DNA methylation and the epigenetic clock in relation to physical frailty in older people: the Lothian Birth Cohort 1936

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.

Can geroscience be translated into healthcare?

As an introduction to this special issue on geroscience, the present work focuses on the complexity of disentangling biomolecular mechanisms of aging from biopsychosocial causes of accelerated aging. Due to this complexity, the biomolecular aging hallmarks of frailty and multimorbidity as predominant aging phenotypes in geriatrics reflect single aspects of the aging process. A possible approach to facilitate the integration of geroscience into healthcare might be to consider aging as the dynamic ratio between damage accumulation at the molecular and cellular level and resilience as strategies that prevent or repair such damage. There is a large body of evidence to show that geroscience has the potential to change healthcare; however, reaching a consensus and translating the best tool to measure aging needs more research on 1) the sensitivity of biomarkers to interventions and 2) the relationship between changes in biomarkers and changes in health trajectories.

Revealing the Hidden Impacts: Insights into Biological Aging and Long-Term Effects in Pauci- and Asymptomatic COVID-19 Healthcare Workers

This study explores the role of inflammation and oxidative stress, hallmarks of COVID-19, in accelerating cellular biological aging. We investigated early molecular markers-DNA methylation age (DNAmAge) and telomere length (TL)-in blood leukocytes, nasal cells (NCs), and induced sputum (IS) one year post-infection in pauci- and asymptomatic healthcare workers (HCWs) infected during the first pandemic wave (February-May 2020), compared to COPD patients, model for "aged lung". Data from questionnaires, Work Ability Index (WAI), blood analyses, autonomic cardiac balance assessments, heart rate variability (HRV), and pulmonary function tests were collected. Elevated leukocyte DNAmAge significantly correlated with advancing age, male sex, daytime work, and an aged phenotype characterized by chronic diseases, elevated LDL and glycemia levels, medications affecting HRV, and declines in lung function, WAI, lymphocyte count, hemoglobin levels, and HRV (p < 0.05). Increasing age, LDL levels, job positions involving intensive patient contact, and higher leukocyte counts collectively contributed to shortened leukocyte TL (p < 0.05). Notably, HCWs exhibited accelerated biological aging in IS cells compared to both blood leukocytes (p ≤ 0.05) and NCs (p < 0.001) and were biologically older than COPD patients (p < 0.05). These findings suggest the need to monitor aging in pauci- and asymptomatic COVID-19 survivors, who represent the majority of the general population.

Value of combining biological age with assessment of individual frailty to optimize management of cancer treated with targeted therapies: model of chronic myeloid leukemia treated with tyrosine kinase inhibitors (BIO-TIMER trial)

BACKGROUND

In the era of targeted therapies, the influence of aging on cancer management varies from one patient to another. Assessing individual frailty using geriatric tools has its limitations, and is not appropriate for all patients especially the youngest one. Thus, assessing the complementary value of a potential biomarker of individual aging is a promising field of investigation. The chronic myeloid leukemia model allows us to address this question with obvious advantages: longest experience in the use of tyrosine kinase inhibitors, standardization of therapeutic management and response with minimal residual disease and no effect on age-related diseases. Therefore, the aim of the BIO-TIMER study is to assess the biological age of chronic myeloid leukemia or non-malignant cells in patients treated with tyrosine kinase inhibitors and to determine its relevance, in association or not with individual frailty to optimize the personalised management of each patient.

METHODS

The BIO-TIMER study is a multi-center, prospective, longitudinal study aiming to evaluate the value of combining biological age determination by DNA methylation profile with individual frailty assessment to personalize the management of chronic myeloid leukemia patients treated with tyrosine kinase inhibitors. Blood samples will be collected at diagnosis, 3 months and 12 months after treatment initiation. Individual frailty and quality of life will be assess at diagnosis, 6 months after treatment initiation, and then annually for 3 years. Tolerance to tyrosine kinase inhibitors will also be assessed during the 3-year follow-up. The study plans to recruit 321 patients and recruitment started in November 2023.

