Machine Learning-Based Prediction of Functional Disability: a Cohort Study of Japanese Older Adults in 2013-2019.

BACKGROUND: It is important to identify older adults at high risk of functional disability and to take preventive measures for them at an early stage. To our knowledge, there are no studies that predict functional disability among community-dwelling older adults using machine learning algorithms. OBJECTIVE: To construct a model that can predict functional disability over 5 years using basic machine learning algorithms. DESIGN: A cohort study with a mean follow-up of 5.4 years. PARTICIPANTS: We used data from the Japan Gerontological Evaluation Study, which involved 73,262 people aged ≥ 65 years who were not certified as requiring long-term care. The baseline survey was conducted in 2013 in 19 municipalities. MAIN MEASURES: We defined the onset of functional disability as the new certification of needing long-term care that was ascertained by linking participants to public registries of long-term care insurance. All 183 candidate predictors were measured by self-report questionnaires. KEY RESULTS: During the study period, 16,361 (22.3%) participants experienced the onset of functional disability. Among machine learning-based models, ridge regression (C statistic = 0.818) and gradient boosting (0.817) effectively predicted functional disability. In both models, we identified age, self-rated health, variables related to falls and posture stabilization, and diagnoses of Parkinson's disease and dementia as important features. Additionally, the ridge regression model identified the household characteristics such as the number of members, income, and receiving public assistance as important predictors, while the gradient boosting model selected moderate physical activity and driving. Based on the ridge regression model, we developed a simplified risk score for functional disability, and it also indicated good performance at the cut-off of 6/7 points. CONCLUSIONS: Machine learning-based models showed effective performance prediction over 5 years. Our findings suggest that measuring and adding the variables identified as important features can improve the prediction of functional disability.

Physical performance reference values for Japanese oldest old: a SONIC study.

BACKGROUND: The oldest old, defined as those aged 90 or over, is now the fastest-growing population sector. This study aimed to determine reference values for several physical performance measures (PPMs) among 90-year-olds using internationally standardized measurements and to clarify the characteristics of these indices by comparing their results for 90-year-olds with those for older people 70 and 80. METHODS: We used the Septuagenarians, Octogenarians, and Nonagenarians Investigation with Centenarians (SONIC) study data from 2010 to 2018. The study subjects were 70, 80, and 90-year-olds in the target area eligible to participate in the venue. Excluding those certified for long-term care, the final number of eligible persons is 70s cohort 1000 (2010), 80s cohort 973 (2011), and 90s cohort 690. 90s cohort only consisted of three survey waves: 2012, 2015, and 2018. We used hand grip strength and score on the Short Physical Performance Battery (SPPB) for our physical performance measurements. In addition, we statistically analyzed sex and age differences. RESULT: The simple mean ± standard deviation (SD) for the 90-year-old respondents were in men, 24.1 ± 5.4 kg in hand grip strength, 0.80 ± 0.22 m/s in usual gait speed, 17.2 ± 6.73 s in 5times chair stand, 5.89 ± 4.42 s in tandem balance, and 8.3 ± 2.2 in SPPB respectively and in women, 14.4 ± 4.0 kg in hand grip strength, 0.72 ± 0.20 m/s in usual gait speed, 17.8 ± 7.89 s in 5times chair stand, 4.72 ± 4.35 s in tandem balance, and 7.5 ± 2.4 in SPPB, respectively. For all PPMs, the age 90 cohort was statistically significantly different from the age 70 and 80 cohorts (all trends P <  0.001). Hand grip strength decreased with a similar gradient with age cohort increase of 10 years for both sexes. In contrast, SPPB lower limb score showed a larger drop between the age 80 and 90 cohorts than between the age 70 and 80 cohorts. We also constructed sex-specific appraisal standards according to quintiles. CONCLUSIONS: Our study yielded inclusive sex-specific reference values and appraisal standards for major physical performance measures not certified as requiring long-term care, community-dwelling, oldest old Japanese. The characteristics of age-related decline in physical performance differed between the upper and lower extremity assessments.

