Published in the Lancet Public Health, results from a forecasting analysis estimate that the number of individuals living with dementia will triple between 2019 and 2050. This growth is largely attributable to population growth and aging, with countries experiencing the most population growth expected to bear the greatest increases in dementia prevalence.
This study used country-specific estimates of dementia prevalence calculated as part of the 2019 Global Burden of Diseases, Injuries, and Risk Factors Study (GBD). Country-specific numbers were leveraged to compute global and region-specific prevalence. Prevalence was first forecasted for dementia attributable to 3 primary risk factors: high body mass index (BMI), high fasting plasma glucose, and smoking. Projected changes in exposure to these risk factors were factored into forecast estimates.
Linear regression was used to forecast the prevalence of dementia not attributable to these risk factors. A decomposition analysis was performed to assess the relative contributions of the following factors to future dementia prevalence: risk factors, education, population aging, and population growth.
Between 2019 and 2050, the estimated number of individuals living with dementia is forecasted to increase from 57.4 (95% uncertainty interval [UI], 50.4-65.1) million to 152.8 (130.8-175.9) million. However, the percentage change in prevalence is estimated at 0.1% (95% UI, -7.5 to 10.8%), suggesting that the proportion of affected individuals will remain stable compared to the overall population.
In forecasting analyses, dementia prevalence was higher in women compared with men and increased with age. For men, the estimated age-specific dementia prevalence rates in 2050 were 0.5% (95% UI, 0.4 to 0.7%) among those aged 40-69 years; 6.5% (5.3-8.0%) among those aged 70-84 years; and 23.5% (19.1-29.2%) among those aged 85 years and older. Among women, the corresponding age strata estimates were 0.6% (0.5-0.8%), 8.5% (7.0-10.4%), and 30.5% (25.0-36.8%), respectively.
Estimated changes in dementia prevalence were largely attributable to population growth and population aging. The percentage change in total number of dementia cases was greatest in countries within the lowest sociodemographic index (SDI) quintile (+330% [95% UI, 295-362]). By region, the greatest projected increases in dementia cases were in North Africa and the Middle East (+367% [95% UI, 329-403]) and Eastern sub-Saharan Africa (+357% [323-395]). The smallest estimated increases were in high-income Asia Pacific (+53% [95% UI, 41-67]) and Western Europe (+74% [58-90]). Increases in the prevalence of high BMI and high fasting plasma glucose levels were also found to affect forecasted dementia risk, though population aging and growth were the most prominent factors.
Results from this study emphasize the importance of dementia-focused research and care. Driven largely by population growth and aging trends, the number of dementia cases is expected to triple by 2050. Additional high-quality epidemiological data are necessary to confirm these findings, particularly for countries with a low baseline level of data on dementia prevalence.
“The country-level specificity of our estimates will allow policymakers and decision-makers to understand the expected increases in the number of individuals with dementia and the drivers of these increases in a given geographical setting,” investigators wrote.
“This information might be helpful for public health planning efforts, particularly as they relate to scaling up the availability of resources required to meet the needs of individuals with dementia and their caregivers.”
Disclosure: Several study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
GBD 2019 Dementia Forecasting Collaborators. Estimation of the global prevalence of dementia in 2019 and forecasted prevalence in 2050: an analysis for the Global Burden of Disease Study 2019. Lancet Public Health. Published online January 6, 2022. doi:10.1016/S2468-2667(21)00249-8