Health transitions in late life: Differences by birth cohort and history of depression

Background

Disability in old age is increasingly understood as a dynamic, reversible continuum rather than a static, permanent state, characterized by transitions between independence, compromised health, and functional limitation. Whether these transitions are impacted by the life-course history of depression, a strong contributor to late-life wellbeing, and whether they have varied over time in a high-income setting of Sweden, alongside advances in medical care and old-age survival – remains unclear.

Methods

We used data from 3058 individuals aged 60-107 years from the ongoing population-based Swedish National Study on Aging and Care in Kungsholmen (SNAC-K). The Health Assessment Tool (HAT) incorporating physician-collected measures of gait speed, cognition, multimorbidity, and functional limitation was used to define three states: robust health, compromised function, and functional dependency. Self-reported history of depression over the life-course was collected during nurse interviews. Markov multi-state models were used to model health transitions over 18 years of follow-up and to calculate the amount of time spent in each health state.

Results

Later-born cohorts had longer life expectancy. This manifested both as the expansion of robust health and functional dependency, and as well as the compression of the compromised function. History of depression was associated with higher likelihood of progression towards disability, lower likelihood of recovery from compromised function, and the expansion of time spent in detrimental health states.

Conclusions

These findings indicate both an expansion and a compression of functional dependence among later-born Swedish cohorts, suggesting a complex nature of population aging. Life-course history of depression can further impact these trends. A nuanced understanding of these patterns is important for public health, given the implications for healthcare planning and prevention.

Key messages

• Later-born cohorts have a higher life expectancy, with more time spent in robust health and functional dependency.

• History of depression is associated with a higher likelihood of transitioning to dependency.