Potential causal effect of physical activity on reducing the risk of dementia: a 6-year cohort study from the Japan Gerontological Evaluation Study.

BACKGROUND: The causal effect of physical activity on reducing dementia risk has been questioned due to the possibility of reverse causation. This study examined the potential causal effects of physical activity on reducing dementia risk using residency in a snowy area as an instrumental variable (IV) representing the physical activity of older adults. METHODS: We used cohort data from the Japan Gerontological Evaluation Study, a longitudinal cohort enrolling people aged 65 or older who were physically and cognitively independent in 2013; study participants were followed for an average of 5.7 years. Participants in the present study included 73,260 individuals living in 19 municipalities in Japan. Physical activity was measured by self-report questionnaires and the incidence of dementia was ascertained by linking participants to the public registries of long-term care insurance. IV estimation was obtained from a piecewise Cox proportional hazard model using a two-stage regression procedure. RESULTS: During the study period, we ascertained 8714 cases (11.9%) of dementia onset. In the IV analysis, we found that the frequency of physical activity per week was negatively associated with dementia risk, though the association weakened over time (Year 1: hazard ratio = 0.53, 95% confidence interval: 0.39-0.74; Year 4: 0.69, 0.53-0.90; Year 6: 0.85, 0.66-1.10). CONCLUSIONS: Our IV analysis indicated a potential causal effect of physical activity on reducing dementia risk that persisted for at least 4 years of follow-up. Thus, we conclude that physical activity should be recommended for older adults to reduce dementia risk.

End-of-Life Activities Among Community-Dwelling Older Adults in Japan.

This study explored end-of-life (EOL) activities among community-dwelling Japanese older adults and the relationships between EOL activities and related variables. One hundred twenty-three older adults (38 men, 87 women; mean age = 72.54 years) who attended EOL seminars were surveyed regarding EOL activities, attitudes toward death, and mental health status. Cluster analysis of EOL activities revealed three clusters: Planning (e.g., had planned own funeral arrangements), Preference (e.g., had talked about EOL care with their family), and Preparation (e.g., already written their will). The number of EOL-related events attended was positively correlated with Preparation, while fear of death was negatively associated with Preference. Older adults with bereavement experience had higher Planning and Preparation scores than those without such experience.

The Asian working group for sarcopenia's new criteria updated in 2019 causing a change in sarcopenia prevalence in Japanese older adults requiring long-term care/support.

[Purpose] The Asian Working Group for Sarcopenia (AWGS) criteria were recently updated. However, whether these changes would result in a difference in sarcopenia prevalence was unclear. We therefore focused on Japanese older adults who required long-term care/support and determined the differences in sarcopenia prevalence between the new and old criteria. [Participants and Methods] This cross-sectional study included 161 Japanese older adults aged ≥65 years who required long-term care/support along with ongoing daycare. Handgrip strength, usual gait speed, and skeletal muscle mass index were measured. We analyzed the difference in sarcopenia prevalence between the 2019 and 2014 AWGS criteria using the McNemar test. [Results] The overall sarcopenia prevalence rates were 60.2% and 53.4%, and the prevalence rates of sex-specific sarcopenia were 63.6% and 55.7% among males and 56.2% and 50.7% among females when the 2019 and 2014 AWGS criteria were used, respectively. Overall, males exhibited a significantly higher prevalence with the new than criteria than with the old. [Conclusion] With the 2019 AWGS criteria, more older males who required long-term care/support were diagnosed as having sarcopenia. Conversely, the sarcopenia diagnosis in females statistically remained unchanged. Thus, a mismatch might exist between the two criteria regarding sarcopenia prevalence in males.

Association of Statin Use with Dementia Risk Among Older Adults in Japan: A Nested Case-Control Study Using the LIFE Study.

