In my own experience I spent 6 years undergoing both psychiatric,psychotherapist and abuse treatment...I had to ask why they kept labeling me as bipolar rapid cycler with PTSD..They said that considering that I've lost literally years of my life due to abusive episodes I've blocked I had PTSD tacked on to the episodes of bipolarism.
I must say that even after 10 years being diagnosed,my family still does not understand the extent to which my mind and body are affected,plus if you throw menopause into the mix...How do you get people who still believe that these episodes are truly my fault and not truly a mental illness(I hate that label) to understand that it isn't something I can just turn on and off at will.
I've spent a great deal of my life trying to figure out why I was different(sudden rages,on top of the world,and the major portion of my earliest memories not something I ever felt were real)so if you want my opinion and the opinion of 2 of the psychotherapists who treated me;abuse can be a major factor in starting the whole bipolar process.