Bipolar disorder (BD) typically starts in adolescence or young adulthood (early-onset; EO-BD), which may have different backgrounds and consequences than late-onset (LO) BD. There are controversies over pre-pubertal age of onset (AoO).

To give an overview of the various concepts of AoO in BD, the impact of AoO on subsequent illness course, and findings of the Stanley Foundation Bipolar Network (SFBN) with relationship to AoO.

literature review and additional analyses of SFBN database.

BD usually begins with a depressive episode. SFBN-data reveal that an earlier AoO is associated with a less favourable prospective illness course (more depression, mood instability and rapid cycling), longer delay to first treatment, past history of suicide attempts, being abused in childhood abuse, more psychiatric and medical comorbidities. Comparison of the US sample with the European sample of SFBN showed an earlier onset in US patients.

and early AoF of BD is associated with a poorer long-term outcome, despite adequate current treatment.

The author has not supplied his declaration of competing interest.