Bipolar II disorder is similar to bipolar I, with moods cycling between high and low over time. However, in bipolar II disorder, the “up” moods never reach full-blown mania. These less-intense elevated moods in bipolar II disorder are called hypomanic episodes, or hypomania. A person affected by bipolar II disorder has had at least one hypomanic episode in their life. Most people with bipolar II disorder suffer more often from episodes of depression. In between bouts of hypomania and depression, many people with bipolar II disorder live normal lives.
I’m struck by how many times I see people who have been diagnosed with bipolar II disorder saying something along the lines of – “At least I have the mildest version of it.” While the hypomania associated with bipolar II is less destabilizing than the mania seen in bipolar I, it doesn’t make bipolar II easier to cope with. Sometimes it can be just the opposite.
Despite the significant differences in duration and severity between a manic and hypomanic episode, bipolar II disorder is not a “milder form” of the disorder. When compared against individuals with bipolar I disorder, individuals with bipolar II disorder have greater chronicity of illness. They also spend more time on average in the depressive phase of their illness, which can be severe and/or disabling.
In order to receive a diagnosis of bipolar I, a person must have experienced at least one episode of mania, but no depression needs to be present. According to the American Psychiatric Association, it is necessary to meet the criteria for a current or past hypomanic episode and a major depressive episode for a diagnosis of bipolar II. Likewise, the symptoms of depression or the unpredictability caused by repeated alternation between periods of depression and hypomania can result in clinically significant distress or impairment in social, occupational, or other important areas of functioning (American Psychiatric Association, 2013, pp. 132-5).
A major depressive episode must last two weeks or more, and a hypomanic episode must last at least four days to meet the diagnostic criteria. During the mood episode(s), the necessary number of symptoms must be present most of the day, almost every day, and represent a noticeable change from usual behavior and functioning. In a hypomanic episode, the disturbance in mood and the change in functioning is observable by others.
Depressive symptoms co-occurring with a hypomanic episode or hypomanic symptoms co-occurring with a depressive episode are common in individuals with bipolar II disorder and are overrepresented in females, particularly hypomania with mixed features.
While many individuals with bipolar disorder return to a fully functional level between episodes, roughly 30% show severe impairment in work role function.
Suicide Risk is Exceptionally High in Bipolar II Disorder
The lifetime risk of suicide in individuals with bipolar disorder is at least 15 times higher than that of the general population. According to the American Psychiatric Association, bipolar disorder may account for one-quarter of all completed suicides (2013, p. 131).
Approximately one-third of individuals with bipolar II disorder report a lifetime history of suicide attempts.
While the prevalence rates of lifetime attempted suicide in bipolar I and bipolar II appear to be similar (32.4% and 36.3%, respectively), the lethality of attempts, as defined by a lower ratio of attempts to completed suicides, is higher in individuals with bipolar II disorder (American Psychological Association, 2013, p. 138).
There may also be an association between genetic markers and increased risk for suicidal behavior in individuals with bipolar disorder, including a 6.5-fold higher risk of suicide among first-degree relatives of bipolar II probands compared with those with bipolar I disorder. The risk of bipolar II disorder tends to be highest among relatives of individuals with bipolar II disorder compared to bipolar I disorder or major depressive disorder.
Bipolar II and Increased Incidence of Co-Morbidities
Bipolar II disorder is more often than not associated with one or more co-occurring mental disorders. Approximately 60% of individuals with bipolar II disorder have three or more co-occurring mental disorders. One in three has a substance use disorder, and three in four have an anxiety disorder (American Psychological Association, 2013, p. 139).
Bipolar II may not be an easier road to travel than other forms of the disorder. In terms of basic symptom acuity, this may be true. But when we ask whether bipolar I or bipolar II is more easily managed by those with the disorder, the answer is less than clear.
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American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders, 5th Edition: DSM-5 (5th ed.). American Psychiatric Publishing.