The impact of age at onset of bipolar I disorder on functioning and clinical presentation

Objectives: Recent studies have proposed the existence of three distinct subgroups of bipolar 1 disorder based on age at onset (AAO). The present study aims to investigate potential clinical and functional differences between these subgroups in an Australian sample. Methods: Participants (n = 239) were enrolled in the Bipolar Comprehensive Outcomes Study (BCOS), a 2-year longitudinal, observational, cross-sectional study. Assessment measures included the Young Mania Rating Scale (YMRS), Hamilton Depression Rating Scale (HAMD21), Clinical Global Impressions Scale (CGI-BP), SF-36, SLICE/Life Scale, and the EuroQol (EQ-5D). Participants were also asked about their age at the first major affective episode. Results: Three AAO groups were compared: early (AAO < 20, mean = 15.5 ± 2.72; 44.4% of the participants); intermediate (AAO 20–39, mean = 26.1 ± 4.8; 48.14% of the participants) and late (AAO > 40, mean = 50.6 ± 9.04; 7.4% of the participants). Higher rates of depression, suicidal ideation and binge drinking were reported by the early AAO group. This group also reported poorer quality of life in a number of areas. The early AAO group had a predominant depressive initial polarity and the intermediate group had a manic predominance. Conclusion: Early AAO is associated with an adverse outcome.