ORIGINAL ARTICLE: EPIDEMIOLOGY, CLINICAL PRACTICE AND HEALTH Association between the older adults’ social relationships and functional status in Japan Kumi Watanabe, 1 Emiko Tanaka, 1 Taeko Watanabe, 2 Wencan Chen, 1 Bailiang Wu, 3 Sumio Ito, 4 Rika Okumura 4 and Tokie Anme 1 1 Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, 2 Japan University of Health Sciences, Satte, Saitama and 3 Social Welfare Corporation Hakuzyukai, and 4 Department of Public Welfare, Tobishima, Aichi, Japan Aim: Previous studies have shown that social relationships positively contribute to the functioning of older adults. How- ever, the particular aspects of social relationships that are most predictive remain unknown. Consequently, the current study aimed to clarify what elements of social relationships impacted the maintenance of functioning among older adults. Methods: The present study used baseline data collected in 2011, and follow-up surveys were carried out 3 years later. Participants included individuals aged 65 years or older who lived in a suburban community in Japan. A total of 434 participants met inclusion criteria for the study and were included in analysis. The Index of Social Interaction measure consists of five subscales (independence, social curiosity, interaction, participation and feeling of safety), and was used to assess the multiple elements of social relationships. Results: After controlling for age, sex, disease status and mobility in 2011, the results showed that the social curiosity subscale was significantly associated with functional status after 3 years (OR 1.29, 95% CI 1.02–1.63). Other Index of Social Interaction subscales were non-significant. Conclusions: The current study suggests that interaction with environment and multifaceted social relationships have the strongest impact on functional ability for older adults in Japan. Geriatr Gerontol Int 2016; ••: ••–••. Keywords: aging, elderly, functioning, prevention, social relationships. Introduction Worldwide, the age of the population has begun to accel- erate, and its rate is expected to continue to increase during the next half century in low- and middle-income countries, as well as developed countries. 1,2 As the aging population will also increase the economic burden and cause serious social concerns in the near future, effective prevention to maintain good function among older adults is an urgent global issue. In terms of preventing decline in functional status, several factors such as age, high medica- tion use, weight loss, smoking, and social activity have been reported as risk factors. 3,4 In particular, social relationships have received a high level of attention. The Japanese Ministry of Health has driven the long- term care system since 2000. In this system, promoting elderly social activity and participation were added as key prevention concepts. This policy was based on the results of numerous studies reporting that social relationships including social participation and activities affect mainte- nance of physical and mental health. Prior studies have shown that social relationships can positively contribute to longevity. 5–7 Specifically, social relationships are associated with health indicators. These studies have evaluated various social relationships in sev- eral ways. For example, a prospective study showed that physical function was associated with social activity partic- ipation, 8 engagement in paid work, 9 structural network and instrumental support, 10 and that these factors were associated with daily living ability. Late life intellectual activity 11 and social activity 12,13 have also been found to have effects on cognitive function. Additionally, social leisure activity 14 and social network 15 have predictive power for dementia. Finally, social isolation and decreased social networks were also reported to be associated with a high risk of mortality 5–7 among older adults. According to Cohen, three aspects of social relation- ships have been primarily measured: (i) social integration; (ii) social interaction; and (iii) social support. 16 Although Accepted for publication 31 July 2016. Correspondence: Professor Tokie Anme PhD, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan. Email: tokieanme@gmail.com © 2016 Japan Geriatrics Society doi: 10.1111/ggi.12909 | 1 Geriatr Gerontol Int 2016