DISCUSSION

The assessment of individual frailty should make it possible to personalize the treatment and care of patients. The BIO-TIMER study will provide new data on the role of aging in the management of chronic myeloid leukemia patients treated with tyrosine kinase inhibitors, which could influence clinical decision-making.

TRIAL REGISTRATION

ClinicalTrials.gov , ID NCT06130787; registered on November 14, 2023.

The epigenetics of frailty

The conceptual change of frailty, from a physical to a biopsychosocial phenotype, expanded the field of frailty, including social and behavioral domains with critical interaction between different frailty models. Environmental exposures - including physical exercise, psychosocial factors and diet - may play a role in the frailty pathophysiology. Complex underlying mechanisms involve the progressive interactions of genetics with epigenetics and of multimorbidity with environmental factors. Here we review the literature on possible mechanisms explaining the association between epigenetic hallmarks (i.e., global DNA methylation, DNA methylation age acceleration and microRNAs) and frailty, considered as biomarkers of aging. Frailty could be considered the result of environmental epigenetic factors on biological aging, caused by conflicting DNA methylation age and chronological age.

Sex differences in frailty among older adults

By definition, aging is a natural, gradual and continuous process. On the other hand, frailty reflects the increase in vulnerability to stressors and shortens the time without disease (health span) while longevity refers to the length of life (lifespan). The average life expectancy has significantly increased during the last few decades. A longer lifespan has been accompanied by an increase in frailty and decreased independence in older adults, with major differences existing between men and women. For example, women tend to live longer than men but also experience higher rates of frailty and disability. Sex differences prevent optimization of lifestyle interventions and therapies to effectively prevent frailty. Sex differences in frailty and aging are rooted in a complex interplay between uncontrollable (genetic, epigenetic, physiological), and controllable factors (psychosocial and lifestyle factors). Thus, understanding the underlying causes of sex differences in frailty and aging is essential for developing personalized interventions to promote healthy aging and improve quality of life in older men and women. In this review, we have discussed the key contributors and knowledge gaps related to sex differences in aging and frailty.

Epigenetic signature of human immune aging in the GESTALT study

Age-associated DNA methylation in blood cells convey information on health status. However, the mechanisms that drive these changes in circulating cells and their relationships to gene regulation are unknown. We identified age-associated DNA methylation sites in six purified blood-borne immune cell types (naive B, naive CD4+ and CD8+ T cells, granulocytes, monocytes, and NK cells) collected from healthy individuals interspersed over a wide age range. Of the thousands of age-associated sites, only 350 sites were differentially methylated in the same direction in all cell types and validated in an independent longitudinal cohort. Genes close to age-associated hypomethylated sites were enriched for collagen biosynthesis and complement cascade pathways, while genes close to hypermethylated sites mapped to neuronal pathways. In silico analyses showed that in most cell types, the age-associated hypo- and hypermethylated sites were enriched for ARNT (HIF1β) and REST transcription factor (TF) motifs, respectively, which are both master regulators of hypoxia response. To conclude, despite spatial heterogeneity, there is a commonality in the putative regulatory role with respect to TF motifs and histone modifications at and around these sites. These features suggest that DNA methylation changes in healthy aging may be adaptive responses to fluctuations of oxygen availability.

Biological Age Acceleration and Motoric Cognitive Risk Syndrome

OBJECTIVE

Motoric cognitive risk (MCR) syndrome, a predementia syndrome characterized by slow gait and subjective cognitive concerns, is associated with multiple age-related risk factors. We hypothesized that MCR is associated with biological age acceleration. We examined the associations of biological age acceleration with MCR, and mortality risk in MCR cases.

METHODS

Biological age was determined using proteomic and epigenetic clocks in participants aged 65 years and older in the LonGenity study (N = 700, females = 57.9%) and Health and Retirement Study (HRS; N = 1,043, females = 57.1%) cohorts. Age acceleration (AgeAccel) was operationally defined as the residual from regressing predicted biological age (from both clocks separately) on chronological age. Association of AgeAccel with incident MCR in the overall sample as well as with mortality risk in MCR cases was examined using Cox models and reported as hazard ratios (HRs).

