Bipolar disorder epidemiology

Bipolar disorders have been categorized into bipolar I disorder, bipolar II disorder, and bipolar disorder, not otherwise specified (NOS). Bipolar I disorder is characterized by one or more manic or mixed mood episodes. Bipolar II disorder is characterized by one or more major depressive episodes and at least one hypomanic episode. Hypomania is an abnormally and persistently elevated, expansive, or irritable mood, but not of sufficient severity to cause significant impairment in social or occupational function and does not require hospitalization. Most epidemiologic studies have looked at bipolar disorder of all types (bipolar I and bipolar II), or the bipolar spectrum, which includes all clinical conditions thought to be closely related to bipolar disorder. The lifetime prevalence of bipolar I disorder is estimated to be between 0.3% and 2.4%. The lifetime prevalence of bipolar II disorder ranges from 0.2% to 5%. When including the bipolar spectrum, the lifetime prevalence is between 3% and 6.5%.1... 

Weissman MM, Bland RC, Canino GJ, Faravelli C, Greenwald S, Hwu HG et al. Cross-national epidemiology of major depression and bipolar disorder. JAMA 1996 276 293-299. 

Believed historically to be a relatively rare disorder, large-scale epidemiological research undertaken during the last 20 years indicates that OCD is in fact quite common. The lifetime prevalence of OCD is 2-3%, making it more common, in fact, than bipolar disorder, schizophrenia, and most psychiatric illnesses other than depression and the substance use disorders. 

For more than 40 years, epidemiological studies have clearly demonstrated a tendency for diseases such as schizophrenia, bipolar disorder and autism... 

A number of epidemiological studies [including several reviewed in May and Lichterman 1993] have shown that panic disorder and unipolar depression occur more commonly together than could be explained by chance. Some 50%-70% of patients with panic disorder also have major depression [J. Johnson et al. 1990 Volrath and Angst 1989]. The association also holds true for seasonal depression [Halle and Dilsaver 1993] and to some extent for bipolar disorders [Savino et al. 1993]. 

To underscore the importance of adequate treatment for bipolar disorder, we note that it is estimated that one of every four or five untreated or inadequately treated patients commits suicide during the course of the illness, particularly during depressed or mixed episodes. Further, an increase in deaths secondary to accidents or intercurrent illnesses contributes to the greater mortality rate seen in this disorder in comparison with the general population. Unfortunately, recent epidemiological studies have indicated that only one third of bipolar patients are in active treatment despite the availability of effective therapies. 

Angst, J., Gamma, A., Benazzi, R, Ajdacic, V., Eich, D., Rossler, W. 2003, Toward a re-definition of subthreshold bipolarity epidemiology and proposed criteria for bipolar-II, minor bipolar disorders and hypomania, . Affect.Disord., vol. 73, no. 1-2, pp. 133-146. 

Obsessive-compulsive disorder (OCD) until recently was considered to be a very rare disorder. However, newer epidemiological studies show OCD to be just as common as panic disorder, and two to three times as common as schizophrenia or bipolar disorder. 

Bebbington P, Ramana R. The epidemiology of bipolar affective disorder. Social Pschiatry Psychiatr Epidemiol 1995 30 279-292. 

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