Prevalence, correlates, comorbidity and severity of bipolar disorder: Results from the Singapore Mental Health Study

Abstract

Background

Bipolar disorder (BPD) is a serious mental disorder and a leading cause of premature mortality worldwide. Prevalence and risk factors of BPD have not been well studied in multi-ethnic Asian populations. The study aimed to establish the prevalence of BPD and examine the associated socio-demographic correlates, comorbidity, severity, impairment and treatment contact in the Singapore resident population.

Methods

The Singapore Mental Health Study was a cross-sectional epidemiological survey of a nationally representative sample of the resident (citizens and permanent residents) population in Singapore. The diagnoses were established using the World Mental Health Composite International Diagnostic Interview version 3.0 (CIDI 3.0) diagnostic modules for lifetime and 12-month prevalence of select mental illnesses including BPD.

Results

The lifetime and 12-month prevalence estimates for BPD were 1.2% and 0.6%, respectively. More than two-thirds (69.4%) of respondents with lifetime BPD had other lifetime mental disorders, and approximately half (52.6%) of respondents with lifetime BPD also had at least one chronic physical condition; chronic pain was the most prevalent comorbid condition.

Limitations

The data was based on respondents’ self-report and there could be an element of recall bias and under-reporting. We also did not obtain information on mixed episodes and rapid cycling disorders.

Conclusions

The high comorbidity, clinical severity, and role impairment associated with BPD exert a heavy toll at an individual and societal level.

Introduction

Bipolar disorder (BPD) is a serious mental disorder and a leading cause of premature mortality from suicide and associated comorbidity with medical disorders such as diabetes mellitus and cardiovascular diseases (Roshanaei-Moghaddam and Katon, 2009, Laursen et al., 2011, Chang et al., 2012) According to the Diagnostic and Statistical Manual of Mental Disorders fourth edition (DSM-IV) (American Psychiatric Association, 2000), the essential feature of bipolar I disorder (BP-I) is a clinical course that is characterized by the occurrence of one or more manic episodes or mixed episodes. Often individuals have also had one or more major depressive episodes (MDEs). In bipolar II disorder (BP-II), the clinical course is characterized by the occurrence of one or more major depressive episodes accompanied by at least one hypomanic episode. The recurrent nature of manic and depressive episodes often leads to high direct and indirect health care costs (Kleinman et al., 2003).

A recent study by Merikangas et al. (2011) reported the aggregate lifetime prevalence as 0.6% for BP-I and 0.4% for BP-II across eleven countries in the Americas, Europe and Asia as part of the World Mental Health Survey Initiative. Previous research has established that BPD is unrelated to gender (Merikangas et al., 2007, Lloyd et al., 2005) but some studies have reported that women are more likely to present with a depressive episode (Kennedy et al., 2005), and exhibit more depressive and less manic symptoms compared with men (Taylor and Abrams, 1981, Leibenluft, 1996). The findings for ethnic differences for BP-I incidence have been largely inconsistent (Lloyd et al., 2005, Kennedy et al., 2004, Shah et al., 2004). On the other hand, BPD is frequently comorbid with other mental disorders (Pini et al., 2005, Morgan et al., 2005) and this comorbidity in turn is associated with greater rates of disability, impairment, self-harm and suicide (Dalton et al., 2003, Moore et al., 2011).

There is little information on the rates, comorbidity and help-seeking patterns of BPDs in Asian populations. This paper reports findings of a population-based survey of the South-East Asian island nation of Singapore. Specifically, the study establishes the prevalence of BPD in the resident adult population and its rates among the different ethnic groups. It also examines the socio-demographic correlates, association with other chronic medical conditions; severity, impairment of role functioning and treatment contact among those with BPD.