Yoshinori Fujiwara

Background: Older outpatients with chronic diseases are susceptible to muscle weakness and functional disabilities. Recently, various wearable devices have been developed to generate health lifelogs in daily life; however, data from patients with chronic diseases remain scarce. Previous studies have shown that subjective sleep efficiency assessed by self-questionnaires is associated with grip strength, but whether objective sleep efficiency detected by wearable devices is associated with physical function and body composition remains unclear. Objective: The aim of this study is to clarify the association between sleep duration, sleep efficiency estimated by wearable watch, grip strength, frailty, and sarcopenia in outpatients with predominantly cardiometabolic diseases and the influence of diabetes as part of the Smart Watch Innovation for Geriatrics and Gerontology (SWING-Japan) project. Methods: In this cross-sectional study, the wrist-worn device Silmee 22 was used in an outpatient clinic of an acute care facility for 7‐90 nights for the analyses, and individual average sleep duration and efficiency (wearable-estimated sleep efficiency: total sleep duration/time spent in bed) were calculated. Low grip strength was defined as P =.006, 245 vs 276 min, P =.04). Wearable-estimated sleep efficiency was not associated with frailty, low muscle mass, or slow walking speed. After adjusting for the above variables, low wearable-estimated sleep efficiency, but not low sleep duration, was associated with a risk of lower grip strength (odds ratio 1.04, 95% CI 1.01‐1.08; P =.02) by 1 percentage point decrease in wearable-estimated sleep efficiency. This association was observed in patients with diabetes (odds ratio 1.05, 95% CI 1.002‐1.093; P =.04). However, no significant interaction was observed. Conclusions: In older patients with cardiometabolic diseases, objective low wearable-estimated sleep efficiency evaluated with wrist-worn wearable devices was associated with low muscle strength. No evidence was found to suggest that the strength of this association differed according to diabetes status. Longitudinal studies are needed to clarify the long-term association between low wearable-estimated sleep efficiency and muscle strength in this population.

Background: Epidemiological studies have suggested a possible association between tooth loss and dementia, yet evidence regarding mild cognitive impairment (MCI) remains limited. Objective: We examined the association between the number of remaining teeth and functional tooth units (FTUs) and the prevalence of MCI. Methods: A total of 8697 adults aged 20–95 years (3786 men and 4911 women) were included. Dental status was assessed visually, excluding third molars. MCI was defined as a score of less than 26 on the Japanese version of the Montreal Cognitive Assessment. Participants were categorized into five groups based on the FTUs of natural teeth (n-FTUs) and total FTUs: n-FTUs ≥10; n-FTUs 6–9 and total FTUs ≥10; n-FTUs 6–9 and total FTUs p for trend <0.0001). Compared with having n-FTUs ≥10, having n-FTUs <6 and total FTUs ≥10, and having n-FTUs <6 and total FTUs <10 were independently associated with a higher prevalence of MCI. There was no association between having 6–9 n-FTUs, regardless of total FTUs, and the prevalence of MCI. Conclusions: Even when occlusal function is maintained through prosthodontic restorations, a reduced number of natural teeth is independently associated with MCI, underscoring the importance of preserving natural dentition for maintaining cognitive health.

Amid rapid population aging, declining fertility, and a shrinking workforce, employment in later life has become a critical issue in Japan. Older adults are no longer viewed solely as care recipients; many remain engaged in paid work, making employment a key form of social participation. This review synthesizes epidemiological evidence on the health benefits, challenges, and future directions of late‐life employment, drawing on the authors' previous studies and domestic and international cohort research from a health and welfare policy perspective. Longitudinal evidence indicates that continued employment is associated with reduced mortality, better self‐rated health, preserved cognitive function, and maintained activities of daily living. However, these benefits vary by sex, employment type, and frailty status. Notably, full‐time employment may offer protective effects even among frail older adults, particularly in reducing risks related to dementia and physical decline, whereas irregular or sporadic work provides limited benefits. The motivation and meaning of work also play a crucial role. Employment driven solely by financial necessity is linked to poorer health outcomes and greater social isolation, while nonfinancial motivations—such as maintaining health, purpose in life, and social contribution—are associated with more favorable outcomes. Finally, the study underscores the importance of community‐based intermediaries and emerging approaches such as social prescribing to connect older adults with meaningful, ability‐appropriate work. Effective support requires integrating employment assistance with frailty assessment, safety management, and multidisciplinary coordination.

