The Mexican Cognitive Aging Ancillary Study (Mex-Cog): Study Design and Methods

ObjectiveDescribe the protocol sample and instruments of the Cognitive Aging Ancillary Study in Mexico (Mex-Cog). The study performs an in-depth cognitive assessment in a subsample of older adults of the ongoing Mexican Health and Aging Study (MHAS). The Mex-Cog is part of the Harmonized Cognitive Assessment Protocol (HCAP) design to facilitate cross-national comparisons of the prevalence and trends of dementia in aging populations around the world, funded by the National Institute on Aging (NIA).MethodsThe study protocol consists of a cognitive assessment instrument for the target subject and an informant questionnaire. All cognitive measures were selected and adapted by a team of experts from different ongoing studies following criteria to warrant reliable and comparable cognitive instruments. The informant questionnaire is from the 10/66 Dementia Study in Mexico.ResultsA total of 2,265 subjects aged 55-104 years participated, representing a 70% response rate. Validity analyses showed the adequacy of the content validity, proper quality-control procedures that sustained data integrity, high reliability, and internal structure.ConclusionsThe Mex-Cog study provides in-depth cognitive data that enhances the study of cognitive aging in two ways. First, linking to MHAS longitudinal data on cognition, health, genetics, biomarkers, economic resources, health care, family arrangements, and psychosocial factors expands the scope of information on cognitive impairment and dementia among Mexican adults. Second, harmonization with other similar studies around the globe promotes cross-national studies on cognition with comparable data. Mex-Cog data is publicly available at no cost to researchers.     

Healthy but unhappy? Cross-national comparative analysis of depressive symptoms in Japanese vs. Korean elders

BackgroundJapan and South Korea, two neighbouring countries in East Asia, enjoy the highest life expectancies in the world, yet suffer paradoxically from high suicide rates.AimWe sought to conduct a cross-national comparative analysis of depressive symptoms among older adults in Japan vs. Korea, focusing particularly on poverty and physical health status.MethodsWe used nationally representative samples aged 65 and over from the Comprehensive Survey of Living Conditions in Japan and the Korean Community Health Survey in South Korea. Multivariate logistic regression models were conducted to examine if equivalized household income, poor self-rated health, disability and comorbidity (number of diseases) were associated with depressive symptoms, adjusting for age, education, marital status, alcohol use, smoking and living alone.ResultsOlder Japanese adults with poor self-rated health and disability were more likely to report depressive symptoms, but income level was not significantly associated with mental distress. By contrast, among older Korean people, depressive symptoms were strongly patterned by household income level, as well as poor self-rated health, disability, and comorbidity.ConclusionPoor physical health status was correlated with depressive symptoms among both Japanese and Korean seniors. However, income level was associated with depressive symptoms among only Korean elders, but not Japanese. Thus, the current generation of older Japanese adults appears to enjoy (relative) financial security, longevity, and mental wellbeing. By contrast, older Koreans experience high levels of mental distress, especially if they are financially insecure.     

Estimating quality of life with biomarkers among older Korean adults: A machine-learning approach

BackgroundWhile health-related quality of life (HRQoL) has clinical value, its determinants, particularly objective health-related measurements, have not been fully explored. This study seeks to identify the biological indicators that relate to HRQoL among a group of older Korean adults using a machine-learning approach.MethodsWe used physical and mental scores from the 36-item Short Form Health Survey (SF-36) to measure HRQoL among older Korean adults who participated in the Korean Longitudinal Study of Aging (KLoSA) biomarker pilot study (N = 385). The variables for the multivariate penalized regression analysis included demographic factors, medical measurements, physical performance, and health-related behaviors.ResultsThe multivariate profiles identified several significant biomarkers that relate to quality of life. Among the 20 variables, handgrip strength was the most powerful indicator in both men and women for the SF-36 physical scores, followed by walking speed. Age and total sleep duration exclusively were significantly associated with the SF-36 physical scores only in women, whereas body mass index, blood pressure, and sit-to-stand times were unique elements in men.ConclusionsThe present study suggests significant physical indicators that explain quality of life in elderly populations, using a data-driven approach. Based on these findings, maintaining a good level of physical performance is considered a key element of successful aging.     

