Contrary to forecasts: The rate of dementia patients has actually decreased over the years
A new study challenges countries' forecasts of a "tsunami" of severe dementia patients in the coming decades. Professor Eric Stallard, who led the study, is convinced there is still room for decline. Longevity Science, a new section.
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In 1984, three out of ten Americans aged 85–89 suffered from severe dementia requiring constant help. In 2024, the numbers stood at only one out of ten. This is contrary to the prevailing perception and the basic assumptions of governments. While they anticipate a "tsunami of people with dementia," a global study led by Professor Eric Stallard points, on the contrary, to a decrease in the rates of severe dementia in every age group and argues that this tsunami is not supposed to happen at all.
Not only the rate of those suffering from dementia in every age group, but also their total number, is expected according to Stallard to stabilize and probably even decrease in the coming decades.
Stallard is an actuary and researcher in the Biodemography of Aging unit at Duke University in the USA. "There are not many actuary researchers," he says. "I became an actuary because I wanted to put my research to the test of reality." He presented the data regarding dementia to a group of eight leading actuaries so that they would examine his methodology and ensure it is valid.
He published his article, titled "The Changing Story of the Dementia Epidemic," last year in the leading journal JAMA, after an investment of millions of dollars in data collection and three years of methodological discussions with the group of actuaries.
An $800 billion gap
Stallard showed that the rate of people with severe dementia is gradually decreasing as a percentage in every age group. The rate of decline was 2.5%–3% per year, or about 60% between 1984 and 2024. The data were found first in the USA, and then in several countries in Europe.
"The estimate was always that the rate of dementia would remain constant and therefore when the number of elderly people grows, we will have a tsunami of dealing with dementia," says Stallard. "My data show that the increase in the total number of people with dementia in the USA will be much more moderate, perhaps only 9% by 2050, instead of double, which was the basic assumption until now. And if the population size does not increase at the same rate but the improvements in dementia prevention continue, then eventually the total amount of people with dementia will stabilize and perhaps even decrease. The difference in national health expenditure between the situation being prepared for today and the situation expected according to my calculations is about $800 billion."
The world of actuarial science has not yet fully digested these data, but they are beginning to appear in other studies. Thus, for example, the longitudinal Framingham Heart Study found that the rates of those suffering from dementia from the total sample decreased by 44% between those who reached the age of 65 in 1978 and those who reached this age in 2013.
What leads to this decrease?
Stallard: "The Lancet Commission on dementia prevention defined 14 preventable factors for dementia. They believe that if we attack them all directly, it is possible to reduce dementia rates by up to 45%.
"The paths in which they recommend acting in The Lancet are education at a young age and mental stimulation at an old age for everyone; treatment of vision and hearing problems at a young age, including prevention of noise hazards and making hearing aids accessible; treatment of depression; use of helmets in sports and in any situation where there could be a head injury; encouragement of physical activity; prevention of smoking; prevention of high blood pressure, obesity, and high cholesterol; reduction of alcohol use; encouragement of community and prevention of social isolation; and reduction of air pollution."
A clue to prevention
"I believe it is possible to reduce dementia rates by more than 45%, because we see the beautiful rate of decline, even before the recommendations were implemented, and also because we are constantly discovering more factors that help prevent dementia, such as the vaccine for shingles, which probably has a significant positive effect.
"The commission itself marked another 16 interesting factors but there is less information about them and many other factors that are a clue." And all this, even before we took into account dedicated drugs for specific dementia diseases like Alzheimer's.
Are we just delaying dementia to an older age or increasing the number of people who will not suffer from it at all?
"We saw from the data that someone who reached the age of 65 in 1984 was expected to live another 16 years on average, of which 1.3 years with severe dementia. Someone who reached the age of 65 in 2004 is expected to live another 18 years on average, with severe dementia for 0.9 years on average, and with every additional year we expect a further decrease, although never to zero."
