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International Impact of Bipolar Disorder Highlights Need for Recognition and Better Treatment Availability

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Science Update

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The severity and impact of bipolar disorder and bipolar-like symptoms are similar across international boundaries, according to a study partially funded by NIMH. The results were published in the March 2011 issue of the Archives of General Psychiatry.

Background

Although several studies report prevalence rates of mental disorders on an international level, the numbers have varied because each study tends to use different methodology and definitions. To remedy this, the World Health Organization’s World Mental Health (WMH) survey initiative used consistent data collection methods in 11 countries in the Americas, Europe, Asia, the Middle East and New Zealand. The survey also applied common diagnostic definitions for mental disorders found in the Diagnostic and Statistical Manual for Mental Disorders (DSM-IV).

NIMH researcher Kathleen Merikangas, Ph.D., and colleagues used WMH data to track prevalence rates of three subtypes of bipolar spectrum disorder—bipolar I, bipolar II and bipolar disorder not otherwise specified (BD-NOS). Bipolar I disorder is considered the classic form of the illness, in which a person experiences recurrent episodes of mania and depression. People with bipolar II disorder experience a milder form of mania called hypomania that alternates with depressive episodes. People with BD-NOS, sometimes called subthreshold bipolar disorder, have manic and depressive symptoms as well, but they do not meet strict criteria for any specific type of bipolar disorder noted in the DSM-IV. Yet, BD-NOS can significantly impair those who have it.

Results of the Study

The prevalence rates of bipolar I, bipolar II and BD-NOS were 0.6 percent, 0.4 percent, and 1.4 percent, respectively, with an overall bipolar spectrum rate of 2.4 percent. The United States had the highest prevalence rate of bipolar spectrum (4.4 percent), while India had the lowest rate (0.1 percent). More than half of those with bipolar disorder in adulthood note that their illness began in their adolescent years.

Across all countries studied, 75 percent of those who had bipolar symptoms met criteria for having at least one other disorder. Anxiety disorders, especially panic disorder, were the most common coexisting disorders, followed by behavior disorders and substance use disorders. Patterns of coexisting conditions were similar across countries.

Less than half of those with bipolar symptoms received mental health treatment. In low income countries, only 25 percent reported having contact with a mental health professional.

Significance

This study provides the first international prevalence data on bipolar disorder using reliable, standardized methodology. It highlights the international impact of bipolar disorder and the need for better recognition and treatment availability. The findings also support the notion that, given its multi-dimensional nature, bipolar disorder may be better characterized as a spectrum disorder.

In addition, because so many people note that their illness began in adolescence — a critical time of life for educational, occupational and social development — early detection, intervention, and possibly prevention of subsequent coexisting disorders and complications should be emphasized.

What’s Next

More research is needed to better define the thresholds and boundaries of bipolar symptoms. In addition, further research is needed to better understand why and how the disorder tends to originate in adolescence and persist into adulthood, and how it intersects with coexisting mental disorders.

Reference

Merikangas KR, Jin R, He J, Kessler RC, Lee S, Sampson NA, Viana MC, Andrade LH, Hu C, Karam EG, Mora MEM, Browne MO, Ono Y, Posada-Villa J, Sagar R, Zarkov Z. Prevalence and correlates of bipolar spectrum disorder in the World Mental Health Survey Initiative. Archives of General Psychiatry. March 2011. 68(3):241-251.