Japanese Population Projected to Live Longer Without Dementia

A new microsimulation projects that over the next 20 years, Japanese people will live longer without dementia, but older women with a less than high school education will benefit less than men.
A trio of elderly women in Japan

This press release was originally published by the University of Tokyo. It discusses a new study, published by Lancet Public Health and co-authored by researchers from the University of Tokyo along with FSI Senior Fellow Karen Eggleston, director of the Asia Health Policy Program at APARC, and Jay Bhattacharya, Professor of Health Policy and director of the Center for Demography and Economics of Health and Aging at Stanford.


A new detailed microsimulation, using a database of 40 million people, has examined the future of Japan’s aging population up to 2043. It projects that more people will live longer, and that overall years spent living with dementia will decrease. However, the model highlighted the diversity of impacts on different segments of the population, as Japanese women with a less than high school education aged 75 and over may be disproportionately affected by both dementia and frailty. Better understanding where health gaps like this exist can help inform public health planning, to minimize future economic costs and support those most in need.

Taking care of the older members of society is a common concern around the world. Japan is famous for its long-lived residents, the number of which continues to rise. In 2020, almost 30% of the Japanese population was aged 65 years or older, and this age group is not projected to peak until 2034. Caring for people with age-related ailments, such as dementia and frailty, poses a challenge both to individuals and public health care systems.

Microsimulation models, which are computer models that can provide detailed analysis on an individual basis, are currently used to project future population health in some countries, such as the U.K. and the U.S. Professor Hideki Hashimoto and researchers at the University of Tokyo, along with researchers from Stanford University in the U.S., wanted to create a new microsimulation model for Japan, which would take into account more diverse conditions than had been considered before.

“We developed a new Japanese microsimulation model that accounts for 13 chronic conditions (including heart disease, stroke, diabetes, depression and dependency), as well as frailty and dementia,” explained Hashimoto. “Using an ultralarge data system, we were able to ‘follow’ a virtual cohort of more than 40 million people aged 60 and over from 2016 to 2043.”

According to Hashimoto, projections of aging in Japan usually rely on the “average” status of older people and so don’t consider the diversity of the population. “I believe that problems of aging are a matter of health gaps over the course of people’s lives,” he said. “Our projection brings attention to a widening health gap among older people. It highlighted that women with a less than high school education aged 75 or over are more likely to be affected.”

Identifying where health gaps like this exist could be used to better inform public policy, not only about health care but other influential aspects of life. “Japan’s case may suggest that improvement in educational attainment, as well as population health, could be a key to making a healthier and more manageable aging society,” said Hashimoto.

Positively, this study shows hope for a future where many people live longer and more healthy lives. “People might believe that an increase in cases of dementia is inescapable, given population aging. However, in this study we found that in Japan, despite an aging population, the number of people with dementia is expected to decrease over the next two decades,” said Hashimoto. “Population aging does not necessarily mean an increase of social burden for care, but it does bring a diversity of problems that requires careful study and science-based policy attention, to close the health gap.”

Karen Eggleston 4X4

Karen Eggleston

Senior Fellow at FSI and Director of the Asia Health Policy Program, Shorenstein APARC
Full biography

Read More

Two old men
News

Education Level Will Widen Disparity in Health Outcomes of the Future Elderly Population, New Study Projects

In the first study to compare the progression of educational disparities in disability across two rapidly aging Asian societies, APARC coauthors Cynthia Chen and Karen Eggleston project that from 2015 to 2050, elders with high educational attainment will have a lower prevalence of functional disability and chronic conditions compared to elderly with low educational attainment.
cover link Education Level Will Widen Disparity in Health Outcomes of the Future Elderly Population, New Study Projects
A health worker checks a patient's blood pressure at a clinic in Pokhara, Nepal.
News

New Cross-Country Study Underscores the Importance of Health Workforce Development and Socioeconomic Factors in Affecting Health Outcomes

Analyzing data from 191 World Health Organization member countries, a new study from APARC’s Karen Eggleston indicates that strengthening the health workforce is an urgent task in the post-COVID era critical to achieving health-related Sustainable Development Goals and long-term improvement in health outcomes, especially for low- and lower-middle-income countries.
cover link New Cross-Country Study Underscores the Importance of Health Workforce Development and Socioeconomic Factors in Affecting Health Outcomes
A makeshift barricade is seen in front of a residential area to restrict movement and control COVID-19 spread in Hanoi, Vietnam.
News

COVID-19 Disproportionately Affected Marginalized and Rural Populations in Asia, New Study Shows

In the first report of its kind comparing the impacts of the pandemic on people with chronic conditions in five Asian regions, researchers including APARC’s Karen Eggleston document how the pandemic’s broad social and economic consequences negatively affected population health well beyond those directly suffering from COVID-19.
cover link COVID-19 Disproportionately Affected Marginalized and Rural Populations in Asia, New Study Shows