Epidemiology of Bipolar Disorder



1.    Prevalence

Lifetime Prevalence of Bipolar Disorders

Type of Bipolar Disorder
Total
Source
Bipolar I Disorder
0.4-1.6% (0.8%)
APA, 2000; (Kessler et al., 1994)
Bipolar II Disorder
0.5% (0.5%)
APA, 2000; (Kessler et al., 1994)
Cyclothymic Disorder
0.4 - 1.0%
APA, 2000
The DSM-IV-TR states that males and females have equal lifetime prevalence rates of Bipolar I Disorder and Cyclothymic Disorder; it is estimated that the lifetime prevalence rate of Bipolar II Disorder is slightly higher in females (APA, 2000).




2.    Culture  Features
            There are NO reports of race or ethicity-based differential incidence of Bipolar Disorder (APA, 2000).
 

3.    Age Features
            The American Psychiatric Association reports on their website the peak age of onset for Bipolar symptoms is between 15 and 19 years; this age range is closely followed by the range of 20-24 years.
 

4.    Familial Pattern

    The incidence of Bipolar Disorder is significantly high (11%) for patients whose First-Degree relatives have a history of Bipolar Disorder.  While researchers are still looking for a genetic link, the possibility exists that Bipolar Disorder is polygenetic (Rehm, Wagner, & Ivens-Tyndal, 2001).

    In twin studies, monozygotic twins have shown a 72%  concordance rate for Bipolar Disorders, while dizygotic twins have shown a 14% concordance rate (Rehm,  Wagner, & Ivens-Tyndal, 2001).  With such large concordance rates in monozygotic twins, Martin G. Allen, MD (1976) revealed the range in concordance rates to be between 20-96% for monozygotic twins in studies occurring between 1928 and 1974; the range of concordance rates for dizygotic twins is 0-38% (Allen, 1976).  The variability in range for both monozygotic and dizygotic twins can be attributed to sample size and criteria utilized in  the formulation the Bipolar Disorder Diagnosis.  The average concordance rate for monozygotic twins is around 55-60% and for dizygotic twins is 12-15%.  Rushton, Russell, and Wells (1985) report a concordance rate of 73% for monozygotic twins and 12% for dizygotic twins in patients with Bipolar Disorder.  Adoption studies have not yielded conclusive, replicable results.
 
 

5.    Comorbidity of Bipolar Disorders with Other Mental Illness

The following lifetime prevalence data were derived from a 2001 study involving 288 outpatients with Bipolar I or Bipolar II Disorder.  All prevalence data is the percentage of outpatients with comorbid Axis I disorders in the following categories: Substance Use Disorders, Anxiety Disorders, and Eating Disorders (McElroy, et al., 2001).
 
Comorbid Axis I Disorder
Bipolar I
Bipolar II
Substance Use Disorders
45
31
Alcohol
36
22
Stimulant
9
6
Sedative
10
2
Cocaine
10
4
Opiate
8
0
Marijuana
17
10
Hallucinogen
7
2
Anxiety Disorders
42
45
Panic Disorder w/ and w/o Agoraphobia
20
20
Social Phobia
17
12
Specific Phobia
11
8
Generalized Anxiety Disorder
3
2
Post Traumatic Stress Disorder
7
4
Obsessive Compulsive Disorder
9
10
Other Anxiety Disorders
3
4
Eating Disorders
5
12
Anorexia Nervosa
2
4
Bulimia Nervosa
3
6


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