Frailty trajectory among community-dwelling middle-aged and older adults in Korea: evidence from the Korean Longitudinal Study of Aging.

BACKGROUND: There is no study on the frailty trajectory including both middle-aged and older people, and the understanding of the long-term frailty trajectory is insufficient. This study aimed to identify the frailty trajectory, subgroups of the frailty trajectory, and the predictors that differentiate these subgroups among community-dwelling middle-aged and older adults. METHODS: The participants were 9,775 individuals aged 45 years and older who participated in the Korean Longitudinal Study of Aging (2006-2018). Frailty was measured using a frailty instrument comprising three items: grip strength weakness, exhaustion, and social isolation. Latent growth curve modeling and latent class growth modeling were performed to identify the frailty trajectory and latent classes of the trajectory. Multinomial logistic regression was used to confirm the predictors that classified the latent classes. RESULTS: Over 12 years, the slope of the frailty trajectory among the participants showed a gradual increase. In addition, there was a difference in the latent class of frailty trajectories among middle-aged and older adults. The middle-aged participants were divided into two groups: maintaining robustness and changing from pre-frailty to robustness. The older adults were divided into three groups: maintaining robustness, maintaining pre-frailty, and changing from the frailty to pre-frailty group. Regular exercise, cognitive dysfunction, and social participation were significant predictors that differentiated each latent class in both middle-aged and older adults; additionally, current smoking and the number of chronic diseases were significant predictors in middle-aged people. CONCLUSIONS: Various subgroups within the frailty trajectory existed among community-dwelling middle-aged and older adults. To reduce frailty, it is necessary to intervene with modifiable factors appropriate for each age group.

Investigating knowledge structure and research trends in child and adolescent health literacy research through network text analysis.

PURPOSE: This study aims to investigate the knowledge structure and research trends in child and adolescent health literacy research over the past 30 years by using network text analysis. METHOD: The study was conducted in four steps: 1) collecting abstracts, 2) keyword extraction and preprocessing, 3) creation of co-occurrence matrix, and 4) text network analysis. RESULTS: As a result of the centrality analysis, the upper-ranked core keywords were "health care," "health behavior," "prevention," "treatment," and "health promotion." In contrast to earlier times, "barrier," "caregiver," "school setting," and "QOL" have recently emerged as core keywords. CONCLUSIONS: Over the past 30 years, child and adolescent health literacy has been importantly addressed in both clinical and public health approaches. The results of the current study provide references for future research in child and adolescent health literacy. IMPLICATION FOR PRACTICE AND RESEARCH: This study suggests the need for additional research on school-based practices that can improve health literacy and for identifying validated and reliable multidimensional health literacy assessment instruments.

Impact of English Proficiency on Health Literacy in Older Korean Immigrants: Mediating Effects of Social Support and Acculturation.

Limited English proficiency (LEP) is one of the most influencing factors of personal health literacy (PHL) in the older immigrant population. Over the years, the proportion of older Korean immigrants with LEP has not improved and it is still noted as a major barrier to PHL. Therefore, organizational approaches are needed to enhance the PHL of older immigrants with LEP. This study aims to find the mediating effect of social support and acculturation between LEP and PHL by conceptualizing social support and acculturation as an organizational health literacy strategy. Data from 244 older Korean immigrants living in the states of Alabama and Georgia, USA, were used to conduct the study. Korean version of the Multidimensional Scale of Perceived Social Support (MSPSS), East Asian Acculturation Measure (EAAM), and Health Literacy Survey-12 Questionnaires (HLS-Q12) were used to measure the variables. The path analysis was conducted to find the serial mediation effects of social support and acculturation. The results showed that 77.5% of the participants reported not having fluent English proficiency. English proficiency (ß =- 0.21, p = 0.007), social support (ß = 0.17, p = 0.004), and acculturation (ß = 0.18, p = 0.011) significantly predicted the PHL, and social support (ß = 0.04, p = 0.028) and acculturation (ß = 0.14, p < 0.001) mediated the relationship between LEP and PHL. Discussion: Health-related organizations and communities are encouraged to provide external social support and acculturation opportunities to enhance PHL in older Korean immigrants with LEP.

Multilevel Factors Associated with Frailty among the Rural Elderly in Korea Based on the Ecological Model.

