Bipolar disorder is actually a spectrum of mood disorders which can be categorised according to the types and severity of episodes the person experiences. Hypomania, mania and depression are described in my post “What is bipolar disorder?“. The types of bipolar disorder and the types of episodes the person experiences are:
Bipolar I disorder (BD-I)
- History of at least one episode of mania.
- May or may not experience depressive episodes.
Bipolar II disorder (BD-II)
- One or more episodes of hypomania (mild mania).
- One or more episodes of depression.
- No history of full manic episodes (otherwise qualifies for BP-I).
Bipolar I and II disorders are very similar but in BP-II, the mania (called hypomania) is milder than in BP-I.
Although BP-II used to be described as less severe than BP-I, this is no longer thought to be the case since people with BP-II spend such a large part of their lives in depressive episodes.
- For at least two years (1 year in children and adolescents) symptoms of hypomania or depression have been present but do not meet the full episode criteria.
- In a 2 year period, the symptoms need to have been present at least half of the time
Cyclothymia is basically a mild, chronic form of bipolar disorder.
Bipolar disorder not otherwise specified (NOS)
This category is for people who meet some of the criteria for bipolar disorder but not enough for a diagnosis under one of the categories above.
- Short duration episodes of hypomania (the person experiences symptoms of hypomania but they last only a few days) and depression.
- Hypomania but no history of depressive episodes.
- Short duration cyclothymia but for less than 2 years (the symptoms have to be present most days and the person must not have been symptom free for any more than 2 months at a time).
Major depressive disorder (MDD)
- Two or more episodes of depression.
- No history of mania or hypomania.
In the current, 5th edition of the Diagnostic and Statistical Manual (DSM-V) for psychiatrists, the “with seasonal pattern” specifier has replaced Seasonal Affective Disorder (SAD).
In the current, 5th edition of the Diagnostic and Statistical Manual (DSM-V) for psychiatrists, Seasonal Affective Disorder (SAD) is no longer recognised as a distinct disorder but as a subset of bipolar or major depressive disorder. People with bipolar or depression disorders might receive a specifier “with seasonal pattern” if their episodes frequently occur at a particular time of year. For example, people might routinely experience mania or hypomania in spring and depression in winter.
The person experiences four or more episodes in a 12-month period. Rapid cycling is associated with a worse course of illness and is more difficult to treat.
The person experiences simultaneous symptoms from mood episodes of both depression and mania/hypomania. For example, the person may be experiencing all the symptoms of depression but have restless energy and rapid thoughts. Suicide risk is particularly high in mixed states.