Retrospective age at onset of bipolar disorder and outcome during two-year follow-up: Results from the STEP-BD study

Objective: Symptoms of bipolar disorder are increasingly recognized among children and adolescents, but little is known about the course of bipolar disorder among adults who experience childhood onset of symptoms. Methods: We examined prospective outcomes during up to two years of naturalistic treatment among 3,658 adult bipolar I and II outpatients participating in a multicenter clinical effectiveness study, the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD). Age at illness onset was identified retrospectively by clinician assessment at study entry. Results: Compared to patients with onset of mood symptoms after age 18 years (n = 1,187), those with onset before age 13 years (n = 1,068) experienced earlier recurrence of mood episodes after initial remission, fewer days of euthymia, and greater impairment in functioning and quality of life over the two-year follow-up. Outcomes for those with onset between age 13 and 18 years (n = 1,403) were generally intermediate between these two groups. Conclusion: Consistent with previous reports in smaller cohorts, adults with retrospectively obtained early-onset bipolar disorder appear to be at greater risk for recurrence, chronicity of mood symptoms, and functional impairment during prospective observation.