Background: Previous studies have shown a possible association between statin use and a decreased risk of dementia, but the association has not been sufficiently established, especially in the super-aging society of Japan. Objective: This study aimed to determine the association between statin use and the risk of dementia among Japanese participants aged> =65 years old. Methods: Data from the Longevity Improvement and Fair Evidence (LIFE) Study were utilized, including medical and long-term care (LTC) claim data from 17 municipalities between April 2014 and December 2020. A nested case-control study was conducted with one case matched to five controls based on age, sex, municipality, and year of cohort entry. We used a conditional logistic regression model to calculate the odds ratios (ORs) and 95% confidence intervals (95% CIs). Results: This study included 57,302 cases and 283,525 controls, with 59.7% of the participants being woman. After adjusting for potential confounders, statin use was associated with a lower risk of dementia (OR, 0.70; 95% CI: 0.68-0.73) and Alzheimer's disease (OR: 0.66; 95% CI: 0.63-0.69). Compared with non-users, the ORs of dementia were as follows: 1.42 (1.34-1.50) for 1-30 total standardized daily dose (TSDD), 0.91 (0.85-0.98) for 31-90 TSDD, 0.63 (0.58-0.69) for 91-180 TSDD, and 0.33 (0.31-0.36) for >180 TSDD in dose-analysis. Conclusions: Statin use is associated with a reduced risk of dementia and Alzheimer's disease among older Japanese adults. A low cumulative statin dose is associated with an increased risk of dementia, whereas a high cumulative statin dose is a protective factor against dementia.

Statin use and risk of Parkinson's disease among older adults in Japan: a nested case-control study using the Longevity Improvement and Fair Evidence study.

The association between statin use and the risk of Parkinson's disease remains inconclusive, particularly in Japan's super-ageing society. This study aimed to investigate the potential association between statin use and the risk of Parkinson's disease among Japanese participants aged ≥65 years. We used data from the Longevity Improvement and Fair Evidence Study, which included medical and long-term care claim data from April 2014 to December 2020 across 17 municipalities. Using a nested case-control design, we matched one case to five controls based on age, sex, municipality and cohort entry year. A conditional logistic regression model was used to estimate the odds ratios with 95% confidence intervals. Among the 56 186 participants (9397 cases and 46 789 controls), 53.6% were women. The inverse association between statin use and Parkinson's disease risk was significant after adjusting for multiple variables (odds ratio: 0.61; 95% confidence interval: 0.56-0.66). Compared with non-users, the dose analysis revealed varying odds ratios: 1.30 (1.12-1.52) for 1-30 total standard daily doses, 0.77 (0.64-0.92) for 31-90 total standard daily doses, 0.62 (0.52-0.75) for 91-180 total standard daily doses and 0.30 (0.25-0.35) for >180 total standard daily doses. Statin use among older Japanese adults was associated with a decreased risk of Parkinson's disease. Notably, lower cumulative statin doses were associated with an elevated risk of Parkinson's disease, whereas higher cumulative doses exhibited protective effects against Parkinson's disease development.

Frailty and Diminished Human Relationships Are Associated with Poor Sleep Quality in Japanese Older Adults: A Cross-Sectional Study.

The purpose of this study was to examine the association between sleep quality, frailty, and human relationships in Japanese older adults (aged 65 years and above, excluding those certified as requiring long-term care). This cross-sectional study used a questionnaire survey to gather demographic information, data on frequency of conversation and conversation partners, and employed the following validated instruments: Kihon Checklist (KCL), a Japanese instrument used to determine the care needs and frailty of older adults; the Dysphagia Risk Assessment for Community-Dwelling Elderly (DRACE) scale; Japanese versions of Pittsburgh Sleep Quality Index (PSQI-J); the Geriatric Depression Scale-15 (GDS-15-J); and the University of California Los Angeles Scale (UCLA-J), an instrument to assess loneliness in older adults. The 500 respondents were divided into two groups based on sleep quality (PSQI-J): low sleep quality group (n = 167, 33.4%) and high sleep quality group (n = 333, 66.6%). Our analyses showed that the low sleep quality group had a KCL score of 5.55 ± 2.47, which indicated frailty. Binomial logistic regression analysis identified age, number of diseases under treatment, DRACE, GDS-15-J, and conversation frequency and discussion partner for important matters as factors (p < 0.05) associated with poor sleep quality. These factors could help enhance the detection of frailty and predictability of caregiving needs.

