What is the Epidemiology of Bipolar Disorder?

Bipolar disorder is a relatively common psychiatric disorder. Bipolar I has a lifetime prevalence of 0.4% to 1.6% (i.e., at any given time, 0.4% to 1.6% of the population has the illness). Bipolar II has a lifetime prevalence of approximately 0.5%. Bipolar I is equally common in men and women, while bipolar II is more common in women. It appears that women are at a particular risk for depressive and intermixed mood symptoms. In addition, women with bipolar I or II disease may be at increased risk of developing subsequent episodes during the postpartum period.

Some important features of bipolar disorder include:

  • affected people may experience psychotic symptoms – Based on a review of studies, it is estimated that approximately two-thirds of individuals with bipolar disorder have a lifetime history of at least one psychotic symptom.
  • people with bipolar disorder have a high rate of suicide – Completed suicide occurs in as many as 10% to 15% of people with bipolar disorder. Studies show that 25% to 50% attempt suicide at least once, while an even higher percentage may experience suicidal ideation. This is more likely to occur during a depressive or mixed state.
  • people with bipolar disorder often have comorbid psychiatric disorders, including alcohol or drug abuse – Increased alcohol consumption is more frequently associated with manic phases. In contrast, the use of stimulants, such as cocaine and amphetamines, is often seen during a depressive episode. Concomitant alcohol and drug use is associated with a worse course of bipolar disorder. In addition, the use of alcohol and other drugs may mask the symptoms of mania or depression. In other words, in its early stages, bipolar disorder often manifests as alcohol or drug abuse, preventing affected individuals and their families from realizing that a serious mental disorder is the cause of the behavior.
  • bipolar disorder is a lifelong disorder that tends to recur and worsen over time – As many as 90% of people with bipolar disorder experience multiple episodes. These episodes may worsen over time and become more difficult to treat.