Until recently, I have been guilty of assuming just this. However after I was diagnosed with bipolar II in May this year and my feverish efforts to read as much as I can about bipolar in general, as well as the specifics of bipolar II, I believe that there was an error in my thoughts. It seems the scientific community (which is where I got my information from) is also guilty of making such claims (1).
Perhaps one of the main reasons for previous thoughts is the difference in the diagnostic criteria between the two disorders.
Firstly, for a diagnosis of bipolar II you must have experienced both a hypomanic and a depressed episode. Forbipolar I, only the presence of a manic episode is required (however depressed episodes may also occur) (2).
Secondly, and most interestingly, it is the criteria that distinguishes a hypomanic episode from a manic episode that provides the main distinction between the two disorders. The types of behaviours for either kind of episode are identical; the difference lies in the severity. In mania:
[t]he mood disturbance is sufficiently severe to cause marked impairment in occupational functioning or in usual social activities or relationships with others, or to necessitate hospitalization to prevent harm to self or others, or there are psychotic features" (2, p.362).
Hypomania in comparison:
"is not severe enough to cause marked impairment in social or occupational functioning, or to necessitate hospitalization, and there are no psychotic features" (2, p.368).
Diagnostic criteria such as this does little other than suggest that bipolar II is the poor cousin of bipolar I by focusing on the severity of (hypo)manias.
Furthermore, most research into bipolar disorder does not differentiate between the two disorders (1), and usually includes people with either diagnosis in their research programs. Therefore, because the two are rarely investigated individually, any differences between the disorders have remained hidden. Of the research that does distinguish between the two, a larger focus falls on bipolar I (3). I believe this may, at least in-part, be due to the fact that mania is predominantly more visible thanhypomania or depression and is often portrayed by the media as being associated with violence. This of course is unfounded.
In recent times, however, some researchers have disagreed with the aforementioned premise, and have begun to treat bipolar I and II as distinct and separate disorders (1). Additionally, it appears that a significant proportion of people with treatment-resistant depression may in-fact have bipolar II (4). As a result of such investigations, evidence is emerging to suggest that bipolar II is just as serious an illness as bipolar I.
Research suggests that the severity of illness associated with bipolar 1 is acute and lasts for shorter periods compared to the severe symptoms of bipolar II which tend to be chronic (5). Overall, people with bipolar II spend more time in episodes of illness than do those with bipolar I, contributing to a higher morbidity rate and decreased functioning (4). Most of this time is spent in depressive episodes(6), which are frequently more severe than hypomanic or even manic episodes (5). Furthermore, the depression tends to be more severe and last for longer periods in those diagnosed with bipolar II than bipolar I (4, 7). This does not always involve the same symptoms as major depressive disorder (although it may), and often symptoms associated with 'atypical depression' are present such as excessive sleep, and weight gain (4).
Perhaps because of such chronicity, those with bipolar II are less likely to obtain functional recovery between episodes than those with bipolar I. Functional recovery is defined as a return to the occupational and residential status one had before the episode began (8). Bipolar II is also associated with a greater impairment in quality of life and an increase in lifestyle disruptions than those with bipolar I (9).
Mortality statistics also lend credence to the theory that bipolar II is not a soft form on bipolar I. Some figures suggest that the rate of attempted suicides is the same between the two types of bipolar, while others have found that bipolar II may have a higher prevalence (10). However, given that 80% of all suicides occur during a depressed episode (11), and the presence of a depressive phase is a robust predictor of attempts (12) it would not be surprising for an increased rate in those with bipolar II, as by definition, those with the disorder must have experienced depression, whereas this is not a requirement for bipolar I.
Finally, there is always going to be individual differences between each person with a given disorder, and these always need to be given careful consideration, rather than treating the disorder instead of the person.This, I suspect, is more important than any diagnosis.
1. Vieta, E., Gasto, C., Otero, A., Nieto, E., & Vallejo, J. (1997). Differential features between bipolar I and bipolar II disorder. Comprehensive Psychiatry, 38, 98-101.
2. American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed, text revision). Washington, DC: Author.
3. Judd, L. L., Akiskal, H. S., Schettler, P. J., Endicott, J., Leon, A. C., Solomon, D.A., Coryell, W.,et al. (2005). Psychosocial disability in the course of bipolar I and II disorders: a prospective, comparative, longitudinal study. Archives of General Psychiatry, 62, 1322-1330.
4. Berk, M., & Dodd, S. (2005). Bipolar II disorder: a review. Bipolar Disorders, 7, 11-21.
5. Judd, L. L., Akiskal, H. S., Schettler, P. J., Coryell, W., Maser, J., Rice, J. A., et al. (2003). The comparative clinical phenotype and long term longitudinal episode course of bipolar I and II: a clinical spectrum or distinct disorders? Journal of Affective Disorders, 73, 19-32.
6. Merikangas, K. R., Akiskal, H. S., Angst, J., Greenberg, P. E., Hirschfeld, R. M. A., Petukhova, M., et al. (2007). Lifetime and 12-month prevalence of bipolar spectrum disorder in the NationalComorbidity Survey replication. Archives of General Psychiatry, 64, 543-552.
7. Mantere, O., Suominen, K., Valtonen, H. M., Arvilommi, P., Leppamaki, S., Melartin, T., et al. (2008). Differences in outcome of DSM-IV bipolar I and II disorders. Bipolar Disorders, 10, 413-425.
8. Wingo, A. P., Baldessarini, R. J., Holtzheimer, P. E., & Harvey, P. D. (2010). Factors associated with functional recovery in bipolar disorder patients. Bipolar Disorders, 12, 319-326.
9. Robb, J. C., Cooke, R. G., Devins, G. M., Young, L. T., Joffe, R. T. (1997). Quality of life and lifestyle disruption in euthymic bipolar disorder. Journal of Psychiatric Research, 31, 509-517.
10. Baldessarini, R. J., & Tondo, L. (2003) Suicide risk and treatments for patients with bipolar disorder. Journal of the American Medical Association, 290, 1517-1519.
11. Royal Australian and New Zealand College of Psychiatrists Clinical Practice Guidelines Team for Bipolar Disorder (2004). Australian and New Zealand clinical practice guidelines for the treatment of bipolar disorder. Australian and New Zealand Journal of Psychiatry, 38, 280-305.
12. Valtonen, H. M., Suominen, K., Mantere, O., Leppamaki, S., Arvilommi, P., & Isometsa, E. T. (2006). Prospective study of risk factors for attempted suicide among patients with bipolar disorder.Bipolar Disorders, 8, 576-585.
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