RESULTS

AgeAccel scores derived from a proteomic clock were associated with prevalent MCR (odds ratio adjusted for age, gender, education years, and chronic illnesses [aOR] = 1.36, 95% confidence interval [CI] = 1.09-1.71) as well as predicted incident MCR (HR = 1.19, 95% CI = 1.00-1.41) in the LonGenity cohort. In HRS, the association of AgeAccel using an epigenetic clock with prevalent MCR was confirmed (aOR = 1.47, 95% CI = 1.16-1.85). Participants with MCR and accelerated aging (positive AgeAccel score) were at the highest risk for mortality in both LonGenity (HR = 3.38, 95% CI = 2.01-5.69) and HRS (HR = 2.47, 95% CI = 1.20-5.10).

INTERPRETATION

Accelerated aging predicts risk for MCR, and is associated with higher mortality in MCR patients. ANN NEUROL 2023;93:1187-1197.

The effect of high polycyclic aromatic hydrocarbon exposure on biological aging indicators

BACKGROUND

Aging represents a serious health and socioeconomic concern for our society. However, not all people age in the same way and air pollution has been shown to largely impact this process. We explored whether polycyclic aromatic hydrocarbons (PAHs), excellent fossil and wood burning tracers, accelerate biological aging detected by lymphocytes DNA methylation age (DNAmAge) and telomere length (TL), early nuclear DNA (nDNA) hallmarks of non-mitotic and mitotic cellular aging, and mitochondrial DNA copy number (mtDNAcn).

METHODS

The study population consisted of 49 male noncurrent-smoking coke-oven workers and 44 matched controls. Occupational and environmental sources of PAH exposures were evaluated by structured questionnaire and internal dose (urinary 1-pyrenol). We estimated Occup_PAHs, the product of 1-pyrenol and years of employment as coke-oven workers, and Environ_PAHs, from multiple items (diet, indoor and outdoor). Biological aging was determined by DNAmAge, via pyrosequencing, and by TL and mtDNAcn, via quantitative polymerase chain reaction. Genomic instability markers in lymphocytes as target dose [anti-benzo[a]pyrene diolepoxide (anti-BPDE)-DNA adduct], genetic instability (micronuclei), gene-specific (p53, IL6 and HIC1) and global (Alu and LINE-1 repeats) DNA methylation, and genetic polymorphisms (GSTM1) were also evaluated in the latent variable nDNA_changes. Structural equation modelling (SEM) analysis evaluated these multifaceted relationships.

RESULTS

In univariate analysis, biological aging was higher in coke-oven workers than controls as detected by higher percentage of subjects with biological age older than chronological age (AgeAcc ≥ 0, p = 0.007) and TL (p = 0.038), mtDNAcn was instead similar. Genomic instability, i.e., genotoxic and epigenetic alterations (LINE-1, p53 and Alu) and latent variable nDNA_changes were higher in workers (p < 0.001). In SEM analysis, DNAmAge and TL were positively correlated with Occup_PAHs (p < 0.0001). Instead, mtDNAcn is positively correlated with the latent variable nDNA_changes (p < 0.0001) which is in turn triggered by Occup_PAHs and Environ_PAHs.

CONCLUSIONS

Occupational PAHs exposure influences DNAmAge and TL, suggesting that PAHs target both non-mitotic and mitotic mechanisms and made coke-oven workers biologically older. Also, differences in mtDNAcn, which is modified through nDNA alterations, triggered by environmental and occupational PAH exposure, suggested a nuclear-mitochondrial core-axis of aging. By decreasing this risky gerontogenic exposure, biological aging and the consequent age-related diseases could be prevented.

