Bipolar disorder is characterized by unusually large fluctuations in mood such that a person experiences recurrent episodes of depressed mood and episodes of being in an abnormally “elevated, expansive or irritable” mood according to the Diagnostic and Statistical Manual 4th ed. of the American Psychiatric Society (DSM-IV, 1994). Bipolar disorder was previously known as manic-depressive illness.
Before describing the diagnostic features of bipolar disorder, it is necessary to understand that the elevated mood mentioned in the definition above is classified into two subtypes; manic, and hypomanic.
The DSM-IV states that a hypomanic episode is distinguished from a manic episode in that hypomania is not so severe as mania and does not lead to “marked impairment in social or occupational functioning or requiring hospitalization”.
Hence the symptoms exhibited in mania and hypomania are similar varying only in degree or intensity and may include:
Fluctuations in mood between mania and severe depression have been known for over 2000 years, having been written about by Hippocrates.
The Greek physician Aretaeus, in the second century AD, was one of the first to suggest that there was some kind of relationship between melancholia (depression) and the apparently opposite emotional state of mania.
Modern day clinicians on the basis of their observations of bipolar patients, have also proposed explanations of this relationship.
Mania is observed to be accompanied by an extremely low frustration tolerance level and when frustrated, the manic patient will sometimes lose his manic good humour and becomes angry or burst into tears. This suggests that the mania is an attempt to cover up painful emotions.
Another observation supporting this hypothesis is that it is not unusual for persons without bipolar disorder to become involved in a flurry of trivial activity after a stressor e.g. manic-like housecleaning, to avoid facing painful emotions due to loss of a spouse.
This again suggests that the manic response may be a way to escape underlying emotions such as anger or depression. However there is at present little scientific evidence to support this hypothesis.
In the DSM-IV, the bipolar disorders are divided into two kinds: Bipolar 1 and Bipolar 2.
The essential feature of Bipolar I is a clinical course that is characterized by “one or more Manic Episodes. ... Often individuals have also had one or more Major Depressive Episodes..”. The DSM-IV gives a rather complicated set of criteria for Bipolar I with six major subtypes.
The essential feature of Bipolar II disorder is the occurrence of one or more major depressive episodes accompanied by at least one hypomanic episode.
One study found that in bipolar I disorder, depression is three times more common than mania while another study found that in bipolar II, depression was up to 39 times more common than the time spent in hypomania.
For this reason bipolar II is sometimes mistakenly diagnosed as recurrent major depression.
Summarizing, the main difference between Bipolar I and Bipolar II disorder is that in Bipolar I there is at least one episode of full blown mania whereas in Bipolar II there is only hypomania.
Features frequently found in bipolar disorder are:
The mood swings in bipolar disorder I disorder are by definition severe enough to cause significant problems in everyday functioning.
For example, a person experiencing a manic episode may go out and buy a condominium on impulse even though it will cause them financial ruin.
Sole et al (2011) have reviewed the relevant literature and concluded that there is increased risk that persons with bipolar II disorder have cognitive impairment including “working memory and some measures of executive functions (inhibitory control)” and verbal memory impairment.
The lifetime prevalence for bipolar disorder was found to be 3.9% (combined bipolar I and II) in a large US epidemiological study (Kessler 2005) making it the second most prevalent mood disorder being outranked by major depressive disorder with a lifetime prevalence of 16.6%.
There is much evidence that bipolar disorder as defined in the DSM-IV is too narrow and it would be more accurate to have a broader more inclusive concept called “bipolar spectrum disorders”.
Bipolar spectrum disorders would include not just Bipolar I and II but also a new condition called subthreshold bipolar disorder: defined as “recurrent hypomania without a major depressive episode or with fewer symptoms than required for threshold hypomania” (Merikangas et al, 2007).
Using this definition, and the same National Comorbidity Survey Replication sample of 9282 persons in the US as was used by Kessler et al in 2005, Merikangas et al found lifetime prevalence for bipolar I to be 1.0%, bipolar II to be 1.1%, and subthreshold bipolar disorder to be 2.4%.
