That's actually a permanent problem that only rears its head when the shit hits the fan. If the triggering stress was applied consistently the mental illness would be ongoing.
I think that says more about the nature of psychosis brought on by extreme stress than it does about the patient. The article says genetics can be a factor, but for this diagnosis in particular calling it a permanent attribute of the sufferer seems misguided. It seems naive to think that most of us wouldn't completely break down with the right amount of stress, maybe varying amounts for different people.