Sexual dimorphism of frailty and cognitive impairment: Potential underlying mechanisms (Review)

Understanding exogenous factors and biological mechanisms for cognitive frailty: A multidisciplinary scoping review

Cognitive frailty (CF) is the conjunction of cognitive impairment without dementia and physical frailty. While predictors of each element are well-researched, mechanisms of their co-occurrence have not been integrated, particularly in terms of relationships between social, psychological, and biological factors. This interdisciplinary scoping review set out to categorise a heterogenous multidisciplinary literature to identify potential pathways and mechanisms of CF, and research gaps. Studies were included if they used the definition of CF OR focused on conjunction of cognitive impairment and frailty (by any measure), AND excluded studies on specific disease populations, interventions, epidemiology or prediction of mortality. Searches used Web of Science, PubMed and Science Direct. Search terms included "cognitive frailty" OR (("cognitive decline" OR "cognitive impairment") AND (frail*)), with terms to elicit mechanisms, predictors, causes, pathways and risk factors. To ensure inclusion of animal and cell models, keywords such as "behavioural" or "cognitive decline" or "senescence", were added. 206 papers were included. Descriptive analysis provided high-level categorisation of determinants from social and environmental through psychological to biological. Patterns distinguishing CF from Alzheimer's disease were identified and social and psychological moderators and mediators of underlying biological and physiological changes and of trajectories of CF development were suggested as foci for further research.

Development and validation of machine learning models to predict frailty risk for elderly

AIMS

Early identification and intervention of the frailty of the elderly will help lighten the burden of social medical care and improve the quality of life of the elderly. Therefore, we used machine learning (ML) algorithm to develop models to predict frailty risk in the elderly.

DESIGN

A prospective cohort study.

METHODS

We collected data on 6997 elderly people from Chinese Longitudinal Healthy Longevity Study wave 6-7 surveys (2011-2012, 2014). After the baseline survey in 1998 (wave 1), the project conducted follow-up surveys (wave 2-8) in 2000-2018. The osteoporotic fractures index was used to assess frailty. Four ML algorithms (random forest [RF], support vector machine, XGBoost and logistic regression [LR]) were used to develop models to identify the risk factors of frailty and predict the risk of frailty. Different ML models were used for the prediction of frailty risk in the elderly and frailty risk was trained on a cohort of 4385 elderly people with frailty (split into a training cohort [75%] and internal validation cohort [25%]). The best-performing model for each study outcome was tested in an external validation cohort of 6997 elderly people with frailty pooled from the surveys (wave 6-7). Model performance was assessed by receiver operating curve and F2-score.

RESULTS

Among the four ML models, the F2-score values were similar (0.91 vs. 0.91 vs. 0.88 vs. 0.90), and the area under the curve (AUC) values of RF model was the highest (0.75), followed by LR model (0.74). In the final two models, the AUC values of RF and LR model were similar (0.77 vs. 0.76) and their accuracy was identical (87.4% vs. 87.4%).

CONCLUSION

Our study developed a preliminary prediction model based on two different ML approaches to help predict frailty risk in the elderly.

IMPACT

The presented models from this study can be used to inform healthcare providers to predict the frailty probability among older adults and maybe help guide the development of effective frailty risk management interventions.

IMPLICATIONS FOR THE PROFESSION AND/OR PATIENT CARE

Detecting frailty at an early stage and implementing timely targeted interventions may help to improve the allocation of health care resources and to reduce frailty-related burden. Identifying risk factors for frailty could be beneficial to provide tailored and personalized care intervention for older adults to more accurately prevent or improve their frail conditions so as to improve their quality of life.

REPORTING METHOD

The study has adhered to STROBE guidelines.

PATIENT OR PUBLIC CONTRIBUTION

No patient or public contribution.