Background: Increasing life expectancy has increased focus on the health-related consequences of aging, such as sarcopenia and frailty. Given the prevalence of these conditions among older individuals and the frequent resulting long-term care needs, early detection and intervention are crucial. Objective: This study aimed to validate a novel smartphone-based system measuring acceleration during the sit-to-stand movement to detect sarcopenia and frailty. Methods: Participants were 587 individuals from the Otassha study cohort who underwent health assessments in 2023, of whom 569 (96.9%) completed 2 supervised sit-to-stand trials while holding a smartphone on the lower abdomen. Sarcopenia and frailty were diagnosed using the Asian Working Group for Sarcopenia 2019 criteria and the revised Japanese Cardiovascular Health Study criteria, respectively. Peak force, rising time (T1), and stabilization time (T2) were extracted from acceleration signals, and reproducibility was examined using the intraclass correlation coefficient (ICC(2,1)). Predictive models were developed using elastic net penalized logistic regression, and model performance was evaluated using 500 bootstrap resamples. Benchmark models using age and sex, walking speed, and grip strength were also constructed for comparison. Results: Sarcopenia and frailty were identified in 16.7% (95/569) and 9% (51/569) of the participants, respectively. Peak force demonstrated excellent reliability (ICC=0.863), whereas T1 and T2 showed lower reproducibility (ICC<0.30). For sarcopenia, the smartphone model achieved a bootstrap area under the receiver operating characteristic curve (AUC) of 0.800 and an optimism-corrected AUC of 0.781 (95% CI 0.733‐0.826), outperforming walking speed (0.663) and age and sex (0.656) and ranking second only to grip strength (0.845). For frailty, the smartphone model showed moderate discrimination, with an optimism-corrected AUC of 0.659 (95% CI 0.587‐0.736), exceeding age and sex (0.604), whereas walking speed remained the strongest predictor (0.751). Conclusions: Smartphone-derived sit-to-stand acceleration provides a practical and scalable approach for screening for sarcopenia and frailty in community-dwelling older adults. While traditional indicators such as grip strength and walking speed remain the most accurate predictors, smartphone-based measurements offer meaningful complementary information and may support large-scale functional screening and early detection initiatives in superaged societies.

Japan is experiencing unprecedented population aging, with adults' aged 65 years and older accounting for nearly 30% of its total population. In this context, employment has attracted increasing attention as an important form of social participation in later life. However, despite increased labor force participation among older adults, suitable employment opportunities remain limited. Moreover, Japan is simultaneously facing a serious workforce shortage in the long‐term care sector, raising concerns about care system sustainability in super‐aging societies. This review aims to not only provide an overview of later‐life employment in Japan but also introduce the older assistant care worker model as a concrete and socially acceptable form of older adults' employment in long‐term care settings. Drawing on nationwide surveys of geriatric health service facilities in Japan, this review examines how older adults' involvement in non‐professional, peripheral tasks can generate multidimensional benefits. The findings indicate that the older assistant care worker model—adopted across prefectures—reflects its practical feasibility and social acceptance within geriatric health service facilities. For older assistant care workers, employment was associated with perceived health maintenance, meaningful use of time, and enhanced social participation and social connection, which, in turn, were associated with lower emotional exhaustion. For care staff, the presence of older assistant care workers was related to reduced workload and lower burnout risk. Overall, the older assistant care worker model represents an age‐friendly employment approach that benefits older adults, care staff, and care facilities, potentially contributing to sustainable long‐term care systems in aging societies.

Aim: Dynapenia—loss of muscle strength despite preserved muscle mass—is a clinical concern linked to functional decline in older adults. Diabetes may contribute to dynapenia; however, few studies have examined whether this association varies by sex and age. Clarifying these differences may help inform targeted prevention strategies. This study investigated the association between diabetes and dynapenia in community‐dwelling older adults in Japan, focusing on sex‐ and age‐specific differences. Methods: We conducted a cross‐sectional analysis using pooled data from four geriatric cohorts in Japan. Participants were classified into three groups: (1) established diabetes (treatment or HbA1c ≥ 6.5%), (2) prediabetes (HbA1c 5.7%–6.4%, no treatment), and (3) non‐diabetes (HbA1c < 5.7%, no treatment). Dynapenia was defined per Asian Working Group for Sarcopenia 2019 cutoffs as low grip strength with preserved muscle mass. Sex‐stratified logistic regression examined the association between diabetes status and dynapenia, adjusting for age, body fat, comorbidities, lifestyle factors, and cohort. Analyses were also stratified by age group (65–74 and ≥ 75 years). Results: Among 3085 participants (34.8% men; median age: 70 years), the prevalence of dynapenia was 13.0% in both sexes. In women, dynapenia prevalence increased with glycemic status; adjusted ORs were 1.32 (95% CI: 0.97–1.78) for prediabetes and 1.86 (1.27–2.71) for established diabetes. Stratified analyses showed significant associations in men aged 65–74 and women aged ≥ 75. Conclusions: Diabetes was associated with dynapenia, with distinct patterns by sex and age. Targeted strategies may be needed for younger‐old men and older‐old women with diabetes.

