To me.. 'developmental' infers that something 'happened' during early development (in the womb). This could be a random genetic mutation at conception or some causative factor influenced by the environment. My impression is that bipolar disorder is genetic and inheritable. This, to me, doesn't mean developmental. Can the disorder be cause by environmental influences during development? I'm not sure about that??

My dad has bipolar.. and lots of other 'issues' within my siblings.. alcohol, drug addiction, etc. My dad, however, didn't have issues with addiction. But he definitely went through cycles of major depression and hypomania. And I'm starting to wonder about my mom too now that I know more about this...