Frailty is prevalent in the rural elderly and, as a result, they are vulnerable to serious health problems. The purpose of this study was to examine the multilevel factors affecting frailty among the rural elderly using the ecological model. A total of 386 participants aged 65 years or older from 60 rural areas were included in the study. Frailty was measured using the Cardiovascular Health Study frailty index. Multilevel logistic regression analysis was used to identify the factors affecting frailty among the rural elderly. The results show that the levels of prevalence for robust, pre-frailty, and frailty groups were 81 (21%), 216 (56%), and 89 (23%), respectively. As for intrapersonal factors, old age, lower than middle school education, low and moderate levels of physical activity, depressive symptoms, and cognitive dysfunction significantly increased the risk of frailty; however, no interpersonal and community factors were significant in affecting frailty. The findings indicate that individualized strategies to encourage physical activity, prevent depressive symptoms, and preserve cognitive function are needed to prevent frailty in the rural elderly.

Social factors predicting improvement of frailty in community-dwelling older adults: Korean Frailty and Aging Cohort Study.

AIM: The study aimed to identify social factors predicting improvement of frailty in community-dwelling older adults after 2 years using a population-based cohort study. METHODS: We analyzed data from the 2016 and 2018 Korean Frailty and Aging Cohort Study. The participants of this study were 1428 community-dwelling older adults aged 70-84 years who were recruited from 10 medical centers across different regions. Frailty was measured using the five-item FRAIL scale, which evaluates fatigue, resistance, ambulation, illness and weight loss. Multilevel logistic regression analysis was used to examine baseline social factors that predict frailty improvement after 2 years by frailty status. RESULTS: In frail older adults, higher participation in social activities (odds ratio [OR] 1.17, 95% confidence interval [CI] 1.02-1.34) was significantly associated with frailty improvement. In pre-frail older adults, there were no significant social factors predicting the improvement of frailty status; however, other modifiable factors such as high and moderate levels of physical activity (OR 1.17, 95% CI 1.07-1.28, OR 1.13, 95% CI 1.03-1.25, respectively) and low depressive symptoms (OR 0.88, 95% CI 0.84-0.91) were associated with pre-frail improvements. High levels of physical activity (OR 1.16, 95% CI 1.02-1.33) were also associated with improvements of frailty. CONCLUSIONS: Different strategies depending on the level of frailty are necessary to improve frailty status. Timely and appropriate interventions can promote frailty improvement and prevent negative health outcomes in community-dwelling older adults. Geriatr Gerontol Int 2021; 21: 465-471.

The Cross-Lagged Panel Analysis between Frailty and Physical Activity among Community-Dwelling Older Adults by Age Groups.

Objectives: This study was to investigate the reciprocal relationship between frailty and physical activity among older adults by age group (middle-old: 70-79 years; oldest-old: 80-84 years) within 2 years using cross-lagged panel analysis. Methods: The study data were derived from the Korean Frailty and Aging Cohort Study, and a total of 1092 participants were included. Results: Frailty and high physical activity had significant reciprocal relationships in the middle-old group, which indicates that frailty was associated with less high physical activity, and high physical activity predicts less frailty after 2 years. In the oldest-old group, there was no statistically significant reciprocal relationship between frailty and any level of physical activity reference to low physical activity and vice versa after 2 years. Discussion: Further studies on the relationship between frailty and physical activity of the oldest-old population and specific physical activity guidelines for older adults are needed.

Factors affecting reversion from mild cognitive impairment to normal cognition in midlife to later life in Korea: A national population study.

AIM: The purpose of this study was to identify the midlife and later life factors affecting reversion from mild cognitive impairment to normal cognition after 4 years. METHODS: We analyzed data from the 2012 and 2016 Korean Longitudinal Study of Aging. The participants of this study were Korean community-dwelling adults aged ≥45 years who showed mild cognitive impairment in 2012. They were divided into midlife (<65 years) and later life (≥65 years) based on their age in 2012. Cognitive function was assessed by the Korean Mini-Mental State Examination in 2016. Multiple logistic regression analysis was carried out to determine the factors affecting reversion by age group. RESULTS: Among participants with mild cognitive impairment, 52.0% in midlife and 26.6% in later life reverted to normal cognition after 4 years. In midlife, higher education (OR 1.97, 95% CI 1.15-3.36), fewer chronic diseases (OR 0.78, 95% CI 0.61-0.99), lower levels of depressive symptoms (OR 0.95, 95% CI 0.90-0.99) and higher participation in social activities (OR 1.91, 95% CI 1.27-2.87) were significantly associated with reversion. In later life, higher baseline cognitive function (OR 1.30, 95% CI 1.14-1.47) and higher participation in social activities (OR 1.35, 95% CI 1.02-1.79) were significantly associated with reversion. CONCLUSIONS: The reversion rate in midlife was higher than that of later life. More modifiable factors affecting reversion were found in midlife, suggesting that assessment and intervention at an early age should be considered. Geriatr Gerontol Int 2019; 19: 1129-1135.