Epigenetics of inflammation in hypothalamus pituitary gonadal and neuroendocrine disorders

The hormone producing hypothalamus, pituitary and gonadal are arranged in hierarchy to form the hypothalamic-pituitary-gonadal axis (HPG axis). The axis is neuroendocrine in nature and releases hormones in response to the inputs from nervous systems. The axis maintains homeostasis and ensures smooth body functions, particularly those related to growth and reproduction. A deregulated HPG axis, such as observed under inflammation and other conditions, is therefore associated with several disorders such as polycystic ovary syndrome, functional hypothalamic amenorrhea etc. Several factors, both genetic as well as environmental, in addition to aging, obesity etc. affect HPG axis with resulting effects on puberty, sexual maturation and reproductive health. More research is now indicative of a role of epigenetics in mediating these HPG-affecting factors. Hypothalamus-secreted gonadotropin-releasing hormone is important for eventual release of sex hormones and it is subjected to several neuronal and epigenetic regulations. Gene promoter methylation as well as histone methylations and acetylations form the backbone of epigenetic regulation of HPG-axis, as the incoming reports suggest. Epigenetic events also mediate several feedback mechanisms within HPG axis and between HPG axis and the central nervous system. In addition, data is emerging for a role of non-coding RNAs, particularly the miRNAs, in regulation and normal functioning of HPG axis. Thus, the epigenetic interactions need better understanding to understand the functioning and regulation of HPG axis.

Bidirectional relationship between frailty and cognitive function among Chinese older adults

BACKGROUND

Frailty and cognitive function are two common aging-related conditions among older adults. This study examined the bidirectional relationship between frailty and cognitive function according to sex.

METHODS

All older adults aged ≥65 years who participated in the 2008 and 2014 waves of the Chinese Longitudinal Healthy Longevity Survey were included in this study. Binary logistic regression and generalized estimating equation models were used to determine the bidirectional relationship between frailty and cognitive function in cross-sectional and cohort studies, and sex differences were assessed.

RESULTS

We included 12,708 participants who were interviewed in the baseline study. The participants' mean (standard deviation) age was 85.6 (11.1%) years. In the cross-sectional study, the multivariate-adjusted odds ratio (OR; 95% confidence interval [CI]) for pre-frailty and frailty among participants with cognitive impairment was 3.68 (3.29-4.13). Older adults with pre-frailty and frailty had higher risks of cognitive impairment (OR = 3.79, 95% CI: 3.38-4.25). The GEE models showed that pre-frailty and frailty predicted a higher likelihood of cognitive impairment (OR = 2.02, 95% CI, 1.67-2.46) during follow-up. Moreover, the temporal relationship between these relationships differed slightly by sex. Older women with cognitive impairment at baseline were more likely to develop pre-frailty or frailty than did older men.

CONCLUSIONS

This study demonstrated a significant bidirectional relationship between frailty and cognitive function. Moreover, this bidirectional relationship varied by sex. These findings confirm the need to integrate sex-specific interventions for frailty and cognitive functioning problems to improve the quality of life of older adults.

The impact of Otago exercise programme on the prevention of falls in older adult: A systematic review

Objective

To improve the quality of life of older adult in their later years, by increasing the physical activity participation of older adult, the occurrence of falls accident scores in older adult can be prevented. This paper comprehensively summarizes the origin, development, participation forms, and fitness effects of the Otago exercise program (OEP).

Methods

Using PubMed, web of science, CNKI, dimensional spectrum, and other databases, search for research papers from 2005 to April 2021 by using keywords such as Otago project exercise; aged, Fall; Cognitive function, Balance ability, Lower limb strength, Fall efficiency, and so on. PEDro Scale was used to check the quality of the literatures.

Results

A total of 34 papers were included after searching for kinds of literature related to the subject of this paper and after careful review by researchers.

Conclusions

Otago exercise programme is beneficial to improve the cognitive function of older adult, enhance their lower limb muscle strength and dynamic and static balance ability, and then improve the gait stability and posture control ability of older adult, which has significant positive benefits for the prevention of falls in older adult. OEP is helpful to improve the falling efficiency of older adult, help older adult overcome the fear of falling, and form a positive emotion of "exercise improves exercise," to reduce the harm caused by sedentary behavior and the incidence of depression and improve their subjective wellbeing. Although OEP has significant positive effects on improving the health and physical fitness of older adult, preventing falls, and restoring clinical function, the corresponding neural mechanism for preventing falls is not very clear. At the same time, how OEP can be combined with emerging technologies to maximize its benefits needs to be further discussed in the future.

The Correlation Between Falls and Cognitive Frailty in Elderly Individuals With Hypertension in a Chinese Community

Background

Cognitive frailty refers to the presence of both physical frailty and mild cognitive impairment without simultaneous diagnosis of Alzheimer's disease or other dementia. Epidemiological studies have confirmed the correlation between falls and cognitive frailty, but no study has investigated the relationship between fall risk and cognitive frailty in hypertensive elderly Chinese individuals.

