OBJECTIVES: Older adults living with bipolar disorder (BD) include people with early and late onset of symptoms. This study aimed to clarify the cross-sectional and longitudinal clinical associations of BD with early and late onset.
METHODS: Cohort study of 38 173 men aged 65-85 years followed for up to 17.6 years. We used the Western Australian Data Linkage System to establish the presence of BD, as well as diabetes, cardiovascular and renal diseases, cancer, respiratory and gastrointestinal diseases, alcohol use disorder, dementia, and mortality. The causes of death were recorded according to the International Classification of Diseases. We defined late onset BD using 2 different cut-points: 50 and 60 years.
RESULTS: The prevalence of medical morbidities was greater among participants with than without BD, and cardiovascular diseases were more frequent among those with onset before than after 50 years (odds ratio = 1.72, 95% confidence interval = 1.01, 2.94). Bipolar disorder was associated with increased hazard ratio of dementia and death, but there was no difference between early and late onset participants. Death by suicide or accidents occurred exclusively among BD participants with illness onset <60 years, whereas death associated with strokes and neurodegenerative diseases was more frequent among those with illness onset ≥60 years than in the general population (HR = 2.28, 95% confidence interval = 1.34, 3.88).
CONCLUSIONS: Our results indicate that the clinical associations and outcomes of older adults living with BD are not markedly influenced by age of onset. However, mortality data suggest that differences between older adults with BD onset before and after age 60 years should continue to be explored.