Clinical correlates of late-onset versus early-onset bipolar disorder in a global sample of older adults

Objectives: Late-onset bipolar disorder (LOBD) represents a significant subgroup of bipolar disorder (BD). However, knowledge for this group is mostly extrapolated from small studies in subjects with early/mixed age of illness onset. In this global sample of older adults with BD (OABD: ≥50 years old) we aim to characterize the sociodemographic and clinical presentation of LOBD (≥40 years at BD onset) compared to early-onset BD (EOBD: 0.05). Late-onset bipolar disorder was associated with higher endocrine comorbidities (odds ratio = 1.48, [95%CI = 1.0,12.1], p = 0.03). This difference did not remain significant when subjects with BD onset ≥50 years old were analyzed. Limitations: This study is limited by the retrospective nature of the variable age of onset and the differences in evaluation methods across studies (partially overcame by harmonization processes). Conclusion: The present analysis is in favor of the hypothesis that LOBD might represent a similar clinical phenotype as classic EOBD with respect to core BD symptomatology, functionality, and comorbid physical conditions. Large-scale global collaboration to improve our understanding of BD across the lifespan is needed.