I once saw this subject being discussed on Snet and but I did not join the discussion. One of the reason why I did not join was because I did not want to speak about something I knew little about. However, I did believe in depression and that muslims can get depressed but what about PRACTISING ones? Well I stumbled upon this lecture discussing exactly that! And what a refreshing subject too. I'm tired of muslims who don't believe in mental-illness, depression or even jiins (which at this point becomes an aqeedah issue). The fact that they always believe mental illness is from something 'bad' a person did! No, it can be GENETICS too!
The Sheikh even spoke about "drinking the ayats of the quran after having written it and washed it off," and you know what? It is Sunnah!
Allah the Almighty said; “And We send down, of the Quran, that which is a healing and a mercy to the believers.” (Israa/82)
وننزل من القرآن ما هو شفاء ورحمة للمؤمنين) الإسراء 82
At one point he recites a story (authenticity is doubted) about a great king, that sent the Prophet muhammed (pbuh) a physician as a gift, and he pbuh said, "we don't need a physician, we don't eat much!"

Anywho listen to it on youtube:
Depression, Mental illness and Possession
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p.s. The panel of speakers vary as well. One is a introductory sheikh, the other sheikh deals with possession, and a doctor to speak about the depression and mental-illness! I forgot the last one though. Lol