Prevalence of Bipolar Disorder
The term lifetime prevalence (LTP) describes the number of people within a population who are expected to develop a particular disorder at some time in their lives. The number is generally expressed as a percentage of "at risk" people within the context of a larger population. If there are 1000 people in the total population, and 100 of them get a particular illness at some point during their lifetimes, then the LTP for that illness is 10%, as 10% of the people within the population came down with that illness at some point in their lives.
For bipolar disorder, the LTP varies between 0.4% and 1.6% in diverse community studies [DSM-IV]. This means that in the United States, about 2 million adults (roughly 1% of the adult population) suffer from some form of bipolar disorder. According to several studies, a significant proportion of the approximately 3.4 million children and adolescents with depression in the United States may actually be experiencing the early onset of adolescent bipolar disorder, but have not yet experienced the manic phase of the illness. It is suspected that a significant number of children diagnosed in the United States with attention-deficit disorder with hyperactivity (ADHD) actually have early-onset bipolar disorder instead of or along side of ADHD. For example, an elementary school age child who seems difficult to settle in a classroom and cannot concentrate or refuses to do so might actually be showing the first adolsecent bipolar disorder signs.
Course of Bipolar Disorder
Bipolar disorder typically develops in late adolescence or early adulthood. The average age of onset is 20 for both men and women. However there is some variability in the age of onset that needs to be recognized. Some people have their first bipolar disorder symptoms during childhood, and some develop them later in life. The symptoms are often not recognized as a bipolar mood disorder right away. People may suffer for years before the condition is properly diagnosed and treated.
Bipolar disorder is a recurrent condition. More than 90% of individuals who have a single manic episode go on to have future episodes. About 60-70% of manic or hypomanic episodes occur before or after a major depressive episode. The frequency of swings during a lifetime is typically increased in those suffering from Bipolar II Disorder compared to other bipolar conditions. Approximately, 5-15% of these patients become rapid-cyclers with a poorer prognosis.
Once bipolar disorder signs have established themselves, episodes of mania and depression characteristically recur across the life span. Bipolar disorders have no cure and are chronic conditions. The risk of suicide is high among those with manic-depressive illness; approximately 10-15% of people with a bipolar diagnosis complete suicide while many more attempt suicide unsuccessfully. Bipolar patients are also at heightened risk for engaging in impulsive and risky acts other than suicide such as violent outbursts, domestic abuse, substance abuse, etc.
Fortunately, the worst (e.g., most dangerous) symptoms can be controlled and stabilized in most cases provided that proper bipolar disorder medications are prescribed and complied with. Approximately 20-30% of individuals with Bipolar I Disorder and 15% of individuals with Bipolar II Disorder will continue to display mood lability, interpersonal and occupational challenges despite bipolar disorder treatment compliance. Ongoing prophylactic (protective) treatment is generally recommended for patients even when they have not shown evidence of mood swings for extended periods of time so as to prevent the possible recurrence of suicide and other risky impulsive self-destructive behaviors.