There are significant differences between these two forms of bipolar disorder. The information below is taken mostly from the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (or DSM-IV). It should be noted that possible major changes are proposed for the upcoming fifth edition; however, some of the important proposed changes as currently written conflict with each other, and thus I am relying on the fourth edition at this time.
Note: Because the terms bipolar I and II are used interchangeably with bipolar 1 and 2 (bipolar II is even often mistyped as bipolar 11!), I have used those terms interchangeably in this article.
Here's a summary of the most important differences between bipolar I and II.
A person with bipolar I has manic episodes, while someone with bipolar II has hypomanic episodesThe main difference between mania and hypomania is a matter of severity. In the hypomania of bipolar 2, a person has a sustained mood that is elevated (heightened), expansive (grand, superior) or irritable. This mood has to be noticeably different from his or her normal mood when not depressed. In mania, that mood is abnormally different, and is also combined with increased activity or energy that is also abnormal.
For example, Hank, when he has hypomanic episodes, is exceptionally cheerful, needs only three hours sleep instead of his usual seven, spends more money than he safely should and speaks far more rapidly than usual, along with other symptoms of hypomania. This behavior is noticeably different from his own stable mood, yet there are cheerful people who need little sleep, spend a lot and talk fast who don't have bipolar disorder, so it's not considered abnormal.
On the other hand, Hank's friend Robert, who has manic episodes, is out-of-control happy, even during serious events (he burst out laughing disruptively during a funeral). He ran around outside at midnight shouting how much he loved all his neighbors (along with other symptoms of mania). This is abnormal behavior for anyone.
Other differences between bipolar I mania and bipolar II hypomaniaOne or more of the following conditions has to exist in mania but can't be present in hypomania:
- Mania may include psychotic symptoms - delusions or hallucinations. Hypomania does not have psychotic symptoms.
Robert firmly believes he is the mayor of his town and introduces himself to people as such, telling them about grandiose and sometimes bizarre plans he has for making improvements to services and infrastructure. If Hank had a similar delusion, his diagnosis would be bipolar I rather than bipolar II. The presence of psychosis automatically rules out hypomania.
- While hypomania may interfere to a degree with daily functioning, in mania day-to-day life is significantly impaired.
Robert missed an important business meeting because of a spur-of-the-moment decision to take flying lessons. Hank may be longing to take flying lessons while hypomanic, but if he does, he takes them at a reasonable time when he has no other obligations.
- The manic person has to be put in the hospital because of the severity of symptoms.
During an irritable manic episode, Robert began throwing crockery, silverware, pots and pans at his wife because he wasn't satisfied with that night's dinner. He was subsequently hospitalized because he had become a danger to others. Hank's hypomania does not escalate to such an extreme extent.