“What do antidepressants do to the brain?”

Regulate neuroharmones,

The accepted answer to your question for many years was that antidepressants increased serotonin in the brain and in that way improved people's moods. Subsequently studies have shown that this theory about serotonin is not viable. Although it is not well publicized there is now clear evidence that these medications work by disrupting the connections between the feeling brain and the thinking brain so that the person does not feel as much. In almost all cases of depression, the depression is a sign that the person is not feeling that they have any real power in their life. You can learn much more about this subject by going online to a site called Mad in America or by reading the book by Robert Whitaker called Anatomy of an Epidemic.

They supply compounds that are deficient in the brain.