While the overall prevalence of dementia might be rising due to population aging, a study has found that today’s older people seem to be less prone to dementia than in the past [1].
Are we having more dementia or less?
While the robust rise in average life expectancy seen in the previous century has largely stopped, and some scientists claim that we are about to reach the limits of longevity possible with today’s therapies, research continuously show that people do live healthier for longer. It is not black and white, with some worrying signs such as the obesity epidemic and rising cancer prevalence among younger people, but, overall, at least in terms of intrinsic capacity and cognition, 70 might indeed be the new 60.
A new large-scale study from the University of Queensland, Australia has followed several cohorts and compared the prevalence of dementia among people of the same age born in different times. That is, it asks such questions as whether people born in 1900 are more likely to have had dementia in 1980 than people born in 1940 had in 2020.
The researchers analyzed data from 62,437 people, including 21,069 from the U.S., 32,490 from Europe, and 8,878 from England. The study classified participants by both birth year and age at the time of assessment.
Birth year was divided into eight cohorts, each covering approximately five years. These ranged from those born between 1890 and 1913 in the earliest cohort to those born between 1944 and 1948 in the latest. Participants’ ages were also grouped into six categories: 71-75, 76-80, 81-85, 86-90, 91-95, and 96 years and above.
A win for those born later
A population’s prevalence of dementia depends on numerous factors, including major events such as war and famine. While specific results were not always clear-cut and sometimes hard to interpret, the overall trend, according to the authors, was clear: the later cohorts saw less dementia at the same age than the earlier ones.
“We often see statistics that show dementia prevalence rates are increasing; our study doesn’t refute that,” said Dr. Sabrina Lenzen from UQ’s Center for the Business and Economics of Health. “As more people live longer, the total numbers of people diagnosed with dementia will grow. What we found was a statistically significant decline in people from more recent birth cohorts having dementia.”
For instance, among respondents aged 81 to 85, dementia rates differed notably by birth cohort and region. In the United States, 25.1% of those born between 1890 and 1913 were diagnosed with dementia, compared to just 15.5% among those born from 1939 to 1943. A similar trend was observed in Europe: 30.2% of individuals born between 1934 and 1938 developed dementia, while the rate dropped to 15.2% for the 1939-1943 birth cohort. The results for England were murkier, possibly due to a much smaller sample size.
Driven by women
According to Lenzen, this trend can likely be attributed to a wide variety of environmental factors. “There has been a lot of improvement in education, particularly for women, if, for example, we compare to the baby boomer generation,” she said. “We’ve seen improvements in cardiovascular health, better control of blood pressure and cholesterol, all risk factors for dementia.”
The trend was indeed mostly driven by improvements in female populations. “The decreasing trends among women in all 3 regions have been significantly higher than that of men,” the paper says. These results suggest that the decreasing trend in prevalence among women plays an important role in explaining the decrease of age-specific dementia incidence rates.”
This lends some support to the idea that rising education levels for women are responsible. However, since these levels are quickly catching up to those of men, this particular driver of change might soon peter out.
Some other factors that might be in play include steadily decreasing smoking rates, less environmental pollution, and more active lifestyles. Changes in diet are probably a double-edged sword: while many people today eat healthier, many others consume increasingly more ultra-processed foods.
One of this study’s strengths is that, unlike some previous ones, it uses comparable data from three different regions, thus mitigating the impact of region-specific factors such as wars and economic crises. However, more rigorous studies are needed to understand what factors are behind this data.
Dr. Lenzen noted that while the results provided some hope, there was a need for continued investment in public health campaigns. “Some of the risk factors have been improving, but we have been seeing a shift in terms of high obesity rates and things like air pollution,” she said. “We know those are also related to dementia, so it’s not certain these trends will continue.”
Literature
[1] Dou, X., Lenzen, S., Connelly, L. B., & Lin, R. (2025). Generational Differences in Age-Specific Dementia Prevalence Rates. JAMA Network Open, 8(6), e2513384-e2513384.
