A few months ago I heard a story on National Public Radio about a professor who was showing that a carefully placed "brain pacemaker" can have some miraculous curing effects for those with previously insurmountable depression. One of those who received the implant described the feeling he had when it was first turned on: "I felt a feeling of wellness".
Nevertheless, a similar method previously used for epilepsy has now been
approved by the FDA, despite questionable effectiveness:
Cyberonics began a 200-patient study to see whether VNS could treat depression patients not adequately helped by other therapies. An FDA review last year found no difference after three months of implant treatment. Cyberonics argued that a year later, a significant number of the VNS recipients had had their depression ease.
Placebo? All I know is that if I had crippling depression I'd probably feel a lot better with a hole in my head and a wire hanging out of it giving my brain electric shocks, whether or not it had any physiological effect or not. Wires in my head just gives me the warm fuzzies all around.