Bipolar Disorder Risk Factors Identified in Children of Parents With the Disorder

While childhood bipolar disorder is not a common diagnosis, a new study shows that symptoms of the disorder that do not warrant a diagnosis of the illness, such as subthreshold mania and hypomanic episodes, when they appear in children whose parents have bipolar disorder, are risk factors for later development of manic, mixed, or hypomanic episodes. "These results indicate that in the offspring of parents with bipolar disorder, mania and hypomania do not come 'out of the blue' but instead are almost always preceded by identifiable mood episodes and non-mood disorders.... Clinicians should carefully assess for subthreshold manic or hypomanic episodes and differentiate them from symptoms of depression and other disorders in the offspring of parents with bipolar disorder, as they carry prognostic significance for the future development of full-threshold bipolar illness. This may provide an opportunity for early intervention to improve the course of illness," point out the researchers.

The study was led by David Axelson, M.D., of the Department of Psychiatry at Nationwide Children's Hospital in Columbus, Ohio, and colleagues at the University of Toronto Medical Center and the University of Pittsburgh Medical Center. The report, "Diagnostic Precursors to Bipolar Disorder in Offspring of Parents With Bipolar Disorder: A Longitudinal Study," is published in AJP in Advance.

The study compared 391 high-risk children aged 6 to 18 (those with a parent who has bipolar disorder) with 248 matched children from a community sample in which no parent had the illness. The mean follow-up duration was 6.8 years.

Data showed that the high-risk offspring had significantly higher rates of subthreshold mania; hypomania; manic, mixed, or hypomanic episodes; and major depressive episodes than did the children in the community sample. They also had higher rates of attention-deficit/hyperactivity disorder, anxiety disorders, substance use disorders, and disruptive behavior disorders. The analysis of prospective data showed that subthreshold manic or hypomanic episodes were most strongly associated with subsequent manic, mixed, or hypomanic episodes. The researchers suggested, however, that "major depressive episodes and disruptive behavior disorders are also indications for close clinical monitoring of emergent bipolarity in high-risk offspring."

To read more about bipolar disorder research, see the Psychiatric News articles "Link Found Between Glutamate, Adolescent Bipolar Disorder" and "Family-Focused Therapy Reduces Bipolar Symptoms in Youth."

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