Was put on antidepressants at 20 after having been low for years (from at least 15, but I remember my mum taking me to the doctors from about 13 with lethargy etc).
I was on them for a few months, enough to pick myself back up, and I have never gotten that low again.
BUT, every few months I will drop, I want to hide from the world, or my house (it varies, sometimes I just want to be alone, other times I want to be with people, but am shoddy company, or don't enjoy theirs), I get very tearful, lethargic, my house gets even worse than normal as I just can't see the point of doing it. It lasts for about a week, then I get just enough enthusiasm back to start to pull myself together and exercise etc (the various things that I know help lift me).
Since the ADs I have always managed to pick myself back up, but every time I drop, I worry that it is the start of something bigger.
Does it ever improve? I'm 24 now, and the thought of doing this little spiral for the rest of my life is disheartening to say the least!!!