Ischemic brain injury decreases dynamin-like protein 1 expression in a middle cerebral artery occlusion animal model and glutamate-exposed HT22 cells.

Dynamin-like protein I (DLP-1) is an important mitochondrial fission and fusion protein that is associated with apoptotic cell death in neurodegenerative diseases. In this study, we investigated DLP-1 expression in a focal cerebral ischemia animal model and glutamate-exposed hippocampal-derived cell line. Middle cerebral artery occlusion (MCAO) was surgically induced in adult male rats to induce focal cerebral ischemic injury. Brain tissues were collected 24 hours after the onset of MCAO. MCAO induces an increase in infarct volume and histopathological changes in the cerebral cortex. We identified a decrease in DLP-1 in the cerebral cortices of MCAO-injured animals using a proteomic approach and Western blot analysis. Moreover, glutamate treatment significantly decreased DLP-1 expression in a hippocampal-derived cell line. The decrease in DLP-1 indicates mitochondrial dysfunction. Thus, these results suggest that neuronal cell injury induces a decrease in DLP-1 levels and consequently leads to neuronal cell death.

Soluble Neuregulin-1 from Microglia Enhances Amyloid Beta-induced Neuronal Death.

Neuregulin-1 (NRG-1) is a ligand of the epidermal growth factor receptor (erbB), and its interaction involves activation of the glutamatergic N-methyl-Daspartate receptor, which increases the expression of the ß2 subunit of the γ- aminobutyric acid receptor and subunits of the nicotinic acetylcholine receptor. In the dentate gyrus of 14-month-old Tg2576 mice, NRG-1 was strongly expressed compared with age-matched controls. The supernatant of oligomeric amyloid ß peptide (Aß42)-treated glial cells enhanced the Aß42;-induced cytotoxic effects, but the expression of Fas ligand and tumor necrosis factor-related apoptosis-inducing ligand in microglial cells was not changed upon cytotoxic treatment. This suggests that the oligomeric form of Aß42 toxicity is not related to apoptosis, which is mediated by cell-to-cell interaction. During the 24-h incubation, the secretion of the soluble form of NRG-1 was increased, but interleukin 6 secretion was not changed. Further, soluble NRG-1 increased Aß42-induced toxicity. In conclusion, soluble NRG-1 significantly enhanced oligomeric Aß42-induced toxicity through the activation of endoplasmic reticulum stress by the increase of a phospho-translation initiation factor 2 alpha (p-eIF2α).

The early synthesis of p35 and activation of CDK5 in LPS-stimulated macrophages suppresses interleukin-10 production.

Interleukin-10 (IL-10) is an important anti-inflammatory cytokine that is produced primarily by macrophages. We investigated mechanisms by which the timing of IL-10 production was controlled in macrophages and found that cyclin-dependent kinase 5 (CDK5) activity was markedly increased in lipopolysaccharide (LPS)-stimulated macrophages through the synthesis of the CDK5-binding partner and activator p35. Degradation of p35 released the inhibition on anti-inflammatory signaling mediated by CDK5-p35 complexes. The transiently active CDK5-p35 complexes limited the LPS-stimulated phosphorylation and activation of various mitogen-activated protein kinases (MAPKs), thereby preventing the premature production of SOCS3 (suppressor of cytokine signaling 3), an inhibitor of inflammatory responses in macrophages, and IL-10. Furthermore, we showed that dextran sodium sulfate failed to induce colitis in p35-deficient mice, which was associated with the enhanced production of IL-10 by macrophages. Together, our results suggest that CDK5 enhances the inflammatory function of macrophages by inhibiting the MAPK-dependent production of IL-10.