The neighborhood effect of cognitive function on self-rated health: A population-based observational study

This study investigates the interaction between the neighborhood effect of cognitive function on self-rated health among middle aged and older adults. Data from the Korean Longitudinal Study on Aging (KLoSA) were analyzed. A total of 9,998 participants were selected for biennial follow-ups from 2006 to 2018 to estimate the probability of change in cognitive function according to individual, regional and dependent variables. A generalized estimating equation (GEE) model and chi-square test were used. The odds ratio (OR) of underestimation, when an individual's cognitive function is lower than his/her regional average of cognitive function, was 1.173 times higher (95 % Confidence Interval [CI]: 1.108–1.241, p-value: <.0001) compared to accurate, when an individual's cognitive function is equal to his/her regional average of cognitive function. The OR of individuals with low cognitive function in regions with low cognitive function levels had the highest probability of poor SRH (self-rated health) (OR: 3.525; 95 % CI: 3.182–3.905, p-value: <.0001) compared to individuals with high cognitive function in regions with high cognitive function levels. Findings speak of the importance of the neighborhood effect of cognitive function on self-rated health among Korean middle aged and older adults. Further research is needed to investigate the potential mediation of pleasurable mechanisms in the rapidly aging population of Korea.     

Healthy aging predicts mortality risks: Results from the Korean longitudinal study of aging (2006–2014)

IntroductionWhile there has been some gerontological research on healthy aging, few studies have identified a reasonable health status for the older adults. Guided by the four healthy aging concepts in studies from the US and Spain, this study sought to determine a useful definition for Korean older adults by examining the associations between each of the four healthy aging definitions and mortality.MethodsA longitudinal analysis was conducted based on the 2,960 older people (65 years or older) who participated in the Korean Longitudinal Study of Aging (2006–2014). Four healthy aging gradient definitions (Rowe and Kahn, Group Ⅰ, Group II, and Group III) were determined: absence of disease, free of disability, physical and cognitive function, and engagement with life.ResultsThe young old who failed to achieve healthy aging were found to have a higher risk of mortality in all four healthy aging gradient definitions in both males (HR range from 4.15 to 5.39) and females (HR range from 4.07 to 9.55). In old old, however, the unhealthy aging mortality risk in Rowe and Kahn's definition was disappeared, but predominant mortality risks were found in Group III for both male (HR = 3.16, 95% CI 1.67 – 5.98) and female (HR = 3.65, 95% CI 1.36 – 9.81)ConclusionTo promote healthy aging, we suggest that the definition for the young old includes rigid disease criteria, and old old emphasize functional ability. Age-specific aims for healthy aging may be useful for defining healthy aging.     

Gender differences in predictors of mental health among older adults in South Korea

As aging is occurring at a rate never before seen in South Korea, the present study examines the predictors of mental health in a nationally representative sample of older adults (n = 4,155), drawn from Wave I of the Korean Longitudinal Study on Aging. Findings show that sociodemographic factors, chronic health conditions, level of cognition, and social activities contribute to life satisfaction and mental health among older adults in South Korea. Life satisfaction is mainly determined by sociodemographic factors for both women and men. Compared to women, men's levels of depression and life satisfaction appear to be more influenced by their health, cognitive functioning, and social activity participation. Implications for practice and policy are discussed.     

Role of Physical Activity in Reducing Cognitive Decline in Older Mexican‐American Adults

The effect of physical activity on cognitive function in older adults from minority and disadvantaged populations is not well understood. This study examined the longitudinal association between physical activity and cognition in older Mexican Americans. The study methodology included a prospective cohort with longitudinal analysis of data from the Hispanic Established Populations for the Epidemiologic Study of the Elderly. General linear mixed models were used to assess the associations and interactions between physical activity and cognitive function over 14 years. Community‐based assessments were performed in participants' homes. Physical activity was recorded for 1,669 older Mexican Americans using the Physical Activity Scale for the Elderly. Cognition was measured using the Mini‐Mental State Examination (MMSE) and separated into memory and nonmemory components. A statistically significant positive association was observed between levels of physical activity and cognitive function after adjusting for age, sex, marital status, education, and comorbid health conditions. There was a statistically significant difference in MMSE scores over time between participants in the third (β = 0.11, standard error (SE) = 0.05) and fourth (β = 0.10, SE = 0.2) quartiles of physical activity and those in the first. The protective effect of physical activity on cognitive decline was evident for the memory component of the MMSE but not the nonmemory component after adjusting for covariates. Greater physical activity at baseline was associated with less cognitive decline over 14 years in older Mexican Americans. The reduction in cognitive decline appeared to be related to the memory components of cognitive function.     

