Global dementia cases predicted to triple by 2050

02.08.2021 11:02

Positive trends in global education access are expected to reduce dementia prevalence by 6.2 million cases worldwide by 2050. Meanwhile, expected trends in smoking, high body mass index and high blood sugar will increase the prevalence by almost the same number: 6.8 million cases. Both according to new global prevalence data presented at the 2021 Alzheimer's Association International Conference® (AAIC®) in Denver, Colorado.

Taking these projections into account, researchers at the Institute for Health Metrics and Evaluation at the University of Washington School of Medicine reported at AAIC 2021 that they estimate the number of people living with dementia will nearly triple to more than 152 million by 2050. The highest increase in prevalence is predicted for Eastern Sub-Saharan Africa, North Africa and the Middle East.

“Improvements in lifestyle among adults in developed countries and elsewhere – including increased access to education and greater attention to heart health issues – have reduced the incidence in recent years, but the overall number of people with dementia continues to rise due to population aging "," said Maria C. Carrillo, PhD, chief scientist of the Alzheimer's Association. “In addition, obesity, diabetes and sedentary lifestyles are increasing rapidly in younger people, and these are risk factors for dementia.”

The US National Institute on Aging estimates that the proportion of people over 65 in the world population will increase to 16 % by 2050 - up from 8 % in 2010.

Two additional prevalence/incidence studies were also reported at AAIC 2021. Key findings include:

• Each year, an estimated 10 in 100,000 people develop early-onset dementia (before age 65). This corresponds to 350,000 new cases of early-onset dementia worldwide every year.
• From 1999 to 2019, the mortality rate from Alzheimer's disease in the general US population increased significantly from 16 to 30 deaths per 100,000, an increase of 88 %.
• Among all areas of the United States, the mortality rate for Alzheimer's disease was highest in rural areas in the eastern, southern, and central regions of the United States, where the mortality rate for Alzheimer's disease among those age 65 and older is 274 per 100,000.

Global prevalence of dementia is expected to grow rapidly by 2050

To more accurately predict global dementia prevalence and produce country-level estimates, Emma Nichols, MPH, a researcher at the Institute for Health Metrics and Evaluation at the University of Washington School of Medicine, and colleagues used Global Burden of Disease (GBD) data. Study from 1999 to 2019, a comprehensive collection of estimates on health trends worldwide. This study also aimed to improve previous predictions by incorporating information about trends in dementia risk factors.

Nichols and team found that dementia will increase from an estimated 57.4 (50.4 to 65.1) million cases worldwide in 2019 to an estimated 152.8 (130.8 to 175.6) million cases in 2050. The highest increases were observed in eastern sub-Saharan Africa, North Africa and the Middle East. Their analysis found that the projected increase in cases is largely due to population growth and population aging, with the relative importance of these two factors varying by region of the world.

In addition, Nichols and team predicted the prevalence of dementia attributable to smoking, high body mass index (BMI), and high fasting plasma glucose based on the expected relationship between these risk factors and dementia prevalence. They found an increase of 6.8 million dementia cases worldwide between 2019 and 2050, specifically due to expected changes in these risk factors. Separately, the researchers found that expected changes in education levels between 2019 and 2050 will lead to a decline in dementia prevalence by 6.2 million people worldwide. Taken together, these opposing trends almost cancel each other out.

“These estimates will allow policymakers and decision-makers to better understand the expected increase in the number of people with dementia and the drivers of this increase in a given geographic setting,” Nichols said. “The expected sharp increase in the number of people living with dementia highlights the urgent need for research focused on discovering disease-modifying treatments and effective, cost-effective interventions to prevent or delay the onset of dementia.”

Recently published in Alzheimer's & Dementia: In the Journal of the Alzheimer's Association, Nichols and his team estimated, using the same data set, that Alzheimer's disease mortality rates increased by 38.0 % between 1990 and 2019.

“Without effective treatments to stop, slow or prevent Alzheimer’s and all dementias, this number will grow beyond 2050 and continue to impact individuals, caregivers, health systems and governments worldwide,” Carrillo said. “In addition to therapeutics, it is critical to find culturally appropriate interventions that reduce dementia risk through lifestyle factors such as education, diet and exercise.”

The Alzheimer's Association US Study of Protecting Brain Health Through Lifestyle Intervention to Reduce Risk (U.S. POINTER) is a two-year clinical trial examining whether lifestyle interventions that simultaneously target many risk factors protect cognitive function in older adults at increased risk of cognitive decline.

Estimates of the incidence of younger-onset dementia suggest 350,000 new cases per year

The data on dementia of younger ages (Younger-Onset Dementia, YOD), a form of dementia in which symptoms appear before age 65, is extremely limited. To better understand the incidence of YOD, Stevie Hendriks, MSc, a student at Maastricht University in the Netherlands, and colleagues conducted a systematic literature review of all studies published in the last 30 years that provided figures on how many people have it developed dementia after the age of 65.

Hendriks and his team found that the overall global incidence rate is 10 new cases per year per 100,000 people. They also found that the incidence increases with age. This suggests that around 350,000 people worldwide develop dementia at a young age every year. Incidence rates for men and women were similar and were highest for Alzheimer's disease, followed by vascular dementia and frontotemporal dementia.

“Our results should raise awareness among healthcare professionals, researchers and policy makers because they show that a significant number of people are newly affected by young-onset dementia every year,” said Hendriks. “This shows the need for investment in tailored healthcare for this specific patient group and more research into how we can best support, but also prevent and treat, young people with dementia.”

“People living with Alzheimer’s at a younger age face unique challenges when it comes to diagnosis, family, work, finances, future care and, with the recent FDA action, possible treatment options. But support and information is available, says Kristen Clifford, program director for the Alzheimer's Association. “And you have the ability to create a new plan and determine how you want to live your best life with the disease.”

Rural areas of the American South are disproportionately affected by Alzheimer's mortality

Although average life expectancy in the United States has steadily increased over the past few decades, there is an increasing divergence in mortality rates between urban and rural populations. This disparity is likely the result of many health inequalities that rural populations face compared to their urban counterparts, including lower socioeconomic status, higher levels of chronic disease, limited availability of internet services, and poorer access to health services, including the Primary care.

To specifically understand geographic variation in Alzheimer's disease mortality, Ambar Kulshreshtha, MD, PhD, of Emory University and colleagues examined trends in Alzheimer's disease mortality rates between 1999 and 1999 using data from the National Center for Health Statistics 2019 by level of urbanization.

Kulshreshtha and team found that the mortality rate from Alzheimer's disease in the general population increased significantly from 16 to 30 deaths per 100,000 from 1999 to 2019, an increase of 88 %. Rural areas in the United States have been shown to have higher mortality rates from Alzheimer's disease compared to urban areas. These rates were highest in rural areas in the east-southcentral regions, at 274 per 100,000 people age 65 and older, more than three times higher than in urban areas in the Mid-Atlantic region, where mortality rates were lowest.

“Our work shows that there is a growing disparity in Alzheimer's mortality between urban and rural areas. This discrepancy could be related to or result from other urban-rural health inequalities, such as: “Such as access to primary care and other health services, socioeconomic levels, time to diagnosis, and the increasing proportion of older Americans living in these areas,” said Kulshreshtha. “Identifying and understanding the reasons for these health disparities is critical to appropriately allocating important social and public health resources.”