Subthreshold mania signals impending bipolarity in children of bipolar patients

By Eleanor McDermid, Senior medwireNews Reporter

Subthreshold manic or hypomanic symptoms frequently precede clinical mood episodes in the children of patients with the condition, a study shows.

“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”, advise David Axelson (Nationwide Children’s Hospital and Ohio State University College of Medicine, Columbus, USA) and co-researchers.

The team studied 391 children, aged 6–18 years, who had a parent with bipolar disorder. These children had significantly higher rates of subthreshold mania or hypomania than 248 children matched for age, gender and locality, at 13.3% versus 1.2%.

They were also more likely to have manic, hypomanic or mixed episodes, major depressive episodes, and non-mood axis I disorders, including anxiety disorders and substance use disorders.

Among 344 children with no baseline history of mania or hypomania who were prospectively followed up for an average of 6.8 years, having subthreshold manic or hypomanic episodes increase the risk of developing manic, hypomanic or mixed episodes a significant 7.57-fold.

Detection of subthreshold mania or hypomania may therefore “provide an opportunity for early intervention to improve the course of illness”, write the researchers in The American Journal of Psychiatry.

Among all the children, disruptive behaviour disorders or major depressive episodes, as well as subthreshold manic or hypomanic episodes, significantly increased the risk of developing manic, hypomanic or mixed episodes.

This suggests that these conditions are also “indications for close clinical monitoring in high-risk offspring”, says the team.

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