Association between self-reported physical activity and indicators of cardiovascular risk in community-dwelling older adults with hypertension in Korea: A cohort study

The prevalence of hypertension has increased with the rise in the elderly population, and high blood pressure is a major cause of cardiovascular disease. Physical activity is an important strategy for preventing cardiovascular disease. The study aimed to explore the association between physical activity and cardiovascular risk indicators in community-dwelling older adults with hypertension.This study is a secondary data analysis of a prospective longitudinal study using data from the Elderly Cohort Database of the National Health Insurance Service in South Korea between 2002 and 2013. Participants included 10,588 older adults (≥60 years) with hypertension. Data assessing self-reported physical activity and directly measured blood pressure, fasting blood glucose, body mass index, and total cholesterol levels throughout the 12-year study were extracted from the original database and analyzed. Participants were categorized into 4 groups based on the reported changes in physical activity over time: Group I (Maintaining No Physical Activity Group), II (Changing from No Physical Activity to Physical Activity Group), III (Changing from Physical Activity to No Physical Activity Group), and IV (Maintaining Physical Activity Group). Cox proportional hazard model was used to confirm the risk of cardiovascular indicators over time in each group.Participants’ mean age was 64.2 years in the initial year of 2002. The number of participants in Groups I, II, III, and IV was 4032, 2697, 1919, and 1940, respectively. Group IV showed a significant decline in risk for uncontrolled hypertension compared to Group I (hazard ratio = 0.87, 95% confidence interval [0.800–0.948]). Group II showed a significant decrease in risk for uncontrolled diabetes compared to Group I (hazard ratio = 0.94, 95% confidence interval [0.888–0.999]).The findings indicated that physical activity is a significant factor associated with indicators of cardiovascular risk in older people with high blood pressure. Healthcare providers should be aware of the importance of older adults’ physical activity and encourage them to perform and maintain it steadily for better long-term cardio-metabolic outcomes.     

Physical Activity and Depressive Symptoms Interact to Predict Executive Functioning Among Community-Dwelling Older Adults

Background/Study Context: Physical activity is beneficial for the executive functioning (EF) of older adults, but may be particularly protective of EF when they are cognitively vulnerable, such as during depressive episodes. Intervention studies support more potent effects of physical activity on EF among clinically depressed older adults, although these results may have limited generalizability to the daily mood and physical activity of healthy, community-dwelling older adults.

Methods: The current study aimed to test whether physical activity among older adults was more protective of EF during periods of cognitive vulnerability due to mildly elevated depressive symptoms. Longitudinal data from 150 generally healthy, community-dwelling older adults were collected semiannually and analyzed with multilevel modeling.

Results: Physical activity was more protective of EF within individuals during periods of relatively elevated depressive symptoms.

Conclusions: The power of physical activity to protect EF during periods of cognitive vulnerability may extend to community-dwelling older adults with nonclinical levels of depressive symptoms.     

Cognitive functions and physical activity in aging when energy is lacking

Declines in subjective energy availability and cognitive functions could explain the decrease in physical activity observed across aging. However, how these factors interact remains unknown. Based on the theory of effort minimization in physical activity (TEMPA), we hypothesized that cognitive functions may help older adults to maintain physical activity even when energy availability is perceived as insufficient. This study used data of 104,590 adults from 21 European countries, from the Survey of Health, Ageing and Retirement in Europe (SHARE), including 7 measurement occasions between 2004 and 2017. Cognitive functions were assessed with verbal fluency and delayed recall, using the verbal fluency test and the 10-word delayed recall test. Physical activity and subjective energy availability were self-reported. Results of linear mixed-effects models revealed that cognitive functions moderated the associations between subjective energy availability and physical activity. Moreover, as adults get older, cognitive functions became critical to engage in physical activity regardless the availability of perceived energy. Sensitivity and robustness analyses were consistent with the main results. These results suggest that cognitive functions may help older adults to maintain regular physical activity even when energy for goal pursuit becomes insufficient, but that the protective role of cognitive functions becomes critical at older age, irrespective of the state of perceived energy.

