皆川 友香

ABSTRACT Extensive literature exists on the physical health of the Japanese population whereas relatively little is known about their mental health. Moreover, most studies have assessed physical and mental health separately, and this further confounds the relationship between the two. Using the concept of health expectancy, this study investigated the trends in the relationship between physical and mental health among Japanese men and women aged 20 years or more between 2010 and 2022. Psychological distress, based on the Comprehensive Survey of Living Conditions, was used as an indicator of mental health. We employed Sullivan's method to estimate the length of life with or without distress of varying degrees. Our results showed substantial improvements in distress‐free life expectancy for both genders during the study period. Younger people have gained more distress‐free years than their older counterparts, placing older individuals, especially men, at an increased risk of psychological distress. These findings contribute to the literature on longevity in Japan by quantifying the role of mental health in the population's overall health. Given the recent increase in mental health problems, greater policy emphasis on the relationship between physical and mental health status is required.

Abstract Background The European Union has used Healthy Life Years (HLY) as an indicator to monitor the health of its aging populations. Scholarly and popular interest in HLY across countries has grown, particularly regarding the ranking of countries. It is important to note that HLY is based on self-assessments of activity limitations, raising the possibility that it might be influenced by differences in health reporting behaviours between populations, a phenomenon known as differential item functioning (DIF). Methods We estimated DIF-adjusted HLY at age 50 for Belgium, France, Germany, Greece, Italy, the Netherlands, Spain, and Sweden to determine the extent to which differences in HLY might be influenced by reporting heterogeneity across countries. We used anchoring vignettes, taken from the 2004 Survey of Health, Ageing and Retirement in Europe, to estimate DIF-adjusted prevalence rates of activity limitations measured by the Global Activity Limitations Indicator (GALI). The Sullivan method was used to calculate DIF-adjusted HLY. Results Changes in HLY before and after adjustment ranged from a 1.20-year decrease for men in Italy to a 1.61-year increase for women in Spain. Adjustment for DIF produced changes in the rankings of the countries by HLY, with upward and downward movements of up to three positions. Conclusion Our results show that DIF is likely to affect HLY estimates, thereby posing a challenge to the validity of comparisons of HLY across European countries. The findings suggest that HLY should be used to monitor population health status within a country, rather than to make comparisons across countries.

Abstract Background and Objectives Existing research has suggested that older adults in Japan enjoy phenomenal physical health status, but they have poor subjective well-being (SWB). Limited empirical evidence exists, however, on how physical health and SWB intersect and are linked to the lives of older men and women in Japan. Using the concept of health expectancy, this study examines the role of SWB, as measured by life satisfaction, in the mortality and morbidity experiences of Japanese adults 65 years old and older. Research Design and Methods We used the nationally representative Nihon University Japanese Longitudinal Study of Aging (NUJLSOA), 1999-2009. Our measurement of morbidity is disability, based on difficulty in activities in daily living (ADLs) and instrumental ADLs (IADLs). We use the Interpolation of Markov Chains (IMaCh) approach to compute life expectancy (LE), LE without disability (active LE), and LE with differing severity of disability for those who are satisfied with life and for those who are not. Results We documented significant differences in LE and active LE by the state of life satisfaction among older adults in Japan. Men and women who are satisfied with life are expected to live longer and spend more years without having disability compared to those who are not satisfied. We found no differences in the length of life with disability of differing severity by the state of life satisfaction. Discussion and Implications Our results highlight the important role of SWB at older ages in Japan, since it is directly related to the physical health of its aging population. Fully understanding the health of the older population requires research that focuses on both objective and subjective dimensions of well-being.