The number of new dementia cases each year is projected to more than double by 2050.
This is according to a study published in October in JAMA Neurology. In addition to a 116% increase in the number of new cases, previous research suggests that the total number of dementia cases is projected to reach 150 million globally, as noted by the study authors.
The research also found that dementia incidence was higher among women and individuals in low- and middle-income countries (LMICs).
“For the first time, we can compare dementia incidence across a geographically diverse group of populations using the same statistical approach, giving us a clearer picture of where and among whom new cases are occurring,” Ashleigh Vella, PhD, lead study author, and postdoctoral research fellow at the Centre for Healthy Brain Aging (CHeBA), UNSW Sydney, said in a press release.
“Understanding these differences is critical if we are to develop dementia prevention, diagnosis, and care strategies that respond to the populations facing the greatest future risk.”
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In 2023, there were an estimated 11.4 million new dementia cases worldwide. The researchers projected that this figure will rise to 24.7 million new dementia cases annually by 2050, a 116% increase over 27 years.
To estimate this increase, they analyzed data from 22 studies involving 38,418 participants across 18 countries or territories.
A total of 3,001 people developed dementia after a follow up of 287,632 person-years. The researchers calculated an incidence of 9.7 new cases per 1,000 person-years after accounting for differences in the age and sex of participants.
These figures assume the same rate of occurrence each year, with an aging population accounting for the rise in new cases annually.
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Emer MacSweeney, MBBS, MRCP, FRCR, consultant neuroradiologist and CEO at Re:Cognition Health, spoke with Medical News Todayabout these findings.
“We need to put this figure into context. People are living longer, and age remains the biggest risk factor for dementia, so an increase in cases is expected. But I wouldn’t dismiss it as an inevitable consequence of aging. It is a wake-up call to accelerate prevention, diagnosis, and treatment,” said MacSweeney, who was not involved in the study.
She added, “The encouraging news is how far dementia research has changed our understanding of and treatment for Alzheimer’s. We know so much more about the biological processes driving Alzheimer’s and can identify certain disease-related change earlier. […] Continued research, alongside better management of modifiable risk factors, could improve, significantly, the trajectory of Alzheimer’s we are projecting today.”
The study found an age-standardized incidence rate of 10.6 per 1,000 person-years among women, compared with a lower 8.6 per 1,000 person-years among men.
The researchers did not establish why the incidence was higher among women. They did suggest that reasons other than an average longer life span among women, such as sex-specific factors like menopause and estrogen exposure, could play a role, but this has not yet been determined.
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MNT asked MacSweeney whether it was surprising that women had a higher age-standardized incidence of dementia than men.
“The difference is not entirely surprising, as women have a higher lifetime burden of dementia, but longer life expectancy does not necessarily explain everything,” responded MacSweeney.
“The study reported 10.6 new cases per 1,000 person-years in women, compared with 8.6 in men. That is a notable difference, although we should avoid calling it statistically significant without confirmation from the relevant statistical tests.”
There were 13.6 cases per 1,000 person-years in LMICs, according to the study. This compares with 8.3 cases per 1,000 person-years in high-income countries.
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However, the study authors also note that LMICs are underrepresented. The study included data from 12 high-income countries but only 6 LMICs.
While the exact reason for the difference in incidence has not been determined, the researchers suggest that various factors could play a role, including:
“Cardiovascular health likely plays a role,” explained MacSweeney. “High blood pressure, diabetes, obesity, and smoking all affect the brain, while access to prevention and healthcare varies considerably around the world. However, these findings do not prove that these factors alone explain the difference.”
The higher incidence of dementia among women highlights the importance of investigating risk factors that may affect women differently from men.
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The researchers highlight the importance of sex-specific prevention needs and the necessity to prioritize sex-specific risk factors.
The study suggests that cardiometabolic factors and hormonal changes could play a role, though more research is necessary.
MacSweeney said, “Women may have additional considerations, including the potential influence of menopause and reproductive factors, but we are not yet at the point of recommending an entirely separate prevention strategy.”
She added, “For everyone, the fundamentals remain important: control blood pressure and cholesterol, exercise regularly, don’t smoke, eat well, manage diabetes, protect hearing and vision, and maintain social connections. These are practical steps that can support brain health, although they cannot eliminate risk entirely.”