Methods

From December 2020 to March 2021, during face-to-face interviews, community-dwelling elderly individuals with hypertension aged 60~89 in Pudong New Area, Shanghai, were evaluated for cognitive frailty, fall history, and depression, and sociodemographic characteristics were collected. Logistic regression was used to analyze the correlation between falls and cognitive frailty.

Results

A total of 305 elderly people were investigated in this study, and 173 (56.7%, 95% CI =51.2%~62.2%) reported falling once or more in the previous year. Cognitive frailty is closely related to falls and was an independent risk factor for falls (OR = 2.661, 95% CI = 1.063~6.659). Other risk factors included old age (OR = 4.306, 95% CI = 1.852~10.013), female sex (OR = 1.988, 95% CI = 1.185~3.335) and depression (OR = 2.936, 95% CI = 1.069~8.060).

Conclusion

Cognitive frailty is an important risk factor for falls in elderly individuals with hypertension in Chinese communities.

Lifespan extension with preservation of hippocampal function in aged system xc--deficient male mice

The cystine/glutamate antiporter system x_c^- has been identified as the major source of extracellular glutamate in several brain regions as well as a modulator of neuroinflammation, and genetic deletion of its specific subunit xCT (xCT^-/-) is protective in mouse models for age-related neurological disorders. However, the previously observed oxidative shift in the plasma cystine/cysteine ratio of adult xCT^-/- mice led to the hypothesis that system x_c^- deletion would negatively affect life- and healthspan. Still, till now the role of system x_c^- in physiological aging remains unexplored. We therefore studied the effect of xCT deletion on the aging process of mice, with a particular focus on the immune system, hippocampal function, and cognitive aging. We observed that male xCT^-/- mice have an extended lifespan, despite an even more increased plasma cystine/cysteine ratio in aged compared to adult mice. This oxidative shift does not negatively impact the general health status of the mice. On the contrary, the age-related priming of the innate immune system, that manifested as increased LPS-induced cytokine levels and hypothermia in xCT^+/+ mice, was attenuated in xCT^-/- mice. While this was associated with only a very moderate shift towards a more anti-inflammatory state of the aged hippocampus, we observed changes in the hippocampal metabolome that were associated with a preserved hippocampal function and the retention of hippocampus-dependent memory in male aged xCT^-/- mice. Targeting system x_c^- is thus not only a promising strategy to prevent cognitive decline, but also to promote healthy aging.

Prevalence and Risk Factors for Cognitive Frailty in Aging Hypertensive Patients in China

Hypertension is one of the most common chronic diseases and a major risk factor for stroke, myocardial infarction and cardiovascular death. Cognitive frailty is an important predictor of all-cause mortality and dementia in aging individuals. Hypertension is closely related to cognitive frailty and these two conditions often coexist in aging individuals. Few studies have explored the relationship between hypertension and cognitive frailty in the Chinese population. This study investigates the epidemiological characteristics of and factors related to cognitive frailty in aging Chinese patients with hypertension. In total, cognitive function, weakness, social support, depression and sociodemographic were assessed in 305 participants aged 60 and over. Univariate and multivariate logistic regression models were constructed. The prevalence of cognitive frailty in aging Chinese hypertensive patients was 9.8% (95% CI = 6.4–13.2%). After adjusting for confounding variables, logistic regression showed that the course of hypertension (6–10 years, OR = 8.588, 95% CI = 1.608–45.859;course of more than 10 years, OR = 9.020, 95%CI = 1.854–43.892), multimorbidity (OR = 11.231, 95% CI = 2.912–43.322), depression (OR = 6.917, 95% CI = 2.424–19.738) and social support (OR = 0.187, 95% CI = 0.071–0.492) were independently associated with cognitive frailty. The prevalence of cognitive frailty in aging patients with hypertension in China should not be ignored. The course of hypertension, multimorbidity and depression are the risk factors of cognitive frailty in the aging population and a better level of social support is the protective factor for cognitive frailty.

