Introduction to Bipolar Disorder

Incidence of Bipolar Disorder

It is estimated that between 2 million to 2.5 million Americans suffer from bipolar disorder in any given year. This constitutes approximately 1% of the population 18 years and older. Bipolar disorder occurs equally among men and women. On the average, adults in the United States with bipolar disorder report that their initial episode was often depression, and 20-40% of these adults had onset of symptoms prior to age 18.

According to the American Psychiatric Association, 0.8% of the adult population is affected by bipolar I and 0.5% of the population by bipolar II. Bipolar I affects men and women equally but Bipolar II tends to be more predominant in women.

Onset of initial episodes is usually in late adolescence (between the ages of 15-19) or slightly later (between the ages of 20-24). It has been known to occur in children as young as five years old (very rare) and in older adults between the ages of 40-60. When bipolar develops after the age of 60, it is usually secondary to identifiable medical conditions (e.g., stroke).