new research suggests.
Results from a study of 195 countries and territories estimates that by 2050, 153 million people are expected to have dementia worldwide – up from 57 million in 2019. In the United States, the number is expected to increase 100%, from an estimated 5.3 million in 2019 to 10.5 million in 2050.
The increase is largely driven by population growth and population aging, but researchers noted that expanding access to education and addressing risk factors such as obesity, high blood sugar, and smoking could blunt the rise in cases.
The study predicts increases in dementia in every country included in the analysis. The sharpest rise is expected in north Africa and the Middle East (367%) and sub-Saharan Africa (357%). The smallest increases will be in high-income countries in Asia Pacific (53%) and western Europe (74%).
Although the United States had the 37th lowest percentage increase across all countries considered, “this expected increase is still large and requires attention from policy and decision-makers,” said coinvestigator Emma Nichols, MPH, a researcher with the Institute for Health Metrics and Evaluation at the University of Washington, Seattle.
The findings were published online Jan. 6, 2022, in The Lancet Public Health (doi: 10.1016/S2468-2667[21]00249-8).
Dementia prevalence
For the study, researchers used country-specific estimates of dementia prevalence from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 study to project dementia prevalence globally, by world region, and at the country level.
They also used information on projected trends in four important dementia risk factors (high body mass index, high fasting plasma glucose, smoking, and education) to estimate how changes in these risk factors might impact dementia prevalence between 2019 and 2050.
Despite large increases in the projected number of people living with dementia, age-standardized both-sex prevalence remained stable between 2019 and 2050, with a global percentage change of 0.1% (95% uncertainty interval, –7.5 to 10.8).
Dementia prevalence was higher in women than in men and increased with age, doubling about every 5 years until 85 years of age in both 2019 and 2050 (female-to-male ratio, 1.67; 95% UI, 1.52-1.85).
Projected increases in cases could largely be attributed to population growth and population aging, although their relative importance varied by world region. Population growth contributed most to the increases in sub-Saharan Africa and population aging contributed most to the increases in east Asia.
The countries with the highest expected percentage change in total number of dementia cases between 2019 and 2050 were: Qatar (1,926%), United Arab Emirates (1,795%), Bahrain (1,084%), Oman (943%), Saudi Arabia (898%), Kuwait (850%), Iraq (559%), Maldives (554%), Jordan (522%), and Equatorial Guinea (498%).
The countries with the lowest expected percentage change in total number of dementia cases between 2019 and 2050 were Japan (27%), Bulgaria (37%), Serbia (38%), Lithuania (44%), Greece (45%), Latvia (47%), Croatia (55%), Ukraine (55%), Italy (56%), and Finland (58%).