Types of bipolar

Bipolar I disorder

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. 

Bipolar II disorder

If you have one hypomanic and one major depressive episode then you could have type II. Type II isn't a milder form of the disorder. Hypomanic episodes are less sever however people with this type seem to experience more major depressive episodes in their lives.

Cyclothymia

It is milder than bipolar. People can experience hypomanic and depressive episodes. It is chronic and can last at least two years.

Mixed episodes

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.

Rapid-cycling bipolar

People can experience at least four manic and depressive episodes (even both) in one year.

Environmental forms of bipolar

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).