Several risk factors including low education and unhealthy lifestyle choices are partially responsible for this projected increase, though investigators believe changes could be made to decrease the number of dementia cases.
The first comprehensive global analysis of dementia forecasted that the number of adults aged 40 years and older living with dementia is expected to nearly triple from an estimated 57 million in 2019 to 153 million in 2050.
Though the increase is multifactorial, investigators believe the increase to be due primarily to population growth and population aging.
The Global Burden of Disease study, which is published in The Lancet Public Health, is the first to provide forecasting estimates for 204 countries worldwide.
Dementia is currently the seventh leading cause of death worldwide and has been cited as one of the major causes of disability and dependency among older people globally. Regarding the financial implications of the disease, the global cost in 2019 was estimated at more than 1 trillion US dollars.
The Global Burden of Disease Study Overview
Investigators led by Emma Nichols, Phd, the Institute for Health Metrics and Evaluation at the University of Washington, evaluated 4 risk factors for dementia: smoking, obesity, high blood sugar, and low education.
These 4 factors, in addition to hearing impairment, depression, physical inactivity, diabetes, social isolation, excessive alcohol consumption, head injury, and air pollution, were previously discussed in a Lancet Commission piece published in 2020.
Investigators from the previous study suggested that up to 40% of dementia cases could be prevented or delayed if exposure to these known risk factors were eliminated.
In the current study, improvements to factors such as global education were projected to reduce dementia prevalence by 6.2 million cases worldwide by 2050.
However, these advancements were anticipated to be countered by trends in obesity, high blood sugar, and smoking. These trends are expected to result in an additional 6.8 million dementia cases.
Study authors predicted that the greatest increase will occur in eastern sub-Saharan Africa, with an expected climb in dementia from nearly 660,000 in 2019 to more than 3 million by 2050 (a 357% increase). This will be mainly driven by population growth.
Similar rates were forecasted in north Africa and the Middle East, with cases predicted to grow by 367%, from nearly 3 million to nearly 14 million.
A smaller increase is projected in Asia Pacific, with the number of dementia cases expected to grow by 53%. A smaller increase in Japan (27%) is expected to fall, which indicated to investigators that preventive measures such as improvements in education and healthy lifestyle are influencing rates in a positive manner.
“These estimates can be used by national governments to make sure resources and support are available for individuals, caregivers, and health systems globally,” said Nichols. ““At the same time, we need to focus more on prevention and control of risk factors before they result in dementia. Even modest advances in preventing dementia or delaying its progression would pay remarkable dividends.”
In a linked comment by 2 doctors from France who were not involved in the study, Dr Michaël Schwarzinger and Dr Carole Dufoui, Bordeaux University Hospital believed that the authors of the Global Burden of Disease study were “still oversimplifying the underlying mechanisms that cause dementia”.
“There is a considerable and urgent need to reinforce a public health approach towards dementia to better inform the people and decision makers about the appropriate means to delay or avoid these dire projections,” the pair said in a shared statement.