Dinah's post about the new movie, The Changeling, generated some discussion about ECT in the comments (Angelina Jolie's character got electroconvulsive therapy in 1928, nine years before the first published description), started by Romeo Vitelli who asked, "Did they have ECT in 1928? I was under the impression that it was first developed in Europe in the 1930s."
Electroconvulsive shock therapy was discovered by Ugo Cerletti and Lucio Bini in Rome, in 1937.
Source: The History of Shock Therapy in Psychiatry
Apparently insulin-induced coma was all the rage in the late 20s.
And didn't Francis Farmer (and a whole bunch of other people) get an ice-pick lobotomy from a psychiatrist in the 1950s?
Psychiatrists of yore performed some pretty barbaric treatments on their patients.
It seems the movie took some liberties with "the truth," though. No surprise there.
Anon is right about 1937 being the first description, though it must have occurred earlier for them to write about it. But other types of "shock" treatments were used before electricity (as in "a shock to the system").
Insulin shock treatment was first described in 1934 by Manfred Sakel, according to my 1948 third edition of Samuel Kraines' The Therapy of the Neuroses and Psychoses. Insulin was used to induce a "therapeutic coma," usually daily for 15-30 days and lasting 30-60 minutes. Occasionally, the coma resulted in a convulsion, and it was found that these convulsions resulted in improvement, spawning many different "treatment" pathways to achieve these therapeutic convulsions.
Kraines (p487): "There may be convulsions present during the coma; but contrary to Sakel's fears, these convulsions are usually found to be beneficial to the patient. Indeed, some authors give metrazol or use electric shock for patients who are in insulin coma." (p493): "... [other] agents include ... picrotoxin, coriamytrin, azoman, ammonium chloride, camphor, methylguanidine and others."
Metrazol was first introduced by von Meduna in 1935 for schizophrenia, the same year that Moniz and Lima from Portugal described prefrontal lobotomies.
I haven't seen the movie yet, but I guess they must have wanted it to be in 1928 (because of stock market crash?), so they took artistic license on when ECT began.