     

Physical activity in community-dwelling older people: a review of systematic reviews of interventions and context

BackgroundResearch evidence on the importance of physical activity for prevention and delay of long-term conditions is strong. However, activity rates decline substantially over the life course, particularly around later life. This review is part of a comprehensive evidence synthesis of preventive interventions in older age, with a focus on healthy behaviours to identify evidence gaps and inform policy relating to ageing well and cognitive health. An overview of systematic reviews of physical activity was conducted to explore in adults aged 55 years and older: (review 1) the effectiveness of physical activity for primary prevention of cognitive decline and dementia; (review 2) interventions effective for increasing physical activity uptake and maintenance; and (review 3) barriers and facilitators to physical activity.MethodsMultiple databases were searched for studies in English from Organisation for Economic Co-operation and Development countries between 2000 and 2014 (Medline, Embase, PsycINFO, CINAHL, Social Science Index, the Cochrane Collaboration and Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Health Technology Assessment, and York CRD Database). Search strategy covered the following domains and concepts: ageing and older people; health behaviours and risk reduction relating to diet, physical activity, inactivity, alcohol, smoking; and risk reduction relating to loneliness and isolation, sun exposure, hearing, and vision. The quality of reviews 1 and 2 were assessed with AMSTAR.Findings35 systematic reviews were included. In review 1 (12 systematic reviews, 7751 participants), physical activity conferred mild, positive effects on cognition in older adults with and without previous cognitive impairment. However, evidence of a dose–response association was insufficient, and evidence on the effects of physical activity on delay of cognitive decline and dementia onset was inconclusive. The evidence in review 2 (16, 75 194) supported the effectiveness of various interventions, including group-delivered, centre-based, and cognitive approaches on short-term uptake of physical activity behaviour. In review 3 (7, 15 921), barriers included health status, previous physical activity habits and experiences, and cultural sensitivity, whereas facilitators included enjoyable activities and convenient scheduling.InterpretationPhysical activity can offer small benefits to brain health, but evidence on how much activity is required to produce this effect is lacking. Interventions aimed at increasing physical activity in older people should be encouraged while considering barriers and facilitators to behaviour change. In the absence of evidence on the minimum physical activity effective for maintaining brain health and increasing participation, public health messages should be aimed at promoting acceptable levels of physical activity above normal daily activities in older people. To maintain long-term participation in physical activity, individualised interventions modelled using behavioural theories may be required.FundingNational Institute for Health Research (NIHR) School for Public Health Research Ageing Well Programme and the NIHR Collaborations for Leadership in Applied Health Research and Care East of England.     

Factors influencing attitudes toward advance directives in Korean older adults

AimWe aimed to determine the factors influencing attitudes toward advance directives in Korean older adults with consideration of an Asian cultural background.MethodsWe recruited community-dwelling older adults aged 60 years or older at a regional senior welfare center in Korea. Demographic factors and mental and physical health status were examined using questionnaires and a physical examination. The questionnaire also assessed perceived necessity of advance directives and related experiences.ResultsMost participants (79.32%) agreed that advance directives were necessary. Older adults with high education levels (odds ratio [OR] 2.31, 95% confidence interval [CI] 0.84–6.34), low economic status (OR 2.09, 95% C.I. 0.60–7.27), and poor cognitive function (adjusted odds ratio [aOR] 2.10, 95% CI 0.89–4.97) had a greater odds of agreeing that advance directives are necessary. All participants with self-care problems (9/9) and most participants with at risk status of physical functioning (13/14) reported agreement. Death-related experiences were also associated. Notably, individuals who had discussions on end-of-life care with family members showed a greater odds of agreeing that advance directives are necessary (aOR 2.12, 95% CI 0.88–5.11).ConclusionsThe factors associated with increased agreement that advance directives are necessary were high education level, low economic status, poor cognitive function, problems in self-care, poor physical functioning, death-related experiences. Especially, discussions of end-of-life care with family members increased the agreement. Thus, discussion on end-of-life care should be encouraged and the factors influencing older adults’ attitudes toward advance directives should be considered in developing policies for such discussion.     

