Both of these aren't exactly what you're looking for, but they are excellent fics:

Pro Re Nata (http://teashopmuses.livejournal.com/10682.html) - Depression isn't always angst and sadness. Sometimes it's anger and dismissal and even humor. Dean's had clinical depression for years. Sam and Castiel find out.
Subterranean Homesick Blues (http://break-kitkat.livejournal.com/8915.html) - Fill for a prompt: Unknown to Sam, Dean has been reliant on anti-anxiety medication since he got back from Hell. [...] One day he wakes up to find that Sam has thrown out all his pills, painkillers, tranqs and booze: he's decided it's time for his brother to sober up. Dean tries to warn him how bad things will get, but Sam still isn't prepared for what happens.

Thank you!