Editorial: The Early Phenotype of Bipolar Disorder?

In patients with bipolar disorder (BD), there is often a substantial delay before diagnosis and accurate treatment initiation. This delay is associated with a poorer outcome and stresses the importance of early recognition. As BD runs in families, longitudinal studies on children of parents with BD can provide information on the onset and early trajectories of BD. In the past 3 decades, a number of longitudinal studies on offspring of parents with BD have been initiated. With a typical age of onset in late adolescence, most of these studies started in adolescence. Thus far, these studies have shown that 13% to 25% of these children develop BD, they are predominantly at risk for developing mood disorders (>50%), and BD typically starts with a (mild) depressive episode followed by (sub)clinical mania.1 Less is known about the preschool-age period, when preventive interventions hold promise for preserving typical development. In this issue, Birmaher and colleagues2 present findings of their longitudinal study on preschool-aged offspring of parents with BD with a follow-up into early adolescence. Accordingly, this study adds an important piece to the existing literature about the offspring of parents with BD, but also fuels the ongoing debate on pediatric BD.