The number of American children with bipolar disorder significantly increased between 1994 and 2003, and the number of adults diagnosed with the disorder almost doubled over the same period, according to an article in the September issue of Archives of General Psychiatry.

“Although bipolar disorder may have its onset during childhood, little is known about national trends in the diagnosis and management of bipolar disorder in young people,” the authors wrote as background information in the article.

Carmen Moreno, MD, of the Hospital General Universitario Gregorio Maranon, Servicio de Psiquiatria, Madrid, Spain, and colleagues analyzed data from a national survey of office-based physicians designed to represent all such clinicians in the United States. The physicians provided information about demographic, clinical and treatment aspects of each patient visit for a one-week time period.

The researchers compared the rate of growth in bipolar disorder diagnoses among individuals age 19 years and under to that of individuals age 20 years and older from 1994 to 1995 through 2002 to 2003. They also compared demographic information and prescribed treatments between the two groups during the years 1999 to 2003.

The annual number of office-based visits with a diagnosis of bipolar disorder in youth was estimated to increase from 25 per 100,000 youth in 1994 to 1995 to 1,003 per 100,000 youth in 2002 to 2003. In the same time, outpatient visits with a diagnosis of bipolar disorder in adults increased from 905 to 1,679 per 100,000 population.

As a percentage of total office-based visits, visits with a diagnosis of bipolar disorder increased among youth from 0.01 percent (1994 to 1995) to 0.44 percent (2002 to 2003), and among adults, from 0.31 percent to 0.5 percent in the same time periods.

Between 1999 and 2003, most young people diagnosed with bipolar disorder were male (66.5 percent), while 67.6 percent of diagnosed adults were females. Young people were more likely than adults to receive diagnoses of both bipolar disorder and attention-deficit/hyperactivity disorder (32.2 percent versus 3 percent).

“The impressive increase in the diagnosis of childhood and adolescent bipolar disorder in U.S. office-based practice indicates a shift in clinical diagnostic practices,” the authors wrote. “In broad terms, either bipolar disorder was historically underdiagnosed in children and adolescents and that problem has now been rectified, or bipolar disorder is currently being overdiagnosed in this age group. Without independent systematic diagnostic assessments, we cannot confidently select between these two competing hypotheses.”

Most youth (90.6 percent) and adults (86.4 percent) were prescribed medications to treat bipolar disorder, including mood stabilizers, antipsychotics and antidepressants. These similarities occurred despite the fact that the condition and treatments may affect adults and children differently, the authors noted.

“There is an urgent need to study the reliability and validity using multiple informant strategies of the diagnosis of child and adolescent bipolar disorder in community practice and to evaluate the effectiveness and safety of pharmacological treatment regimens commonly used to treat youth diagnosed with bipolar disorder,” they concluded.