Differential associations between physical frailty and aspects of well-being in community-dwelling older adults

Japan's aging population is rapidly increasing, particularly those aged ≥85 years. In gerontology and geriatric medicine, physical frailty is a significant focus, with various factors being studied.^{1, 2} In contrast, aging itself is the primary cause of frailty, meaning everyone is at risk of becoming frail as they grow older.³ Therefore, it is crucial to maintain high levels of well-being despite physical frailty.

Well-being can be categorized in various ways,⁴ notably distinguishing emotional and cognitive aspects. The emotional aspect involves feelings of enjoyment or pleasure, whereas the cognitive aspect refers to life satisfaction, including short-term satisfaction with daily life and long-term overall life satisfaction. The question arises: Which aspects of well-being are more likely to be sustained despite physical frailty?

To investigate this, we analyzed the data from the National Institute for Longevity Sciences-Longitudinal Study of Aging,⁵ which was approved by the Ethics Committee at the National Center for Geriatrics and Gerontology (No. 1665-3). Participants were 964 older adults aged 65–95 years from the ninth wave of the National Institute for Longevity Sciences-Longitudinal Study of Aging (October 2018–February 2022), with at least one previous survey of the National Institute for Longevity Sciences-Longitudinal Study of Aging. The average age was 74.70 years (standard deviation [SD] 6.96), 52.59% were men, and the average education was 12.44 years (SD 2.63). The Cardiovascular Health Study frailty score (see below) averaged 1.13 (SD 1.00). Physical frailty was assessed using the modified Cardiovascular Health Study criteria.⁶ Well-being was assessed using three items: enjoyment with daily life, measured by a Center for Epidemiologic Depression Scale item⁷: “I enjoy my daily life” (4-point scale); satisfaction with daily life, evaluated by another Center for Epidemiologic Depression Scale item⁷: “I am satisfied with my daily life” (4-point scale); and satisfaction with overall life, determined by a Life Satisfaction Index-K item⁸: “Are you satisfied with your life as a whole when you look back on it?” (3-point scale). The three well-being scores were converted to T-scores (mean 50, SD 10). To examine the relationship between physical frailty and well-being, and its age variation, we used general linear models with the three well-being indicators as outcomes and physical frailty (robust, pre-frail, frail), age groups (65–74 years, 75–84 years, ≥85 years) and their interaction as predictors, including sex and education level as covariates.

For all well-being indicators, the main effect of age was not significant. However, the main effect of physical frailty was significant for all indicators (F = 10.62, P < 0.001; F = 8.14, P < 0.001; F = 4.32, P = 0.01, respectively). Importantly, the interaction between age group and physical frailty was significant for enjoyment with daily life and satisfaction with overall life (F = 2.42, P = 0.047; F = 2.51, P = 0.040). To investigate the simple main effects of physical frailty status by age group, post-hoc analyses were carried out (Fig 1). These analyses revealed that for enjoyment with daily life and satisfaction with overall life scores decreased with progressing physical frailty in the age groups 65–74 years (both trend P < 0.001) and 75–84 years (trend P < 0.001; trend P = 0.016). However, no such relationship was observed for those aged ≥85 years.

In summary, our data from community-dwelling older adults aged 65–95 years show that the associations between physical frailty and well-being indicators vary depending on the aspects of well-being. Satisfaction with everyday life was associated with physical frailty across all age groups, possibly due to physical health issues. Conversely, although feelings of enjoyment with daily life and overall life satisfaction are related to physical frailty in the young-old and old age groups, these associations might not persist in advanced old age; that is, old-old adults can maintain feelings of enjoyment and overall life satisfaction even when they are frail. It should be noted that single items, selected from existing scales based on their meanings, were used as indicators of three well-being aspects for easier assessment in community and nursing care settings. Further research is needed to validate their reliability.

The recent gerontological perspective has emphasized promoting “happy longevity” as well as healthy longevity, as the time spent in reduced health increases in a super-aged society. Gondo⁹ highlighted centenarians' views: “When I was a child, I had the enjoyment of childhood, but older people have their own enjoyment.” Erikson¹⁰ stated that the challenge in old age is achieving integrity, questioning whether the individual has lived a meaningful and satisfying life. Thus, enjoyment with daily life and overall life satisfaction are important aspects of well-being in old age, especially when facing significant functional decline. In medical and nursing care for adults aged ≥85 years, assessing and enhancing these aspects of well-being might be key to promoting happy longevity.

The authors declare no conflict of interest.

YN contributed to the conception and design of the study, data analysis, and interpretation of results. SK, MT and CT were responsible for data collection and manuscript drafting. RO provided critical revisions to the manuscript. All authors read and approved the final version of the manuscript and, agreed to be accountable for all aspects of the work.