Hey man, late to the party, so you can see by the replies of the others that many people know this.
But I wouldn't say that it's necessarily depression. Here's my story:
I made music since I was 8, really got into it with about 13 and was actually on a path to fame when I was about 18. I loved the time, I had a few bands, made music everyday, shat on schoolwork, the only thing I wanted to do was music. And we became pretty good, well known in our area and even made it into a big radio station. I thought about doing this for the rest of my life.
Then one day, the flame just went out. From 100 to 0, I just didn't feel like it anymore. I was really good at my craft and I kept on practicing for the bands, but I wouldn't pick the guitar up just like that anymore. Not that I burned out, it was no stress ever, but the love was just fading away.
Then a few things changed. Bandmembers moved to different cities for college, one threw me out because of dumb resons, one broke up because of drug abuse and so on. So I haven't had any more reson to make music. And I completely stopped. I did something else. The years have passed. I sometimes noodled around a little, to see if I'm still able to play.
And one day I met this girl and I fell in love with her. Back was the flame, fresh like a breeze in spring. Then I realized it. Making music was my expression of love. I started making music when I had my first crush with 13, kept on, got better, met other girls. Then with about 19, I had a Single time. No more music.
Today I'm making music every day again. Not on a level like earlier, but just for fun, just for myself. I don't have any intention of getting famous anymore, but let's see where the path leads.