Thus the total lifetime prevalence for bipolar spectrum disorders combined would be 4.5%, while the 12 month prevalence was 2.8%.
They also found that as expected “Clinical severity and role impairment are greater for threshold than for subthreshold bipolar disorder...” but perhaps surprisingly that “subthreshold cases still have moderate to severe clinical severity and role impairment”.
They conclude that subthreshold bipolar disorder, is definitely clinically significant, is more common than bipolar I and II combined, and therefore more mental health resources should be devoted to its detection and treatment.
A more recent study based on a review of published research on the prevalence of bipolar disorder included “a wide spectrum of bipolar disorders”. It concluded that the prevalence of bipolar spectrum disorders for 6/12 months was just .843% (Ferrari, Baxter, & Whiteford, 2011).
This is much lower than the 2.8% obtain for similar prevalence by Merikangas et al and possible reasons for the discrepancy were presented by the authors.
Standard treatments include:
A relatively new, and likely very important approach, to the treatment of bipolar disorder has been discussed by MacNeil et al (2012). It is based on the observation that medical conditions and likely psychiatric conditions pass through identifiable stages e.g. stage 0 involves only risk factors, stage 1 featuring prodromal symptoms, etc up to stage 4 characterized by persisting symptoms.
It has been proposed that these stages may have a neurobiological basis involving the concepts of neuroprogession and neurosensitisation. Most important is the idea that selection of treatment should depend on what stage of the disease process the client is in. It may also be that intervention at early stages may be more effective than at later stages.
A recent prospective study found that 19.6% of a sample of persons with major depressive disorder, followed for a mean of 17.5 years, developed hypomania or mania and consequently were diagnosed as having bipolar disorder (Fiedorowicz et al, 2011).
In view of this progression from major depression to bipolarity, the stage approach would seem very applicable. For example although lithium may be effective at later stages, it may be that different pharmacological agents or indeed non-pharmacological approaches could be more effective at earlier stages of bipolar disorder.
American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders. (4th ed.) Washington, DC: Author.
Eppel, A. (2010). Antidepressant Use in Bipolar Disorder: Continuing an Age-Old Debate. The American Journal of Psychiatry, VOL. 167, (11), 1408-1408.
Ferrari, A. J., Baxter, A. J., & Whiteford, H. A. (2011). A systematic review of the global distribution and availability of prevalence data for bipolar disorder. Journal of Affective Disorders, 134(1-3), 1-13.
Fiedorowicz, J. G., Endicott, J., Leon, A. C., Solomon, D. A., Keller, M. B., & Coryell, W. H. (2011). Subthreshold hypomanic symptoms in progression from unipolar major depression to bipolar disorder. The American Journal of Psychiatry, 168(1), 40-48.
Gregory, V. L., Jr. (2011). Cognitive-behavioral therapy for comorbid bipolar and substance use disorders: A systematic review of controlled trials. Mental Health and Substance Use, 4(4), 302-313.
Macneil, C. A, Hallam, K., Conus, P., Henry, L., Kader, L., & Berk, M. (2012). Are we missing opportunities for early intervention in bipolar disorder? Expert Review of Neurotherapeutics, 12(1), 5-7.
Merikangas, K. R., Akiskal, H. S., Angst, J., Greenberg, P. E., Hirschfeld, R. M. A., Petukhova, M., & Kessler, R. C. (2007). Lifetime and 12-month prevalence of bipolar spectrum disorder in the National Comorbidity Survey Replication. Archives of General Psychiatry, 64(5), 543-552.
Schöttle, D., Huber, C. G., Bock, T., & Meyer, T. D. (2011). Psychotherapy for bipolar disorder: A review of the most recent studies. Current Opinion in Psychiatry, 24(6), 549-555.
Solé, B., Martínez-Arán, A., Torrent, C., Bonnin, C. M., Reinares, M., Popovic, D., . . . Vieta, E. (2011). Are bipolar II patients cognitively impaired? A systematic review. Psychological Medicine: A Journal of Research in Psychiatry and the Allied Sciences, 41(9), 1791-1803.