Projection for dementia burden in China to 2050: a macro-simulation study by scenarios of dementia incidence trends

Abstract

Background: It is unclear how temporal trends in dementia incidence, alongside fast-changing demography, will influence China's future dementia burden. We developed a Markov model that combines population trends in dementia, mortality, and dementia-related comorbidities, to forecast and decompose the burden of dementia in China to 2050.

Methods: Population-based Chinese ageing cohorts provided input data for a 10-health-state Markov macrosimulation model, IMPACT-China Ageing Model (CAM), to predict sex- and age-specific dementia prevalence among people aged 50+ by year to 2050. We assumed three potential future scenarios representing the range of likely dementia incidence trends: upward (+2.9%), flat (0%) or downward (-1.0%). Sensitivity analyses were conducted to examine uncertainty associated with trends in mortality rates and CVD incidence. The projected dementia burden was decomposed into population growth, population ageing, and changing dementia prevalence corresponding to the three incidence trend scenarios.

Findings: Under the upward trend scenario, the estimated number of people living with dementia is projected to rise to 66.3 million (95% uncertainty interval (UI) 64.7-68.0 million), accounting for 10.4% of the Chinese population aged 50+ by 2050. This large burden will be lower, 43.9 (95% UI 42.9-45.0) million and 37.5 (95% UI 36.5-38.4) million, if dementia incidence remains constant or decreases. Robustness of the projection is confirmed by sensitivity analyses. Decomposition of the change in projected dementia cases indicates dominate effects of increasing dementia prevalence and population ageing, and a relatively minor contribution from negative population growth.

Interpretation: Our findings highlight an impending surge in dementia cases in China in the forthcoming decades if the upward trend in dementia incidence continues. Public health interventions geared towards dementia prevention could play a pivotal role in alleviating this burgeoning disease issue.

Funding: National Science Foundation of China/UK Economic and Social Research Council.

Keywords: China; Decompose analysis; Dementia incidence trend; Dementia prevalence projection; Modelling study.

Fig. 1

Projected number (A) and prevalence of dementia cases (unstandardized and age- & sex-standardized) (B) for the Chinese population aged 50+ years, 2020–2050, forecast under three scenarios of temporal trend in dementia incidence: 2.9% relative annual increase (red line), no calendar effect (green line) and 1.0% relative annual reduction (blue line). Shade indicates 95% uncertainty intervals.

Fig. 2

Sensitivity analysis with alternative assumption on constant mortality rate since 2022 (A) or constant CVD incidence since 2015 (B). The table below indicates the number of dementia cases changed (%) between sensitivity and main analyses for three dementia incidence trend scenarios.

Fig. 3

Composition of annual changes in dementia cases of the Chinese population aged 50 + years between 2020 (ref) and 2050 by dementia prevalence of three incidence scenarios, population ageing and population growth.