Profiling placental DNA methylation associated with maternal SSRI treatment during pregnancy

Selective serotonin reuptake inhibitors (SSRIs) for treatment of prenatal maternal depression have been associated with neonatal neurobehavioral disturbances, though the molecular mechanisms remain poorly understood.  In utero exposure to SSRIs may affect DNA methylation (DNAme) in the human placenta, an epigenetic mark that is established during development and is associated with gene expression. Chorionic villus samples from 64 human placentas were profiled with the Illumina MethylationEPIC BeadChip; clinical assessments of maternal mood and SSRI treatment records were collected at multiple time points during pregnancy. Case distribution was 20 SSRI-exposed cases and 44 SSRI non-exposed cases. Maternal depression was defined using a mean maternal Hamilton Depression score > 8 to indicate symptomatic depressed mood ("maternally-depressed"), and we further classified cases into SSRI-exposed, maternally-depressed (n = 14); SSRI-exposed, not maternally-depressed (n = 6); SSRI non-exposed, maternally-depressed (n = 20); and SSRI non-exposed, not maternally-depressed (n = 24). For replication, Illumina 450K DNAme profiles were obtained from 34 additional cases from an independent cohort (n = 17 SSRI-exposed, n = 17 SSRI non-exposed). No CpGs were differentially methylated at FDR < 0.05 comparing SSRI-exposed to non-exposed placentas, in a model adjusted for mean maternal Hamilton Depression score, or in a model restricted to maternally-depressed cases with and without SSRI exposure. However, at a relaxed threshold of FDR < 0.25, five CpGs were differentially methylated (|Δβ| > 0.03) by SSRI exposure status. Four were covered by the replication cohort measured by the 450K array, but none replicated. No CpGs were differentially methylated (FDR < 0.25) comparing maternally depressed to not depressed cases. In sex-stratified analyses for SSRI-exposed versus non-exposed cases (females n = 31; males n = 33), three additional CpGs in females, but none in males, were differentially methylated at the relaxed FDR < 0.25 cut-off. We did not observe large-scale alterations of DNAme in placentas exposed to maternal SSRI treatment, as compared to placentas with no SSRI exposure. We also found no evidence for altered DNAme in maternal depression-exposed versus depression non-exposed placentas. This novel work in a prospectively-recruited cohort with clinician-ascertained SSRI exposure and mood assessments would benefit from future replication.

Frailty biomarkers under the perspective of geroscience: A narrative review

Cellular and molecular aging biomarkers might contribute to identify at-risk individuals for frailty before overt clinical manifestations appear. Although studies on the associations of aging biomarkers and frailty exist, no investigation has gathered this information using a structured framework for identifying aging biomarkers; as a result, the evidence on frailty and aging biomarkers is diffuse and incomplete. Therefore, this narrative review aimed to gather information on the associations of the hallmarks of aging and frailty under the perspective of geroscience. The literature on human studies on this topic is sparse and mainly composed of cross-sectional investigations performed in small study samples. The main putative aging biomarkers associated to frailty were: mitochondrial DNA copy number (genomic instability and mitochondrial dysfunction), telomere length (telomere attrition), global DNA methylation (epigenetic alterations), Hsp70 and Hsp72 (loss of proteostasis), IGF-1 and SIRT1 (deregulated nutrient-sensing), GDF-15 (mitochondrial dysfunction, cellular senescence and altered intercellular communication), CD4 + and CD8 + cell percentages (cellular senescence), circulating osteogenic progenitor (COP) cells (stem cell exhaustion), and IL-6, CRP and TNF-alpha (altered intercellular communication). IGF-1, SIRT1, GDF-15, IL-6, CRP and TNF-alpha presented more evidence among these biomarkers, highlighting the importance of inflammation and nutrient sensing on frailty. Further longitudinal studies investigating biomarkers across the hallmarks of aging would provide valuable information on this topic.

A review of epigenetics and its association with ageing of muscle and bone

Ageing is defined as the 'increasing frailty of an organism with time that reduces the ability of that organism to deal with stress'. It has been suggested that epigenetics may underlie the observation that some individuals appear to age faster than others. Epigenetics is the study of changes which occur in an organism due to changes in expression of the genetic code rather than changes to the genetic code itself; that is, epigenetic mechanisms impact upon the function of DNA without changing the DNA sequence. It is important to recognise that epigenetic changes, in contrast to genetic changes, can vary according to different cell types and therefore can demonstrate significant tissue-specificity. There are different types of epigenetic mechanisms: histone modification, non-coding RNAs and DNA methylation. Epigenetic clocks have been developed using statistical techniques to identify the optimal combination of CpG sites (from methylation arrays) to correlate with chronological age. This review considers how epigenetic factors may affect rates of ageing of muscle and bone and provides an overview of current understanding in this area. We discuss studies using first-generation epigenetic clocks, as well as the second-generation iterations, which appear to show stronger associations with the ageing muscle phenotype. We also review epigenome-wide association studies that have been performed in various tissues examining relationships with osteoporosis and fracture. It is hoped that an understanding of this area will lead to interventions that might prevent or reduce rates of musculoskeletal ageing in later life.

