Bipolar disorder more common.

A new survey indicates that as many as 4% of American adults might have bipolar disorder at some point in their lifetime, higher than the 1% prevalence found in previous surveys. Researchers from the National Institute of Mental Health queried about 9,282 people from 2001 to 2003 as part of the National Comorbidity Survey-Replication. Based on the survey, the authors reached lifetime estimates of 1% for bipolar I disorder; 1.1% for bipolar II disorder; and 2.4% for subthreshold bipolar disorder. Most patients with a lifetime history of bipolar disorder and lifetime treatment were under the care of psychiatrists; patients with subthreshold bipolar disorder were more likely to receive care from a general medical professional. The study appeared in the May issue of the Archives of General Psychiatry.