FYI: Having watched my sister go through years of cancer treatment and eventually die, I can attest to the fact that it absolutely can attack the personality in ways much more devastating than bipolar actually. My husband also has bipolar disorder, but he also has diabetes, severe high blood pressure, and reflex sympathetic dystrophy. His doctors have found that much of his anxiety comes from the diabetes and blood pressure if they aren't managed, and much of his depression comes from the pain of the RSD. Physical illnesses can and do attack personality in very profound ways.