The classification of the different types of bipolar disorder has been an issue of debate for some time. Increasingly, in some parts of the world there has been a move to the development of more categories or subtypes of bipolar disorder. Bipolar III, for example, has been defined to mean where a person experiences a hypomanic or manic switch after receiving an antidepressant. The principal types (bipolar I and bipolar II) may be separate sub-types or differ merely dimensionally (e.g. by severity or duration), with the term 'bipolar spectrum' assuming dimensional differences.
Why making the distinction is important come down to the implications for treatment. In bipolar I disorder, the mood stabilisers (especially the gold standard, lithium) are considered to be the mainstay of treatment. The role of the mood stabilisers in bipolar II disorder is less clear and up for debate, especially as new antidepressants and atypical antipsychotics have come on the market. There is an increasing interest in this area and more trials are currently underway (see the Black Dog Institute's Bipolar II Study). These will hopefully clarify whether each condition should be similarly treated.
Bipolar I disorder is defined as being present if the person experiences one or more lifetime episodes of mania and usually episodes of depression. The severity and duration of episodes are often severe and may result in hospitalisation.
Bipolar II disorder is defined as being present if the person experiences episodes of both hypomania and depression but no manic episodes. The severity of the highs does not lead to hospitalisation.
What separates normal 'happiness' from the euphoria or elevation, which is seen in mania and hypomania? Research at the Black Dog Institute has identified six principal features that appear to make this distinction. These features are:
Read more about these six features
As noted, in mania, these experiences are more extreme and severe. Mystical experiences can reach delusional intensity with the development of other psychotic symptoms. The high levels of energy reach manic excitement; the patient is unable to sleep, thoughts and speech are so fast as to be unintelligible. Inappropriate behaviour can place the individual or others at risk, especially if associated with intense irritability and delusional beliefs (e.g. persecutory delusions that someone is after them, or grandiose delusions that they have the power of flight).
The depression experienced by sufferers of bipolar disorder is equally severe for people with bipolar I as for people with bipolar II. Some recent studies have reported that depression can be both more frequent and more chronic in the case of people with bipolar II than with bipolar I. There has also been found to be a comparable suicide risk between the two subtypes.
Thus, definitional differences are not always associated with clear functional differences.
Page last updated: 27-Jan-2009
Depression and Bipolar Disorder Information Australia - Black Dog Institute.
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