If you have one manic episode especially when you experience psychosis (where you lose touch of reality) then you could have type I. It can be followed by a hypomanic or major depressive episode.
It is milder than bipolar. People can experience hypomanic and depressive episodes. It is chronic and can last at least two years.
This happens when manic and depressive episodes happen at the same time. People are energised and can be impulsive or do risky things. They also feel hopeless, helpless and worthless while being depressed.
People can experience at least four manic and depressive episodes (even both) in one year.
Medical conditions such as multiple sclerosis, Cushing's disease or a stroke can cause signs of bipolar disorder, circumstantial (medical interactions - like antidepressants that can trigger mania - major life changes and severe stress are other risk factors) and psychological (having another psychological disorder).