schizophrenic symptoms [source: Encyclopædia Britannica]. In one of those strange twists of science, however, epileptic-type convulsions did seem to affect mood.
By the 20th century, psychiatrists were experimenting with insulin-shock therapy, where large doses of insulin were injected into a patient to bring on an hour-long or so coma [source: Encyclopædia Britannica]. The insulin would then be flushed from the system with a salt solution, and voila -- schizophrenic patients would recover. OK, they didn't always recover. But enough to make scientists explore the phenomenon more.
In 1938, two Italian scientists pioneered using electric shocks to jolt a man with delusions. After a few treatments, the delusions receded. By the 1940s, ECT was being used in the United States to treat depression, bipolar disorder and schizophrenia. But it's important to remember how different the early versions of ECT were compared to the more modern practice.
First off, early ECT didn't involve anesthesia. That means, of course, that a patient was aware of what was happening, which was very traumatic. No modern muscle relaxants were administered, so there was a big risk for the body to shake and jerk violently -- so much so that fractures would occur. The electric current was also higher than is used in modern practice, so the seizures were violent. The procedure also caused more extreme memory loss in patients, which is probably why popular culture portrayed it as leaving patients zombie-like and lobotomized.