Bipolar Disorder

S. Nassir Ghaemi, MD

How many people have bipolar disorder?
About ten or fifteen years ago, we thought that 1% of the population had mania or type I bipolar disorder. But, the definitions of bipolar disorder have changed since then, to include hypomania and milder versions. The general prevalence is now thought to be 3% to 5% of the population.

Do more men or women have bipolar disorder?
For type I bipolar disorder, it is equally split among men and women. For hypomania or type II bipolar disorder, and rapid-cycling bipolar disorder, it is more common in women.

Is bipolar disorder hereditary?
Yes, bipolar disorder runs in families; it is the most genetic major psychiatric condition. It is more genetic than schizophrenia and major depression. If you have a parent or sibling with bipolar disorder, then there is a 10-15% likelihood that you will develop it. If you have a second-degree relative like a grandparent or aunt, then the likelihood is half that amount (5-10%).

In twin studies, 60% of the likelihood is due to genes, but 40% is environmental (such as life events, like a divorce or job loss that triggers an episode). In other words, you may have a genetic susceptibility to bipolar episodes, which are only triggered when you experience environmental stressors. So, it is important to have good family support.

What is bipolar disorder and how does it usually present itself?
The official definition of bipolar disorder involves the occurrence of at least one manic or hypomanic episode during one's lifetime. The onset for bipolar disorder is late teens, compared to major depression, in which the onset is usually in the late 20s or early 30s.

Bipolar patients have depression, so they often appear no different than patients with unipolar or major depression. Bipolar patients usually seek treatment when they are depressed. At some point though, they have manic or hypomanic episodes.

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