Characteristics associated with optimistic or pessimistic perception about the probability of contracting COVID-19: A cross-sectional study of Japanese older adults.

Introduction: Excessive optimistic perception about the probability of acquiring coronavirus disease (COVID-19) may hinder people from exercising preventive measures, whereas excessive pessimistic perception can induce psychological problems. Not much focus has been paid to this topic, and prior studies are only online surveys. We determined the characteristics of older adults with optimistic and pessimistic perceptions of the probability of contracting COVID-19. Methods: We used data from the Japan Gerontological Evaluation Study (JAGES), including 18,045 participants aged ≥ 65 years (mean age: 75.7 years) who were physically and cognitively independent. Self-reported questionnaires were sent to 11 municipalities between November 2020 and February 2021. Multinomial logistic regression was used for data analysis. Results: The characteristics of 1,596 (8.8%) participants with optimistic perception and 1,276 (7.1%) with pessimistic perception were compared with that of others (80.4%) with moderate perception. Optimism about infection probability was positively associated with older age; better perceived financial conditions but negatively associated with higher education level; trust in TV news programs, TV information programs, and government-issued newsletters; depressive symptoms; and higher levels of reciprocity. Pessimism was negatively associated with higher levels of social cohesion. In contrast, it was positively associated with engagement in paid work; trust in TV news programs, the Internet, and information from medical staff; and depressive symptoms. Conclusion: Optimistic and pessimistic perceptions about the probability of acquiring infection correlated differently with various characteristics. Thus, risk communication during a pandemic should be tailored based on specific individual characteristics.

Associations between salivary testosterone levels and cognitive function among 70-year-old Japanese elderly: A cross-sectional analysis of the SONIC study.

AIM: This cross-sectional study aimed to investigate the associations between salivary testosterone concentrations and cognitive function in 70-year-old Japanese elderly people without dementia and stroke. METHODS: Participants were 197 Japanese community-dwelling people aged 69-71 years. Their salivary samples were collected, and their cognitive function was assessed using the Japanese version of the Montreal Cognitive Assessment (MoCA-J). Participants were also administered a 10-item recall and a 24-item recognition test. The data for 179 (106 men and 73 women) individuals were analyzed, excluding individuals with a past history of stroke and dementia. Multivariate logistic regression analyses were performed after adjusting for lifestyle factors and analyzing data separately for men and women. RESULTS: MoCA-J scores showed that men with low testosterone concentrations had a significantly greater risk of low cognitive performance than those with high testosterone concentrations (adjusted odds ratio: 4.72, 95% confidence interval: 1.06-21.00), while no significant association was found in women. The 10-item recall test scores showed that higher testosterone concentrations were significantly associated with greater recall in the second trial in women (standardized beta = 0.24, P = 0.040), whereas no significant association was found in men. Salivary testosterone concentrations were positively associated with better cognitive performance in older men and women. CONCLUSIONS: The associations between salivary testosterone concentrations and cognitive function were shown by different tasks for men and women. Geriatr Gerontol Int 2022; 22: 1040-1046.

Pre-pandemic individual- and community-level social capital and depressive symptoms during COVID-19: A longitudinal study of Japanese older adults in 2019-21.

