I was answering the question on why Harry Potter wears glasses and I got to thinking about how the healing of physical injuries is discussed and debated fairly regularly, but mental illness is never addressed. Harry, Moaning Myrtle (before she died, presuming her personality was the same) and Cho Chang experience depression at one point or another in the series. Snape was an anxious kid/teen. Ariana Dumbledore had uncontrollable PTSD (for lack of a better description) There may be more examples that I'm not thinking of. ETA: The Dementors, of course! How could I forget about the Dementors? According to JK Rowling, Dementors are analogous to depression.
Is magical psychological treatment available in Potterverse? If so, what methods are used? How are persons with a mental illness treated in the Wizarding world?
ETA: 02.01.12 While researching another question, I found a spell that is used to treat mental illness in Potterverse. I'll leave this question open, to give the opportunity for someone to answer it.