A recent article in a recognized peer reviewed journal, the American Journal of Psychiatry, discussed the growing acceptance of a new model of bipolar staging in which early findings before and during adolescence predicted onset of first episode of bipolar mania by young adulthood.  They offer a diagram for the readers consideration, which I will copy below.

So, one can note a detail about lithium nonresponders having a different trajectory–disease–than lithium responders (i.e. they have ADHD, LD, schizoaffective disorder) and hence would likely do better with second gen. antipsychotics, etc.