I'm finding this quite interesting because that's what my doc told me and I didn't believe him and we had a huge argument.
I have no history of manic depression in my family but he said the death of my mom set it off and I should have sought out help much earlier than I did. I just thought I was depressed. He said it lies dormant and sometimes something happens that triggers it and it becomes active.
I guess I owe him a big apology.