Leader:
Erika Kobayashi
Members (Tokyo Metropolitan Institute for Geriatrics and Gerontology):
Hiroshi Murayama, Masumi Takeuchi, Yoh Murayama
Members (Other institutions):
Jersey Liang (University of Michigan), Hiroko Akiyama (The University of Tokyo), Ikuko Sugawara (Musashino University), Hidehiro Sugisawa (J. F. Oberlin University), Yoko Sugihara (Tokyo Metropolitan University), Yoshimi Tsuda (Waseda University), Atsuhiro Yamada (Keio University), Shohei Okamoto (University of Tsukuba), Takeshi Nakagawa (Osaka University), Satoshi Seino (Yamagata University), Ken Harada (Jissen Women's University)
Nationwide representative sample of older Japanese, Long-term longitudinal study, Aging, Health, Social relationships, Socioeconomic disparities, Birth cohort, Older-old, Data archive
This project (JAHEAD: Japanese Aging and Health Dynamics) started as a collaboration between the Tokyo Metropolitan Institute of Gerontology and the University of Michigan in the late 1980s, and has been continued for over 30 years through the participation of researchers at the University of Tokyo and other institutions. The history of this long-term longitudinal study and a list of publications are available on the JAHEAD website.
The first wave of the survey was conducted in 1987 with older Japanese aged 60 and over who were randomly selected nationwide. Thereafter, they have been followed up every 3-6 years until Wave 11 in 2024, with the addition of new participants in Waves 2 (1990), 4 (1996), 8 (2012), and 10 (2021). Each wave survey was conducted by home-visit interview.
JAHEAD survey data have the following characteristics: 1) nationwide representative sample of Japanese older adults, 2) rich information on various aspects of health and lives in older age gained through face-to-face interviews (e.g., physical and mental health, family, friends and neighbors, employment, social participation, health behavior, use of medical/care services, financial status, etc.), 3) long-term longitudinal data with multiple waves, 4) sampling design that allows us to focus on older-old adults (i.e., a large-scale sample aged 70 years and over was added in 1999), and 5) permits the comparison of multiple birth cohorts. With regard to 2), we collected objective physical performance data in Waves 8 and 9 in addition to the usual self-reported health status.
Based on analyses that make the best use of these characteristics, the following four themes are focused on:
1. Changes in health and lives and their related factors in old age
It is an important issue politically as well as academically to understand how physical, psychological, and social functioning change as people get older. We will examine not only 'average' trajectories, but also the various patterns of trajectories that are affected by individual attributes, such as socioeconomic status. Moreover, our focus will be on the differential impact of the factors on health and well-being by gender and age, and also by birth cohort, time, and regions as below.
2. Changes across periods and birth cohorts among older adults
Because the employment, family, and other circumstances of older adults and their attitude to them have changed significantly in the past decades, there is uncertainty as to the extent to which findings from the earlier waves are applicable to older adults these days. Therefore, we will further promote research focusing on how age-related changes in psychological, social, and physical resources as well as predictors of health and well-being (e.g., life satisfaction) differ by survey year and birth cohort. For this purpose, new participants aged 60-92 years were added in 2012 (Wave 8) and 2021 (Wave 10).
Regarding period effects, one of the critical issues is the impact of the COVID-19 pandemic on the health and lives of older adults. The tenth wave survey was conducted during the pandemic. Through the follow-up surveys, i.e., Waves 11 and after, we will examine the impact of this historical event from various aspects, including how the cohort that experienced the pandemic is different from the previous cohorts.
3. Research on regional differences
The JAHEAD participants are a representative sample randomly selected from all over Japan, which makes the data suitable for clarifying the characteristics of "Japanese older adults". Meanwhile, there is great regional diversity within Japan; variations across regions may be observed not only in older adults' health and lives, but also in the predictors of health and well-being. Analyses will be performed where regional-level attributes in addition to person-level attributes are considered (e.g., multi-level analysis).
One of the most important regional-level attributes is the level of urbanization. For example, we found that the tendency for older adults living alone to report more depressive symptoms than those living with someone was more pronounced in less urbanized municipalities (Kobayashi et al., 2023). It is expected that comparisons between regions with different levels of urbanization will provide a clearer picture of older adults living in metropolitan areas.
4. Archiving data and promotion of secondary analysis
We have deposited the anonymous microdata in the University of Tokyo's SSJDA (Social Science Japan Data Archive), which is the largest archive of social science data in Japan. As of April 2025, Waves 1-8 (1987-2012) are already open to researchers other than JAHEAD members as the National Survey of the Japanese Elderly, and Wave 9 (2017) is being prepared for release. By archiving data, we can keep valuable data safe and also contribute to academic research by providing opportunities for secondary analysis by young researchers. We are increasing our efforts to facilitate secondary analysis in such ways as holding workshops.
The full list of publications is available on the JAHEAD website.
