Subthreshold Episodes of Mania Best Predictor of Bipolar Disorder in Children
Relatively little attention has been paid to the children of a parent with bipolar disorder, who are at risk not only for the onset of bipolar disorder, but also anxiety, depression, and multiple other disorders. These children deserve a special focus, as on average 74.2% will receive a major (Axis 1) psychiatric diagnosis within seven years.
New research published by David Axelson and colleagues in the American Journal of Psychiatry describes a longitudinal study comparing children who have a parent with bipolar disorder to demographically matched children in the general public. Offspring at high risk for bipolar disorder because they have a parent with the disorder had significantly higher rates of subthreshold mania or hypomania (13.3% versus 1.2%) or what is known as bipolar disorder not otherwise specified (BP-NOS); manic, mixed, or hypomanic episodes (9.2% versus 0.8%); major depressive episodes (32.0% versus 14.9%); and anxiety disorders (39.9% versus 21.8%) than offspring of parents without bipolar disorder. Subthreshold episodes of mania or hypomania (those that resemble but do not meet the full requirements for bipolar disorder in terms of duration) were the best predictor of later manic episodes. This finding was observed prospectively, meaning that patients who were diagnosed with manic episodes during a follow-up assessment were likely to have been diagnosed with a subthreshold manic or hypomanic episode during a previous assessment.
The study included 391 children (aged 6–18) of at least one bipolar parent, and compared these to 248 children of parents without bipolar disorder in the community. The participants took part in follow-up assessments every 2.5 years on average, for a total of about 6.8 years. Each follow-up assessment included retrospective analysis of symptoms that had occurred since the previous assessment.
In addition to having more subthreshold manic or hypomanic episodes; manic, mixed, or hypomanic episodes; and major depressive episodes, the high-risk children also showed more non-mood-related axis 1 disorders, including attention deficit hyperactivity disorder (ADHD), disruptive behavior disorders, and anxiety disorders than the children of parents without bipolar disorder. Axelson suggested that monitoring for these symptoms may help with early identification and treatment.
Children with a bipolar parent were diagnosed with bipolar spectrum disorders at rates of 23% compared to 3.2% in the comparison offspring. Mean age of onset of mania or hypomania in the high-risk offspring was 13.4 years. Of those offspring who had a manic episode, more than half had the episode before age 12, with the earliest occurring at age 8.1.
Compared to previous studies of children of parents with bipolar disorder, this study found that the mean age of onset of manic or hypomanic episodes was younger, possibly because other studies did not include young children. Another new finding was that major depressive episodes were risk factors for mania and hypomania but did not always precede the onset of mania or hypomania in the high-risk offspring.
Parents of children who are at high risk for developing bipolar spectrum disorders should be aware of the common precursors to mania—subthreshold manic or hypomanic symptoms and non-mood disorders—and make sure that clinicians assess for these symptoms and differentiate them from the symptoms of depression or other disorders.
Editor’s Note: In Axelson’s study, 74.2% of the offspring of a bipolar parent suffered a major (Axis I) psychiatric disorder. However, 48.4% of the offspring from the comparison group of community controls also had an Axis 1 psychiatric disorder. These high rates of illness and dysfunction indicate the importance of monitoring a variety of symptom areas and getting appropriate evaluation and treatment in the face of symptoms that are associated with impairment in both high risk children and in the general population.
One way of doing this is for parents to join our new Child Network, a study collecting information about how children at risk for bipolar disorder or with symptoms of bipolar disorder are being treated in the community and how well they are doing. Parents rate their children on a weekly basis for depression, anxiety, ADHD, oppositionality, and mania-like symptoms. Parents will be able to produce a longitudinal chart of their children’s symptoms and response to treatment, which may assist their child’s physician with early detection of illness and with treatment. See here for more information and to access informed consent documents.
