I've been depressed for 18 years (still are)... in my opinion, you can't fully cure it, but you can help ease the emotional disturbance. People can think they're fully cured, but it only takes a small problem to trigger back the depression.

The key here is to find out the cause. Each person with depression has a reason that caused them this depression.. and get support and love from people around them. Those who do show they have depression often WANT to be helped, because they WANT people to know they're depressed. It's those who don't show it is the dangerous one.. they hide it so well until one day when they snapped, then it's too late.