For a lot of depressed people, medication can significantly improve their life. This has been proven time and time again through double-blind clinical trials, just like any other medication that gets sold.

While for some people the medication becomes a permanent part of their lives, there are others it just helps get over an episode. Are they suffering from the same disease, just with a chronic vs episodic form? Are they in fact separate diseases? Are the drugs curing some people but only 'sustaining' others? I don't think we have the answers to these questions yet, but that doesn't mean that we don't have a wealth of evidence that these drugs can do more good than harm.