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A government commissioned survey of more than 61,000 patients suggests 2.4 percent of the world's population may have some form of the disease, which is marked by unexplained shifts in mood, energy and activity that can affect relationships and job performance.

Kathleen Merikangas of the National Institute of Mental Health in Bethesda, Maryland and colleagues wrote in the Archives of General Psychiatry, "It's very important that we understand the scope and magnitude of this disorder so that we can plan appropriate treatments, facilitate recognition of diseases, and identify people at risk so we can bring them into treatment ... Bipolar disorder is responsible for the loss of more disability-adjusted life-years than all forms of cancer or major neurologic conditions such as epilepsy and Alzheimer's disease, primarily because of its early onset and chronicity across the life span." The team conducted surveys of adults in the United States, Mexico, Brazil, Colombia, Bulgaria, Romania, China, India, Japan, Lebanon and New Zealand. The United States has the highest lifetime rate of bipolar disorder at 4.4%, and India the lowest, with 0.1%. Japan had a lifetime prevalence of 0.7%. Colombia, a lower-income nation, also deviated from the trend with a relatively high prevalence of 2.6%.

Results showed that less than half of those with bipolar disorder or manic-depressive psychosis received mental health treatment during their lifetimes. In low-income countries, only 25.2 percent of bipolar patients said they had any contact with the mental health system. Three fourths of those with bipolar disorder also met the diagnostic criteria for at least one other disorder, with anxiety disorders being the most common concomitant illness. Over 50% people said their symptoms started in adolescence, underscoring the need for early detection and treatment, the researchers said.

Mood disorders are among the most common diagnoses in psychiatry. Mood is a persistent emotional state (as differentiated from affect, which is the external display of feelings). There are three major categories of mood disorders according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition: unipolar mood disorders (major depressive disorder, dysthymic disorder), bipolar mood disorders (bipolar I disorder, bipolar II disorder, and cyclothymic disorder), and mood disorders having a known etiology (substance-induced mood disorder and mood disorder due to a general medical condition) (Table 2-1).

The best available evidence suggests that mood disorders lie on a continuum with normal mood. Although mania and depression are often viewed as opposite ends of the mood spectrum, they can occur simultaneously in a single individual within a brief period, giving rise to the concept of mixed mood states.

Mood disorders are characterized by a disturbance in the regulation of mood, behavior, and affect. Mood disorders are subdivided into (1) depressive disorders, (2) bipolar disorders, and (3) depression in association with medical illness or alcohol and substance abuse. Depressive disorders are differentiated from bipolar disorders by the absence of a manic or hypomanic episode. The relationship between pure depressive syndromes and bipolar disorders is not well understood; depression is more frequent in families of bipolar individuals, but the reverse is not true. In the Global Burden of Disease Study conducted by the World Health Organization, unipolar major depression ranked fourth among all diseases in terms of disability-adjusted life years and was projected to rank second by year 2020. In the United States, lost productivity directly related to depression has been estimated at $44 billion per year.

References

National Institutes of Health, National Institute of Mental Health. (n.d.). Statistics: Any Disorder Among Adults. Retrieved March 5, 2013, from http://www.nimh.nih.gov/statistics/1ANYDIS_ADULT.shtml

National Institutes of Health, National Institute of Mental Health. (n.d.). Any Disorder Among Children. Retrieved March 5, 2013, from http://www.nimh.nih.gov/statistics/1ANYDIS_CHILD.shtml

National Institutes of Health, National Institute of Mental Health. (n.d.) The Numbers Count: Mental Disorders in America. Retrieved March 5, 2013, from http://www.nimh.nih.gov/health/publications/the-numbers-count-mental-disorders-in-america/index.shtml

Prevalence numbers were calculated using NIMH percentages (cited) and 2010 Census data. Census data is available at: United States Census Bureau. (revised 2011). "USA [State & County QuickFacts]." Retrieved March 5, 2013, from http://quickfacts.census.gov/qfd/states/00000.html