Hard to say for sure, because I have more issues than just BP.

But if I had to guess, I think I started cycling after I graduated from high school. I had always been very shy and introverted, with no social life, dressed very frumpy and identified as a nerdy sort of person.

But that first year after high school, I kept teetering between an irritable, panic-attack-loaded depression, and what in retrospect may have been hypomania or mania. I spent every penny I made at my job on all sorts of crazy, non-practical things, and I would morph into a social butterfly at random. Eventually it all merged into a terrible mixed state, and I couldn't function at all.