Bipolar[ism?] - Part I

["Bipolar" sounds weird, since it's used as the disorder, the person that has the disorder, and the state of having the disorder. ENGLISH IS WEIRD... not that other languages aren't.]

The other day, I was talking to a dear friend of mine [Let's call her "K"!] about bipolar. She's a type II bipolar; she offered a lot of insight on what it's like to actually be bipolar. She gave it a human face.
I had some prior knowledge, such as the basics of what the symptoms are, and that while its origin is shrouded in mystery, it is thought to be a result of some form of chemical or hormone imbalance. It is also relatively universal knowledge that bipolar is heavily based on genetics.
I asked a lot of questions, and she told me about the mood swings, the rapid cycling, the difficulties, the feeling of nothingness. [I even asked if me being so inquisitive was annoying, and she told me it wasn't: I was asking the "right" questions, and she knew I was especially interested in how it could apply to my "learnings".]
I was thinking about what she told me last night when I was in the shower, and a thought shouted, "How is bipolar related to the amygdala?" Another thought stemming from this asked, "How is bipolar related to puberty and, in girls, the menstrual cycle?"
K told me that she was a relatively normal child, and that her first mood shift/rapid cycle happened when she was twelve. I made a connection - to what we're learning at the moment - in that the average age of first menstruation [menarche] is 12.5. Could this mean that there's some correlation between onset of menstruation or puberty - with release of new hormones or upped amounts of old hormones? The hole in this is that bipolar also is diagnosed in children and adults, but still, it's an idea, isn't it?
I did a little research in Ceramics today and found that, in people suffering from bipolar, the amygdala are significantly smaller, volume-wise. The hippocampi are also somewhat smaller than those of their "regular", "normal" counterparts.
I also learned that womens' bipolar/mood cycles may fluctuate along with their menstrual cycle. Hmm.
I'll do more "investigation" over the weekend, and I'll discuss them here, in "Part II".