Otago exercise programme for physical function and mental health among older adults with cognitive frailty during COVID-19: A randomised controlled trial

AIMS AND OBJECTIVES

Quarantine during the COVID-19 pandemic resulted in longer-term sedentary behaviours and mental health problems. Our study aimed to evaluate the impact of the Otago exercise programme (OEP) on physical function and mental health among elderly with cognitive frailty during COVID-19.

BACKGROUND

Lockdowns and restrictions during the COVID-19 pandemic result in longer-term sedentary behaviours related disease and mental problem. Older people with cognitive frailty are more vulnerable to be influenced. Timely intervention may achieve better outcomes, OEP exercise was designed as a balance and muscle-strengthening programme for elderly people.

DESIGN

A parallel-group, assessor-blinded randomised controlled trial was performed according to CONSORT guidelines.

METHODS

This study was conducted from July 2020 to October 2020 among 62 elderly people with cognitive frailty from a nursing home. Participants were randomly divided into an OEP group (n = 31) or a control group (n = 31). Both groups received sleep- and diet-related health education. The OEP group also received a 12-week group exercise programme. The Five Times Sit to Stand Test (FTSST), Berg Balance Scale (BBS), and Timed Up and Go Test (TUGT) were used to assess physical function. The Geriatric Depression Scale-15 (GDS-15) and the 12-Item Short Form Health Survey Mental Component Summary (SF-12 MCS) were used to assess mental health. Outcomes were measured at 6 and 12 weeks.

RESULTS

Physical function and mental health were similar in the two groups at baseline. At 12 weeks, the OEP group (difference in change from baseline: FTSST, -2.78; TUGT, -3.73; BBS, 2.17; GDS-15, -0.72; SF-12 MCS, 2.58; all p < .001) exhibited significantly greater improvements than the control group (difference in change from baseline: FTSST, 1.55; TUGT, 1.66; BBS, -0.10; GDS-15, 1.07; SF-12 MCS, -5.95; all p < .001).

CONCLUSION

Our findings showed the OEP group had better physical function and mental health outcomes than the control group. OEP can be used to improve the physical and mental function among elderly people with cognitive frailty during the COVID-19 pandemic.

RELEVANCE TO CLINICAL PRACTICE

Otago exercise program intervention programmes should be implemented to improve physical function for cognitive frailty elderly to reduce the harm of longer-term sedentary behaviours, and to ruduce depression symptom and improve mental health, particularly during COVID-19 pandemic period.

The Effects of Elaeagnus angustifolia L. on the Thyroid-Stimulating Hormone, Dehydroepiandrosterone-Sulfate, Prolactin and Cortisol Levels in Post-Menopausal Women: A Double-Blind, Randomized, and Placebo-Controlled Study

Menopause is the last menstrual period associated with a decline in ovarian steroid secretion and follicular loss. Hormone profile changes during menopause include a decrease in the production of estrogen, dehydroepiandrosterone (DHEA), and prolactin (PRL), and an increase in thyroid-stimulating hormone (TSH) and cortisol. Herbal medicines are considered as alternatives to hormone therapy. The studies on postmenopausal women have shown that Elaeagnus angustifolia L. (called "Senjed" in Persian) has some efficacy in improving sex hormone and lipid profiles, joint pain, and cardiovascular function, as the decrease in luteinizing hormone, low-density lipoprotein, and heart rate was significant. The aim of the present study was to evaluate the effects of E. angustifolia on TSH, DHEA-S, PRL, and cortisol levels and their ratios in postmenopausal women. It is assumed that the eventual effects of hormones on the brain and other tissues are determined by the balance between interdependent hormones. In the present randomized double-blinded placebo-controlled trial (https://en.irct.ir/search/result?query=IRCT20170227032795N4), fifty-eight postmenopausal women were randomly assigned to one of two medicinal herb (15 g of the whole E. angustifolia fruit powder) and placebo (7.5 g isomalt + 7.5 g cornstarch) groups. After 10 weeks of the treatment, the serum levels of TSH, DHEA-S, PRL, cortisol hormones, and their ratios were measured. The increase in the TSH, and cortisol levels, and cortisol/DHEA-S ratio and the decrease in prolactin and DHEA-S and the PRL/TSH, PRL/cortisol, and DHEA-S/TSH ratios after E. angustifolia consumption were significant only based on within-group but not on the between-group analysis. Based on between-group analyses, the changes in the hormone profile were not significant in the placebo group. According to Iranian tradition and folklore, E. angustifolia fruit is a symbol of female fertility. Therefore, its consumption is highly recommended to maintain health in the elderly, especially women. However, the observed outcomes about the effect of E. angustifolia on menopause were not completely in line with the Iranian folklore. E. angustifolia consumption did not significantly affect the hormone profile and ratios at the end of the ten-week trial, possibly due to the small sample size, short time, and the fact that our participants were postmenopausal women.