During a pandemic, it is important to know whether social capital can mitigate the risk of mental disorders, given the restrictions on social interactions. However, evidence using longitudinal data is scarce. This study examined the association between pre-pandemic social capital and depressive symptoms during COVID-19 among older adults. We used longitudinal data from the Japan Gerontological Evaluation Study (JAGES), including 8291 participants aged 65 or older who were physically and cognitively independent and not depressed at baseline. We conducted baseline and follow-up mail surveys in ten municipalities in Japan from November 2019 to January 2020 (pre-pandemic period) and from November 2020 to February 2021 (pandemic period), respectively. We measured depressive symptoms using the 15-item Geriatric Depression Scale. Social capital was measured with three validated subscales, namely, civic participation, social cohesion, and reciprocity. We performed a multilevel logistic regression analysis to examine the association. A total of 1089 (13.1%) participants newly developed depressive symptoms during the pandemic. The logistic regression showed that pre-pandemic individual-level social cohesion (odds ratio = 0.79, 95% confidence interval: 0.73 to 0.86) and reciprocity (0.89, 0.82 to 0.96) and community-level reciprocity (0.93, 0.88 to 0.98) were negatively associated with the odds of depressive symptoms. Even after adjusting for declines in social capital during the pandemic, the observed associations of pre-pandemic social capital remained. Fostering social cohesion and reciprocity may increase resilience to mental disorders during a pandemic of infectious disease.

Occurrence and disease burden of respiratory syncytial virus and other respiratory pathogens in adults aged ≥65 years in community: A prospective cohort study in Japan.

BACKGROUND: The frequency and clinical profile of respiratory syncytial virus (RSV)-acute respiratory disease (ARD) in older adults in Japan has not been well-characterized. METHODS: This was a multicenter prospective observational cohort study to evaluate the occurrence rate of ARD in 1000 older adult participants (≥65 years) for 52 weeks during the 2019 to 2020 season. A multiplex polymerase chain reaction panel was used for pathogen detection in nasopharyngeal swab from participants diagnosed with ARD. Symptoms and impact of ARD was assessed using the Respiratory Infection Intensity and Impact Questionnaire (RiiQ™). The study was registered at UMIN (https://www.umin.ac.jp/ctr/): UMIN000037891. RESULTS: RSV-ARD was detected in 24/1000 (2.4%) participants and RSV-lower respiratory tract disease in 8/1000 (0.8%) participants. The median duration of RSV-ARD was 18 days. All 24 participants had utilized the medical services of outpatient visits and only 1 (4.2%) participant was hospitalized for RSV-ARD. The most common viruses other than RSV that caused ARD (detected in >10 participants) were human rhinovirus/enterovirus, parainfluenza 3, coronavirus OC43, human metapneumovirus, and influenza A/H1. The most frequent symptoms of RSV-ARD were cough, sore throat, nasal congestion, and expectoration. CONCLUSIONS: RSV was reported as a major pathogen for respiratory infections in older adults in Japan.

Standard Error of the Mean and Minimal Detectable Change of Gait Speed in Older Adults Using Japanese Long-Term Care Insurance System.

Evaluation of motor function, such as gait ability, can accurately predict the subsequent occurrence of disability in older adults. There are no reports of standard error of the mean (SEM) or minimal detectable change (MDC) with respect to gait in Japanese long-term care insurance-certified individuals. The purpose of this study was to investigate the values of preferred gait, fast gait, and the timed up and go (TUG) test. This study included 46 participants using the Japanese long-term care insurance system. (age 86.5 ± 6.6 years, 12 men, 34 women). The duration of three gait were measured twice using a stopwatch. The SEM was 0.07 for preferred gait, 0.09 for fast gait and 2.59 for TUG. The MDC was 0.19 for preferred gait, 0.26 for fast gait, and 7.17 for TUG. The SEM and MDC values of preferred gait, fast gait, and TUG in this study corroborated with those of previous studies, whereas others were different. Considering that gait speed differs with the country, it may be difficult to compare it among different population groups. We obtained the results of gait speed of Japanese long-term care insurance-certified individuals, which is a new finding.

Are Japanese Older Adults Rejuvenating? Changes in Health-Related Measures Among Older Community Dwellers in the Last Decade.