Association between Fear of Falling (FOF) and all-cause mortality

ObjectiveTo longitudinally investigate the effect of fear of falling on all-cause mortality.MethodsData from the KLoSA from 2006 to 2016 was used and 10,219 middle aged and older adults were included for analysis. The association between fear of falling and all-cause mortality was analyzed by Cox proportional hazard model with controlling for demographic characteristics, number of chronic conditions, depressive symptoms and fall experience.ResultsOf the 10,219 individuals at baseline 2006, those with fall experience for 2 years were 411 participants (4.2 %) and about 18.5 % of these participants (n: 76) died. In terms of FOF, 14.83 % of participants (1,515/10,219) reported serious fear for falling. Adjusted hazard ratio (HR) of all-cause mortality shows those who are very afraid of falling had a significantly increased risk of mortality compared with those without a FOF (HR 1.861, 95 % CI 1.589–2.179, P-value:.0001).ConclusionThis study shows a statistically significant association between fear of falling and all-cause mortality in a Korean middle aged and aged population.     

Association between executive function and physical performance in older Korean adults: findings from the Korean Longitudinal Study on Health and Aging (KLoSHA)

Reduced executive function and physical performance are common age-related conditions. This study evaluated the associations between executive function and physical performance in a representative sample of older adults. Cross-sectional data were analyzed from a population-based sample of 629 men and women aged 65 or older and living in one typical city in Korea. Specific aspects of executive function were assessed using the trail making test, digit span test, and lexical fluency test to measure set shifting, working memory and cognitive flexibility functions. Physical performance was measured using performance-oriented mobility assessment (POMA) scores and isokinetic muscle strength. Subjects’ self-efficacy was also assessed using the activities-specific balance confidence (ABC) scale. Results of the lexical fluency test were associated with POMA scores and muscle strength, independent of age, gender, education, comorbidity, physical activity status, depression, and global cognition, suggesting that reduced cognitive flexibility is associated with reduced physical performance and muscle strength. Self-efficacy was also independently associated with physical performance and muscle strength. Clinicians need to consider the association between executive function and physical performance when working to improve physical functioning in an aged population.     

Changes in physical activity and cognitive decline in older adults living in the community

Accumulating evidence suggests that physical activity may be beneficial in preserving cognition in late life. This study examined the association between baseline and changes in physical activity and cognitive decline in community-dwelling older people. Data were from the Korean Longitudinal Study of Aging, with 2605 aged 65 years and older subjects interviewed in 2006 and followed up for 2 years. Cognitive decline was defined by calculating the Reliable Change Index using the Mini-Mental State Examination. Physical activity levels were categorized as sedentary, low, or high. Changes in physical activity were classified as inactive, decreaser, increaser, or active. Logistic regression analysis of baseline and changes in physical activity with cognitive decline was performed. Compared with the sedentary group at baseline, both the low and high activity groups were less likely to experience cognitive decline. The active (odds ratio [OR] = 0.40, 95 % confidence interval [CI] 0.23–0.68) and increaser (OR = 0.45, 95 % CI 0.27–0.74) group, compared with the inactive counterpart, demonstrated a significantly lower likelihood of cognitive decline. Older adults who remained active or increased activity over time had a reduced risk of cognitive decline. Engagement in physical activity in late life may have cognitive health benefits.     