Heterogeneous Influence of Frailty Phenotypes in Age-Related Hearing Loss and Tinnitus in Chinese Older Adults: An Explorative Study

Background

Fried physical frailty, with mobility frailty and non-motor frailty phenotypes, is a heterogeneous syndrome. The coexistence of the two phenotypes and cognitive impairment is referred to as cognitive frailty (CF). It remains unknown whether frailty phenotype has a different association with hearing loss (HL) and tinnitus.

Methods

Of the 5,328 community-dwelling older adults, 429 participants aged ≥58 years were enrolled in the study. The participants were divided into robust, mobility, and non-mobility frailty, mobility and non-mobility CF (subdivided into reversible and potentially reversible CF, RCF, and PRCF), and cognitive decline [subdivided into mild cognitive impairment (MCI) and pre-MCI] groups. The severity and presentations of HL and/or tinnitus were used as dependent variables in the multivariate logistic or nominal regression analyses with forward elimination adjusted for frailty phenotype stratifications and other covariates.

Results

Patients with physical frailty (mobility frailty) or who are robust were found to have lower probability of developing severe HL and tinnitus, and presented HL and/or tinnitus than those with only cognitive decline, or CF. Patients with RCF and non-mobility RCF had higher probability with less HL and tinnitus, and the presentation of HL and/or tinnitus than those with PRCF and mobility RCF. Other confounders, age, cognitive and social function, cardiovascular disease, depression, and body mass index, independently mediated the severity of HL and tinnitus, and presented HL and/or tinnitus.

Conclusion

Frailty phenotypes have divergent association with HL and tinnitus. Further research is required to understand the differential mechanisms and the personalized intervention of HL and tinnitus.

Clinical Trial Registration

ClinicalTrials.gov identifier, NCT2017K020.

Mesenchymal Stem Cell Transplantation for the Treatment of Cognitive Frailty

As life expectancy increases, frailty and cognitive impairment have become major factors influencing healthy aging in elderly individuals. Frailty is a complicated clinical condition characterized by decreased physiological reserve and multisystem abnormalities. Cognitive frailty is a subtype of frailty that has aroused widespread concern among the scientific community and public health organizations. We herein review the pathogenesis of cognitive frailty, such as chronic inflammatory response, immunological hypofunction, imbalanced oxidative stress, reduced regenerative function, endocrine dysfunction, and energy metabolism disorder. Although existing interventions show some therapeutic effects, they do not meet the current clinical needs. To date, studies using stem cell technology for treating age-related diseases have achieved remarkable success. This suggests the possibility of applying stem cell treatment to cognitive frailty. We analyzed stem cell-based strategies for targeting anti-inflammation, antioxidation, regeneration, and immunoregulation using mesenchymal stem cells, as well as potential therapeutic targets for cognitive frailty. Based on this investigation, we propose a highly effective and low-cost stem cell-based replacement strategy. However, there is a lack of comprehensive research on the prospect of stem cell transplantation for improving cognitive frailty. In this review, we aim to provide the scientific background and a theoretical basis for testing cell therapy in future research.

Understanding the Physiological Links Between Physical Frailty and Cognitive Decline

Declines in both physical and cognitive function are associated with increasing age. Understanding the physiological link between physical frailty and cognitive decline may allow us to develop interventions that prevent and treat both conditions. Although there is significant epidemiological evidence linking physical frailty to cognitive decline, a complete understanding of the underpinning biological basis of the two disorders remains fragmented. This narrative review discusses insights into the potential roles of chronic inflammation, impaired hypothalamic-pituitary axis stress response, imbalanced energy metabolism, mitochondrial dysfunction, oxidative stress, and neuroendocrine dysfunction linking physical frailty with cognitive decline. We highlight the importance of easier identification of strategic approaches delaying the progression and onset of physical frailty and cognitive decline as well as preventing disability in the older population.

