A friend and I were having this discussion about the differences between Bipolar I and II, and I had to revert to my trusty pocket version of the DSM to remind myself.
Bipolar I is the most extreme of the disorders. In order to receive a diagnosis of Bipolar I the individual must have at least one manic episode. MANIC is the key term here- HYPOMANIC is not the same.
Hypomania can have symptoms of rapid speaking, racing ideas, not sleeping, and surges of energy. Individuals who are hypomanic are usually able to keep up with their social and occupational obligations.
Mania is intense and often frightening. Individuals may lose touch with reality, believing they are a deity, on a mission from a deity (delusions of grandeur), or experience a psychotic break. They may fly into rages. They may engage in dangerous and destructive behaviors such as abusing stimulants (cocaine, speed) or reckless driving. They may spend money with abandon and may ruin their financial lives in a matter of days.
A mixed episode is when mania and the depressive state are happening at the same time. Just thinking about this occurring is a nightmare for me. Visualize a person in a very foul, depressed, hopeless mood and combine it with racing thoughts and raging energy. Mixed episodes have symptoms such as panic, paranoid delusions, suicidal ideation, and rage.
Ok, so back to Bipolar I and II.
Bipolar I must have had at least one manic episode. A depressive episode is not needed for the diagnosis, but will usually be present at least once.
Bipolar II must have had at least one hypomanic episode and one depressive episode.
Cyclothymia could be seen as Bipolar II Lite. There must be hypomanic episodes and depressive episodes, but the depressive episodes do not need to be as severe as they are for Bipolar II.