Effect of depressive disorder on cognitive decline

This study longitudinally investigates the effect of depressive disorder on psychiatric disorder in middle aged and aged population from the Korean Longitudinal Study of Aging. Data from the Korean Longitudinal Study of Aging (KLoSA) from 2006 to 2016 was assessed using longitudinal data analysis and 7515 research samples were included after excluding those with cognitive decline and missing information at baseline (2006). To analyze the association between depressive disorder on cognitive decline in middle aged and aged population, generalized estimating equation (GEE) model and chi-square test were used. The association between depressive symptom during a week and center for epidemiological studies depression (CESD) on cognitive decline was statistically significant, respectively with the following Odds ratio (OR) predicting decreased MMSE score: OR = 0.89 (p < .0001) for 5–7 days vs. less than a day and B = 0.91 (p < .0001) for depression (8–10) vs. healthy (zero). In terms of cognitive decline, depressive symptom was higher for 5–7 days (OR = 3.79, p < .0001) compared to less than a day. This study shows a statistically significant association between depressive disorder and cognitive decline in a Korean middle aged and aged population. These findings suggest the importance of managing depressive disorder for incident cognitive decline.     

Relationships between cognitive function and frailty in older Korean adults: The moderating effect of the number of teeth

BackgroundCognitive function and physical frailty are known to be closely related. Among older adults with dementia, those who wear dentures have a higher mortality rate than those who do not wear them. This suggests the possibility that oral health may affect the cognitive-frailty relationship. This study aims to investigate whether the number of teeth present, acts as a moderating variable in the cognitive function-frailty relationship.MethodsData were obtained from the cross-sectional baseline study of the Korean Frailty Aging Cohort Study (2016–2017). Cognitive function was assessed using the Mini-Mental State Examination. Frailty score was based on the Cardiovascular Health Study Index. Oral condition was evaluated by the number of teeth present and analyzed using categories of 0-9 teeth, 10-19 teeth, and ≥20. The moderation effect was analyzed using the ordinary least squares (OLS) regression.ResultsData on 2,310 older adults (1,110 men; mean age 75.9 ± 3.9 years) was analyzed. Adjusting for age, sex, income, education, alcohol drinking, body mass index, and number of comorbidities, cognitive function and frailty showed a negative association (B=-.030, p = .011). In the 10-19 teeth category, compared to the 0-9 teeth category, a negative association with frailty was found (B=-.152, p = .026). A significant interaction effect between the number of teeth and cognitive function was detected (p = .007).ConclusionThe number of teeth may modify the degree of the association between cognitive function and frailty. For effective frailty management of older persons, cognitive function management and oral management should be considered and performed together.     

Childhood Poverty and Depressive Symptoms for Older Adults in Mexico: A Life-Course Analysis

This study applies life-course theories of latent (direct), pathway (indirect) and conditional effects in an analysis of childhood poverty on later-life depressive symptoms among older adults in Mexico. Data are from the 2001 Mexican Health and Aging Study (MHAS), a nationally representative sample of older adults born before 1951 (n?=?8696). Respondents had a mean of 3.6 past-week depressive symptoms and 71 % had no household sanitation facilities before age 10; this measure served as a proxy for childhood poverty. Childhood poverty is significantly related to scores on an adapted 9-item CES-D scale in the full model (b?=?0.27, p?<?0.001). This effect is partially mediated by four adult socio-economic status measures, although decomposition analysis reveals the mediation effect to be primarily driven by educational achievement. These findings have important implications for Mexico’s rapidly aging population as well as efforts for childhood poverty reduction and gains in education.     

Perceptions of Aging in Two Cultures: Korean and American Views on Old Age

The current study investigated whether beliefs about aging vary by culture, age, and gender. The Lasher and Faulkender (Int. J. Aging Hum. Dev., 37:247–259, 1993) Anxiety about Aging scale was administered to 153 American and 167 South Korean men and women divided into three age groups: young (18–39), middle-aged (40–59), and older (60–91) adults. Significant cultural differences were found for the total anxiety scale and three of the four subscales. Compared to Americans, Koreans portrayed higher overall levels of anxiety about aging, and greater fear of old people, psychological concerns, and concerns over physical appearance. For Koreans, younger adults had greater fear of old people, whereas among Americans, older adults had greater fear of old people. In both cultures, the older adults had greater psychological concerns and fear of losses than did the younger groups, and American women showed more anxiety about aging and concerns over physical appearance than their male counterparts. Results are discussed in relation to aging in different cultural contexts.