Children with bipolar disorder experience more enduring and rapidly changing symptoms of the disease than adults, according to a study that, for the first time, maps the clinical progression of each of the three sub-types of bipolar disorder in children and adolescents.
The findings were published by researchers from the University of Pittsburgh School of Medicine in the February issue of Archives of General Psychiatry. An estimated one out of 100 children and teenagers worldwide has bipolar disorder.
"Bipolar disorder is a serious illness that often emerges in adolescence, yet the majority of research into the disease has been done in adults. It became clear that we needed to define how bipolar disorder presents itself in this young, vulnerable population so we could take the next step of developing more age-specific treatments and therapies," said Boris Birmaher, M.D., professor of psychiatry at the University of Pittsburgh School of Medicine, and principal investigator and lead author of the study. "We found that the symptoms of bipolar disorder were longer lasting and more variable in youths than in adults. To have such symptoms at a young age deprives these children of the opportunity to experience normal emotional, cognitive and social development, establishing the urgent need to diagnose and treat these patients early on."
The study assessed the symptoms of 263 children and adolescents between the ages of 7 and 17 years who were diagnosed with bipolar spectrum disorders. Bipolar disorder, commonly called manic-depressive illness, is characterized by swings between depression, mania and periods with mixed symptoms. Bipolar spectrum disorders consist of three sub-types. Bipolar I (BP-I) is characterized by episodes of full-blown mania and major depression; bipolar II (BP-II) involves episodes of less severe mania, called hypomania, and major depression. The third sub-type, called bipolar not otherwise specified (BP-NOS), was defined in this study as having symptoms consistent with elated or irritable moods that are disruptive to daily living, plus two to three other symptoms of bipolar disorder, such as changes in sleep and appetite, difficulty with concentration or inappropriate social behavior.
Participants were interviewed on average every 35 weeks over a time period of approximately two years. Their symptoms, family history and socio-economic status were evaluated using a host of well-accepted clinical evaluation tools.
Researchers found that participants were symptomatic with either manic or depressive moods 60 percent of the time. While two-thirds of the participants recovered from their initial episode, half had at least one full recurrence of a manic or depressive episode. Participants with BP-I and BP-II experienced faster recovery, but also experienced a shorter time to recurrence, while the BP-NOS group had more protracted illness. Those with BP-I had more manic and mixed episodes, consisting of both mania and depression, than those with BP-NOS, and those with BP-II had more depression than those with BP-I and BP-NOS. Those with BP-NOS were more likely to display symptoms of bipolar disorder that were not severe enough to warrant a diagnosis of a manic or depressive episode.
In comparison to adults with bipolar disorder, researchers found that children and adolescents experienced faster cycling between symptomatic periods. Adults may go months to years between cycles, where as in children, the researchers found the lapse of time to be a matter of weeks.
Interestingly, over the course of the study participants showed numerous and significant changes in their symptoms, often leading to changes in diagnoses. Twenty percent of the participants with BP-II converted to BP-I and 25 percent of the BP-NOS group transitioned to a diagnosis of BP-I or BP-II.
The Course and Outcome of Bipolar Illness in Youths (COBY) study is a collaborative National Institute of Mental Health-funded study being conducted by the University of Pittsburgh, Brown University and the University of California at Los Angeles. It is the largest study of pediatric patients with bipolar disorder to date, and the first prospective naturalistic study of children and adolescents with bipolar spectrum disorders.