Identification of five frailty profiles in community-dwelling individuals aged 50-75: A latent class analysis of the SUCCEED survey data

OBJECTIVES

We sought to identify frailty profiles in individuals aged 50-75 by considering frailty as an unobservable latent variable in a latent class analysis (LCA).

STUDY DESIGN

589 prospectively enrolled community-dwelling individuals aged 50-75 (median: 61.7 years) had undergone a standardized, multidomain assessment in 2010-2015. Adverse health outcomes (non-accidental falls, fractures, unplanned hospitalizations, and death) that had occurred since the assessment were recorded in 2016-2017.

MAIN OUTCOME MEASURES

The LCA used nine indicators (unintentional weight loss, relative slowness, weakness, impaired balance, osteoporosis, impaired cognitive functions, executive dysfunction, depression, and hearing impairment) and three covariates (age, gender, and consultation for health complaints). The resulting profiles were characterized by the Fried phenotype and adverse health outcomes.

RESULTS

We identified five profiles: "fit" (LC1, 29.7% of the participants; median age: 59 years); "weight loss, relative slowness, and osteoporosis" (LC2, 33.2%; 63 years); "weakness and osteopenia" (LC3, 21.9%; 60 years); "impaired physical and executive functions" (LC4, 11%; 67 years); and "impaired balance, cognitive functions, and depression" (LC5, 4.3%; 70 years). Almost all members of LC3 and LC4 were female, and were more likely than members of other profiles to have a frail or pre-frail Fried phenotype. Non-accidental falls were significantly more frequent in LC4. LC5 (almost all males) had the highest number of comorbidities and cardiovascular risk factors but none was frail.

CONCLUSIONS

Our data-driven approach covered most geriatric assessment domains and identified five frailty profiles. With a view to tailoring interventions and prevention, frailty needs to be detected among young seniors.

The effects of both age and sex on irisin levels in paired plasma and cerebrospinal fluid in healthy humans

BACKGROUND

Adipo-myokine irisin has important effects on the metabolism and functioning of multiple tissues and organs. However, the effects of aging and sex on irisin levels in cerebrospinal fluid (CSF) and on circulation have not been comprehensively studied.

OBJECTIVE

To investigate whether aging and sex can affect irisin levels in both CSF and plasma; to determine whether CSF irisin uptake involves a saturable transport mechanism.

DESIGN AND METHODS

In the present study, the irisin levels in paired CSF and plasma samples drawn from 71 healthy individuals were used to investigate effects by using commercial ELISA kits and mass spectrometry.

RESULTS

Multiple linear regression analysis results showed that CSF irisin levels are positively correlated with the CSF/plasma irisin ratio and age and that these levels present a reverse correlation with BMI. Age-related increases in CSF levels are validated by using ELISA and mass spectrometry. Higher plasma irisin levels are observed in men than women. CSF and plasma irisin levels are nonlinearly associated with the CSF/plasma irisin ratio, BMI, age and F scores. The CSF/plasma irisin ratio is U-shaped and associated with age.

CONCLUSIONS

There might be an age-related increase in irisin levels in the cerebrospinal fluid of healthy humans. Circulating irisin levels are higher in males than in females in the healthy population. A saturable mechanism might be involved in mediating the transport of circulating irisin across the blood-brain barrier. Factors shaping irisin levels for both circulation and the CSF of healthy humans must be further defined in future experiments.

Manual dexterity in young and healthy older adults. 1. Age- and gender-related differences in unimanual and bimanual performance

This study aimed to better characterize age-related differences in dexterity by using an integrative approach where movement times and kinematics were measured for both hands. Forty-five young (age 19-31) and 55 healthy older adults (age 60-88) were evaluated during unimanual and bimanual performance of the Purdue Pegboard Test. Gender effects were also assessed. From video-recorded data, movement times and kinematics were obtained for reaching, grasping, transport, and inserting. Results showed that older adults had longer movement times for grasping and inserting with the right hand, and across all movements with the left hand. Kinematic differences were found in path length, linear, and angular velocity. The patterns of slowing were similar in unimanual and bimanual tasks. Gender effects showed more slowing in older males than older females. Age differences in dexterity not only comprise slowing of movements but also kinematic alterations. The importance of gender in hand function was demonstrated.