Background: The new position paper on the definition and diagnosis of respiratory sarcopenia defines respiratory sarcopenia as a decrease in respiratory muscle strength and mass. It recommends using a decrease in limb muscle mass as a substitute for respiratory muscle mass, which is difficult to measure, and recommends that such cases be diagnosed as “probable respiratory sarcopenia” with appropriate interventions. This study aimed to determine the physical characteristics of older adults with probable respiratory sarcopenia based on current criteria. Methods: A total of 496 community‐dwelling older adults were enrolled in this study, completing an evaluation of respiratory and physical function in 2023 as part of a comprehensive health check‐up program called the Otassha study. The respiratory and physical functions, comorbidities, instrumental activities of daily living, and lifestyles of the participants were measured. “Probable respiratory sarcopenia” was compared to non‐respiratory sarcopenia with respect to respiratory and physical functions. Probable respiratory sarcopenia was determined using low maximal mouth pressure (< 80% of predicted value) and low appendicular skeletal muscle mass (ASM)/height ² (7.0 kg/m ² for men and 5.7 kg/m ² for women). The association between probable respiratory sarcopenia (as the independent variable) and physical and peak expiratory flow rate (PEFR) (as dependent variables), adjusted for covariates, was evaluated using a multivariate linear regression model. A 2:1 matched pair of individuals with non‐respiratory sarcopenia and probable respiratory sarcopenia was compared using propensity score matching (PSM) to account for confounders. Results: The prevalence of probable respiratory sarcopenia was 33 out of 185 (17.8%) in men and 65 out of 311 (20.9%) in women. Grip strength, knee extension strength, and PEFR were significantly associated with probable respiratory sarcopenia ( p = 0.001 to p < 0.01). In the PSM data set, compared to non‐respiratory sarcopenia, those with probable respiratory sarcopenia showed significantly lower values for respiratory function, grip strength, and knee extension strength, cognitive function, as well as a higher prevalence of whole‐body sarcopenia ( p = 0.028 to p < 0.001). Conclusion: Probable sarcopenia is characterized by low limb muscle strength and impaired respiratory and physical function. Understanding this aspect of suspected respiratory sarcopenia can aid in early detection and treatment management, leading to improved future health outcomes.

BACKGROUND Frailty is defined as increased vulnerability to stress. Although frailty is typically associated with older age, it can also affect younger population. In 2024, we launched the Osaka-Settsu Study in Japan. This population-based prospective study aimed to identify the risk factors for lifestyle-related diseases and care given and contribute to precision health care. OBJECTIVE This cohort profile paper describes the study design, the demographics of the participants, and the prevalence of frailty. METHODS A self-administered questionnaire survey was mailed to registered residents aged ≥ 18 years in Settsu City from February to June 2024. The survey asked the participants about physical activity, nutritional status, well-being, and frailty. The participants will be followed up for the incidence of lifestyle-related diseases, need for support/long-term care certification, emergency transportation, and migration. RESULTS Of the 71,680 self-administered questionnaires distributed, 13,282 were completed. The mean age (standard deviation) were 62.1 (17.6) and 60.7 (18.4) years for females and males, respectively. The proportion of robust, prefrail, and frail were 18.5%, 65.5%, and 16.0% in females and, 18.7%, 63.8%, and 17.5% in males, respectively, based on the criteria of the Fried index. The prevalences of frailty in both female and male was 10% across all age groups. CONCLUSIONS Frailty is prevalent even in younger adults. This study is planned to collect information on vital status and conducted follow-up surveys to identify the predictors of functional decline across the course of life. This study provides valuable evidence for the development of strategies to extend a healthy lifespan.

Aim: The Japan Science and Technology Agency Index of Competence (JST‐IC) was developed to measure competence at much higher levels than the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG‐IC), which evaluates higher‐level functional capacity necessary for independent living. This study explored the JST‐IC aging trajectories and their associations with instrumental activities of daily living (IADL) impairment in community‐dwelling older Japanese individuals. Methods: Participants were 665 adults who responded to the 2014 baseline survey and at least one follow‐up survey (2015–2019) of the Otassha study. The JST‐IC and TMIG‐IC aging trajectories were identified using group‐based trajectory modeling. The association with nine‐year IADL impairment onset was investigated using Cox proportional hazards models. Results: Three JST‐IC trajectory groups were identified: high (29.5%), medium (53.1%), and low (17.3%), with scores decreasing by one to two points with increasing age over the follow‐up period. High‐stable (50.6%), late‐onset decrease (41.1%), and early‐onset decrease (8.3%) TMIG‐IC trajectory groups were identified with a one‐ to three‐point decrease in late‐ and early‐onset groups. The low JST‐IC trajectory group had an adjusted hazard ratio of 2.90 (95% confidence interval, 1.60–5.24) for IADL impairment (reference: high group). Low technology usage, information practices, and social engagement trajectories were significantly associated with IADL impairment. Conclusions: The JST‐IC scores gradually declined in all groups, even among those who maintained their TMIG‐IC scores. The low JST‐IC trajectory group—particularly low technology usage, information practices, and social engagement—was associated with the onset of IADL impairment.