The estimation of the global prevalence of dementia from 1990‐2019 and forecasted prevalence through 2050: An analysis for the Global Burden of Disease (GBD) study 2019

Background Given projected increases in population growth and population aging, the number of people with dementia is expected to increase in the future. Characterizing the distribution and magnitude of the anticipated growth is critical for public health planning and prioritization of resources. This study aimed to improve on prior forecasts of dementia prevalence by producing country‐level estimates and by incorporating information on trends in dementia risk factors. Method Dementia prevalence from 1990‐2019 was estimated using meta‐analytic techniques. We then forecasted dementia prevalence attributable to the three risk factors included in the Global Burden of Disease (GBD) study (BMI, fasting plasma glucose, and smoking), using relative risks and forecasted risk factor prevalence to predict future risk‐attributable prevalence. Finally, using linear regression models with other dementia risk factors included as predictors, we forecasted dementia prevalence not attributable to GBD risks. To assess the relative contribution of changes in prevalence, population growth and population aging, we conducted decomposition analysis. Result We estimated the number of people with dementia would increase from an estimated 57.4 (50.4 to 65.1) million cases globally in 2019 to an estimated 152.8 (130.8 to 175.6) million cases in 2050. There was geographic heterogeneity in projected increases, with the highest increases observed in eastern sub‐Saharan Africa and North Africa and the Middle East. Despite large increases in the number of projected dementia cases, age‐standardized rates remained largely stable. Decomposition analysis suggested that projected increases in cases could largely be attributed to population growth and aging, although the relative importance of these two factors varied by world region. Conclusion The number of individuals with dementia is expected to grow, due largely to population growth and population aging. However, heterogeneity in expected rates of growth was observed across countries, and the country‐level estimates from this study can be used to inform policy decisions around funding for research and public health planning efforts at the national and international levels. Multifaceted approaches, including scaling up interventions to address modifiable risk factors and investing in research on etiologic disease mechanisms, will be critical in addressing expected increases in the number of individuals affected by dementia.