During the last three decades, Japan has become one of the world's top countries for longevity, and the increase in average life expectancy is accompanied by a sharp rise in older population 65 years of age and above to ∼28%. This study aimed to examine the changes in major health-related measures, including a physical constitution, physical function, and functional capacity of community-dwelling Japanese older people in the last decade. From the data of 13 longitudinal cohort studies on aging conducted in Japan with a total of 13,441 older subjects, this study analyzed the changes in six indices that are related to health and functioning of the older people; height, weight, body mass index, walking speed, grip strength, and instrumental activity of daily living, between 2007 (±2 years) and 2017 (±2 years). Comparison of data for the two periods between subjects matched for age group and gender evidently showed better health status and a slower decline in most of the health-related measures in 2017 compared to a decade ago. The results of this study indicate that the phenomenon of "rejuvenation" is occurring among the new generation of Japanese older adults, and the importance of this older population as a social resource in the super-aged society should be reacknowledged.

Factors Associated With Discussions Regarding Place of Death Preferences Among Older Japanese: A JAGES Cross-Sectional Study.

In Japan, many adults prefer to die at home; however, few have their preferences actually come true. While discussions regarding place of death preferences (DPDPs) are important for older adults, they are poorly documented. Therefore, we investigated the factors associated with older Japanese men and women having DPDPs. We used cross-sectional survey data collected for the Japan Gerontological Evaluation Study (JAGES). We applied multivariable logistic regression analysis to calculate the odds ratio (ORs) of having DPDPs separately between men (n = 2,770) and women (n = 3,038) aged ≥ 75 years. We considered 17 potential factors associated with having DPDPs, which were classified as either demographic, healthcare, family, or community factors. Among participants, 50.1% had DPDPs: 1,288 men (44.3%) and 1,619 women (55.7%). Older adults, DPDPs were associated with 5 additional factors; e.g. having a primary care physician (ORs = 1.47 [men] and 1.45 [women]), as were those who gave family and friends advice (ORs = 1.26 [men] and 1.62 [women]), and having people who listened to their concerns (ORs = 1.70 [men] and 1.81 [women]). Among men, DPDPs were associated with 3 additional factors; e.g. humorous conversations with their spouse (OR = 1.60). Among women, only one factor-reading newspapers (OR = 1.43) was associated with having DPDPs. Social networks with primary care physicians, family members, and friends may be important factors in promoting DPDPs. These gender-based differences in older adults relating to DPDPs should be considered when developing interventions to promote advance care planning that includes DPDPs.

Alcohol Energy Intake Is Related to Low Body Mass Index in Japanese Older Adults: Data from the 2010-2011 National Health and Nutrition Survey.

OBJECTIVE: The objective of this study was to identify lifestyle and nutritional factors associated with low BMI in Japanese older adults, with a focus on alcohol energy intake. DESIGN: Cross-sectional study. PARTICIPANTS: Data from 1,093 respondents (711 men and 382 women) to the National Health and Nutrition Survey aged 65 years and older were included in this study. MEASUREMENTS: Data were analyzed for associations between BMI and lifestyle, energy, and nutrient intake. Alcohol energy intake was calculated from total energy and participants were categorized into BMI quartiles. Energy-adjusted nutrient intakes were calculated as residuals from a regression model, with BMI as the independent variable and lifestyle factors and nutrient intake as dependent variables. Between-BMI quartile differences were assessed for each sex using multivariate logistic regression analysis. In addition, the nutrient intakes of men consuming more than 280 kcal and less than 280 kcal of alcohol energy per day were compared. RESULTS: Men and women in the lowest BMI quartile had lower total energy intake but higher alcohol energy intake than men in the other BMI quartiles. In multivariate logistic regression analysis, the lowest BMI quartile was associated with total energy (OR: 0.81, p = 0.0310) and alcohol energy intake (OR: 1.22, p = 0.0472) in men. In men, protein, carbohydrate, fat, calcium, iron, and vitamin intakes were less in those that consumed ≥ 280 kcal than in those that consumed < 280 kcal of alcohol per day. CONCLUSION: Our results demonstrate an association between alcohol energy intake and low BMI in older Japanese individuals.