Testing would be nice.

I presume the testing would include more than just a Dx, though. That is, if testing could diagnose the condition, you'd probably be able to find other useful information such as how your individual brain chemicals change. (I mean, you'd probably have to know that information in order to make the diagnosis anyway.) Knowing individual brain chemistry would probably help us figure out which meds might work best, BP or not. Basically, genetic testing, only more accurate.

So in theory, it'd probably be super expensive! And I don't know how invasive it would be.

I actually think it's quite possible to do this already though, but the diagnosis process wouldn't be so practical. It's probably a matter of monitoring brain activity (neuron firing) and brain chemical changes on a daily basis waiting for a chemical imbalance to occur. So... brain monitoring for X many days in a row. Lotsa money