Dementia remains the major predictor of death among octogenarians. A study of two population cohorts of 85-year-olds examined 22 years apart.

Dementia is the major predictor of death in old age. The aim of this paper was to determine whether 8-year mortality among 85-year olds with and without dementia, and if the contribution of dementia to mortality relative to other common diseases has changed. We used two population-based cohorts of 85-year-olds (N = 1065), born in 1901-02 and 1923-24, which were examined with identical methods in 1986-87 and 2008-2010 and followed for 8-year mortality according to data from the Swedish Tax Agency. Dementia was diagnosed according to DSM-III-R. Other diseases were diagnosed based on self-reports, close informant interviews, somatic examinations, and the Swedish National In-patient Register. Compared to cohort 1901-02, cohort 1923-24 had a lower 8-year mortality both among those with (HR 0.7; 95% CI 0.5-0.99) and without dementia (HR 0.7; 95% CI 0.5-0.9). Dementia was associated with increased mortality in both cohorts (cohort 1901-02, HR 2.6; 95% CI 2.0-3.2, cohort 1923-24, HR 2.8; 95% CI 2.3-3.5), and remained the major predictor of death, with a population attributable risk of 31.7% in 1986-87 and 27.7% in 2008-10. Dementia remained the most important predictor of death in both cohorts. The relative risk for mortality with dementia did not change between cohorts, despite a decreased mortality rate in the population.