I have Bipolar 1. In my case, it is referred to as either a fragile or brittle form of the disease.
Being fragile has nothing to do with toughness or being delicate. It’s to do with how quickly you cycle, the fact that doing the right things won’t ‘fix’ you to the extent that it will fix someone not fragile/delicate etc.
Put simply: despite being fully compliant with treatment and meds, I rapid cycle, end up in hospital etc and I can’t pick when I’m next going to have an episode.