unit 7 epidemiology bipolar disorder

The Epidemiology of Bipolar Disorder

Lifetime Prevalence of Bipolar Disorder by Age

Total (%)

18-29 (%)

30-44 (%)

45-59 (%)

60+

Bipolar I-II disorders 3.9 5.9 4.5 3.5 1.0

Source: Kessler RC et al. Lifetime prevalence and age-of-onset distributions of DSM-IV disorders in the National Comorbidity Survey Replication. Arch Gen Psychiatry 62:593-602.

Based on the National Comorbidity Survey Replication (NCS-R) – the most recent nationally representative survey

Earlier studies (NCS; Epidemiologic Catchment Area [ECA]) found slightly lower lifetime prevalence rates (~1%)

Population-based studies in 10 different countries have found consistent lifetime prevalence rates of bipolar disorder (0.3 to 1.5%)

Twelve-Month Prevalence of Bipolar Disorder by Severity

Total (%)

Serious (% of all cases)

Moderate (% of all cases)

Mild (% of all

cases)

Bipolar I-II disorders 2.6 82.9 17.1 0.0

Source: Kessler RC et al. Lifetime prevalence and age-of-onset distributions of DSM-IV disorders in the National Comorbidity Survey Replication. Arch Gen Psychiatry 62:593-602.

Incidence and Age of Onset (AOO)

Average age of onset: 25 years oldRange: 12 to 65+

First-episode mania cases in the elderly may be associated with comorbid cerebrovascular disorder

Source: National Institute of Mental Health.

Source: Tohen M, Angst J. Epidemiology of Bipolar Disorder. In: Textbook in Psychiatric Epidemiology, MT Tsuang and M Tohen, eds. (2nd edition). Wiley-Liss, 2002: New York.

Annual Incidence

Data from the U.S. are limitedScandinavian countries:

9.2 to 15.2 per 100,000 men 7.4 to 32.5 per 100,000 women

England and Denmark: 2.6 per 100,000 individuals

Ireland: 4.5 per 100,000

Sources: National Institute of Mental Health

Bipolar II

Bipolar II has been less studied than Bipolar ILifetime prevalence estimates of 0.2% to

0.9% may underestimate bipolar II, because hypomania is not always recognized

Comorbid Conditions

Substance abuse (~60.7% prevalence among those with Bipolar I in the ECA study)

Anxiety disorders

Source: Tohen M, Angst J. Epidemiology of Bipolar Disorder. In: Textbook in Psychiatric Epidemiology, MT Tsuang and M Tohen, eds. (2nd edition). Wiley-Liss, 2002: New York.

Risk Factors (1)

More common in urban than rural populationsHigher prevalence in institutionalized (prisons,

nursing homes) and homelessNo apparent gender differenceAssociation of bipolar disorder with class status is

unclear Some studies suggest higher prevalence in higher

socioeconomic classes, but may be due to assessment bias – those with lower socioeconomic status may be more likely classified as schizophrenic or psychotic

ECA program found higher rates in those with less education

Source: Tohen M, Angst J. Epidemiology of Bipolar Disorder. In: Textbook in Psychiatric Epidemiology, MT Tsuang and M Tohen, eds. (2nd edition). Wiley-Liss, 2002: New York.

Risk Factors (2)

Race ECA program and other studies found no

differences by race

Marital status Those cohabiting, divorced, or never married more

likely to suffer from bipolar disorder than married individuals

Family history of bipolar disease

Source: Tohen M, Angst J. Epidemiology of Bipolar Disorder. In: Textbook in Psychiatric Epidemiology, MT Tsuang and M Tohen, eds. (2nd edition). Wiley-Liss, 2002: New York.

Age, Sex, and Ethnicity

The Epidemiologic Catchment Area (ECA) Program – the first study in the U.S. that obtained prevalence rates for bipolar disorder using structured diagnostic instruments – found that lifetime prevalence varied by age group, but not by sex or ethnic group

Source: Tohen M, Angst J. Epidemiology of Bipolar Disorder. In: Textbook in Psychiatric Epidemiology, MT Tsuang and M Tohen, eds. (2nd edition). Wiley-Liss, 2002: New York.