I am 56 and what I notice is that my cycling is much more volatile now. It seems that as I get older this disease gets tougher to deal with, and it is depression and hypomania. I used to be able to easily define my mood swings, but now my hypomanic stages sometimes include paranoia and anger so that it is hard to ever find a peaceful time.
I have been on very many medication combinations, and I get very discouraged that I seem to grow more immune to the effects as I get older.
As for the depression question, I have at about the same amount throughout my 40's and 50's. It just an intensity problem for me.
Bluemountains