Dementia in Denmark: Uncovering the causes of death and life years lost in a nationwide,register-based cohort study

Abstract

Background

Dementia is associated with increased mortality, yet limited data exist on cause-specific life years lost (LYL) in large national populations.

Objective

To quantify excess all-cause and cause-specific mortality, including life years lost, among older adults with dementia in Denmark using nationwide data.

Methods

We conducted a register-based cohort study of over 2.3 million individuals aged 65+, including 191,038 individuals diagnosed with dementia. Using state-of-the-art LYL methodology, we compared mortality rate ratios (MRRs) and LYL between people with and without dementia, stratified by age and sex, with follow-up covering 22.6 million person-years.

Results

Females and males with dementia had adjusted all-cause MRRs of 2.88 (95% CI: 2.86–2.90) and 3.15 (95% CI: 3.12–3.17), respectively, compared to those without. The average cause-specific LYL among individuals with dementia was 3.73 years (95% CI: 3.71–3.76) for females and 3.96 years (95% CI: 3.93–3.98) for males. Dementia as the underlying cause of death accounted for the majority of life years lost among individuals with dementia, while other major causes of death, such as cancer and heart disease, were associated with fewer lost years compared to the general population.

Conclusions

The findings underscore the substantial mortality burden associated with dementia among older adults in Denmark. Recognizing dementia as a life-threatening condition highlights the urgent need for targeted public health and policy responses. Including LYL in prognostic considerations may also improve clinical care planning and support services following diagnosis.