Science Update
February 8, 2006
Largest Study to Date on Pediatric Bipolar Disorder Describes Disease Characteristics And Short-Term Outcomes
Recent findings from the multi-site, NIMH-funded Course and Outcome of Bipolar Illness in Youth (COBY) study are helping to shape the understanding of three major subtypes of bipolar disorder that affect children and adolescents and how this diagnosis may affect them as adults. Also known as manic-depressive illness because of its recurring episodes of mania and depression, bipolar disorder is a serious, chronic illness which causes shifts in a person's mood, energy, and ability to function. Before the COBY study, there had been few studies on the symptom patterns and course of the disorder in the pediatric population. Understanding the effects of bipolar disorder early in life may lead to better treatments and improve long-term outcomes as these children and adolescents become adults.Overall, bipolar disorder appears to affect children and adolescents more severely than adults. Study participants had comparatively longer symptomatic stages and more frequent cycling (changing from one mood to another) or mixed episodes. Children and adolescents also converted from a less severe form of bipolar disorder to a more severe form at a much higher rate than seen in adults.
This study comprises the largest pediatric bipolar population to date, following the course and outcome of 263 children and adolescents, ages 7-17 years. These findings were published in the February 2006 issue of the Archives of General Psychiatry. Future reports will cover in more detail the characteristics of bipolar spectrum disorders in children and adolescents, the longer-term disease progression, predictive factors of disease outcome, such as co-occurring disorders or family psychiatric history, and the effects of different types of treatments.
Subtypes of Bipolar Disorder
The three major subtypes of bipolar disorder (BP) included in this study were BP-I, BP-II, and Bipolar Disorder Not Otherwise Specified (BP-NOS), the most commonly seen subtype in pediatric psychiatric clinics. In accordance to guidelines set by the Diagnostic and Statistical Manual-IV (DSM-IV), BP-I was determined by primarily manic (abnormally "high" and/or irritated) episodes and BP-II was determined by an alternating pattern between depressive and hypomanic (a less severe form of mania) episodes. BP-NOS is not clearly defined in the DSM-IV, so the researchers determined this type by "the presence of elated mood, plus two associated DSM-IV symptoms, or irritable mood plus three DSM-IV associated symptoms, along with a change in the level of functioning;" the symptoms had to have lasted at least 4 hours within a 24-hour period for at least 4 "cumulative lifetime days."
Of the total study population who had at least one follow-up assessment over an average time of 1.5 years, 57 percent had BP-I, 8 percent had BP-II, and 35 percent had BP-NOS. Researchers tracked changes in symptoms and instances of recovery or recurrence. Recovery was defined as having 8 consecutive weeks with minimal or no symptoms. Recurrence, or having a new episode, was defined as meeting the full DSM-IV criteria for a particular diagnosis with different degrees of severity or impairment for one week in the case of mania or hypomania (a less severe form of mania), or two weeks in the case of depression.
Symptom Course, Recovery, and Recurrence
Approximately 70 percent of all the study participants recovered from their index episode (the episode that brought them to the study's attention) and 50 percent had at least one recurrence. Those with BP-I recovered and recurred more frequently than those with BP-NOS, who took the longest time to reach recovery or recurrence. On average, during the follow-up period, the participants spent 39.2 percent of the time symptom-free, 22.6 percent meeting the criteria for a DSM-IV episode, and 38.2 percent with some symptoms but not meeting DSM-IV criteria. However, even during the symptom-free periods, many participants had ongoing co-occurring psychiatric disorders (such as attention deficit hyperactivity disorder, or ADHD). In addition, 12 percent experienced at least one week of psychotic symptoms (such as hallucinations or delusions) and 15 percent made at least one suicide attempt or gesture. There were no completed suicides in the COBY study.
Over the follow-up period, 20 percent of those with BP-II converted to BP-I; of those with BP-NOS, 18.5 percent converted to BP-I and 6.5 percent converted to BP-II.
Predictors of Outcome
Younger age of onset, low socio-economic status, and psychotic symptoms were common factors in study participants who had worse outcomes. In comparison with studies of bipolar disorder in adults, the researchers found major differences in the course of illness in children, which may have a serious impact on their emotional, cognitive, and social development.
Compared to adults with BP-I, COBY participants with BP-I spent significantly more time in a symptomatic stage and had more mixed and cycling (changing from one mood to another) episodes, mood symptom changes, and polarity switches. Also, the rate of conversion between BP-II and BP-I found in COBY is higher than the rate of conversion commonly reported in studies on adults. Furthermore, this is the first study to suggest the relative instability of the BP-NOS subtype, due to the number of participants who converted to BP-I or II.
For more information on bipolar disorder in children and adolescents, visit:
Birmaher B, Axelson D, Strober M, Gill MK, Valeri S, Chiappetta L, Ryan N, Leonard H, Hunt J, Iyengar S, Keller M. Clinical course of children and adolescents with bipolar spectrum disorders. Archives of General Psychiatry. 2006 Feb;63(2):175-83.
