Im thinking obsession is a symptom of mental illness.
Probably. Anythings possible :D
I obsess about going mad, is that the same thing?
Obsession can sometimes be described as dedication. But yes I guess your right but it depends on what your obsessed with you could say I'm obsessed with movies or your obsessed with drawing but that won't cause any illness
I think certain mental illness bring on obsessive behavior
I don't know. I am obsessive, but I move around a lot- it's the best way for me to stock all my info.
I thought obsession WAS considered a mental illness, or at least an emotional one
well, being obsessed with anything, is definitely not a good thing; I'm not sure that it always leads to a mental illness, but to the extreme, I suppose it can.