Improving the prognostic value of multimorbidity through the integration of selected biomarkers to the comprehensive geriatric assessment: An observational retrospective monocentric study

Background

Multimorbidity (MM) burdens individuals and healthcare systems, since it increases polypharmacy, dependency, hospital admissions, healthcare costs, and mortality. Several attempts have been made to determine an operational definition of MM and to quantify its severity. However, the lack of knowledge regarding its pathophysiology prevented the estimation of its severity in terms of outcomes. Polypharmacy and functional impairment are associated with MM. However, it is unclear how inappropriate drug decision-making could affect both conditions. In this context, promising circulating biomarkers and DNA methylation tools have been proposed as potential mortality predictors for multiple age-related diseases. We hypothesize that a comprehensive characterization of patients with MM that includes the measure of epigenetic and selected circulating biomarkers in the medical history, in addition to the functional capacity, could improve the prognosis of their long-term mortality.

Methods

This monocentric retrospective observational study was conducted as part of a project funded by the Italian Ministry of Health titled “imProving the pROgnostic value of MultimOrbidity through the inTegration of selected biomarkErs to the comprehensive geRiatric Assessment (PROMOTERA).” This study will examine the methylation levels of thousands of CpG sites and the levels of selected circulating biomarkers in the blood and plasma samples of older hospitalized patients with MM (n = 1,070, age ≥ 65 years) recruited by the Reportage Project between 2011 and 2019. Multiple statistical approaches will be utilized to integrate newly measured biomarkers into clinical, demographic, and functional data, thus improving the prediction of mortality for up to 10 years.

Discussion

This study's results are expected to: (i) identify the clinical, biological, demographic, and functional factors associated with distinct patterns of MM; (ii) improve the prognostic accuracy of MM patterns in relation to death, hospitalization-related outcomes, and onset of new comorbidities; (iii) define the epigenetic signatures of MM; (iv) construct multidimensional algorithms to predict negative health outcomes in both the overall population and specific disease and functional patterns; and (v) expand our understanding of the mechanisms underlying the pathophysiology of MM.

Derivation and validation of an epigenetic frailty risk score in population-based cohorts of older adults

DNA methylation (DNAm) patterns in peripheral blood have been shown to be associated with aging related health outcomes. We perform an epigenome-wide screening to identify CpGs related to frailty, defined by a frailty index (FI), in a large population-based cohort of older adults from Germany, the ESTHER study. Sixty-five CpGs are identified as frailty related methylation loci. Using LASSO regression, 20 CpGs are selected to derive a DNAm based algorithm for predicting frailty, the epigenetic frailty risk score (eFRS). The eFRS exhibits strong associations with frailty at baseline and after up to five-years of follow-up independently of established frailty risk factors. These associations are confirmed in another independent population-based cohort study, the KORA-Age study, conducted in older adults. In conclusion, we identify 65 CpGs as frailty-related loci, of which 20 CpGs are used to calculate the eFRS with predictive performance for frailty over long-term follow-up.

Epigenetic age stratifies the risk of blood pressure elevation related to short-term PM2.5 exposure in older adults

BACKGROUND

Exposure to fine particulate matter (PM_2.5) is a prominent risk factor for cardiovascular aging in older adults and causes mild syndromes or other comorbidities in otherwise healthy older adults. Accordingly, a precise tool for PM_2.5 exposure risk stratification is urgently needed. We aimed to address this need by comparing the performances of seven types of epigenetic age and chronological age to classify the effects of short-term PM_2.5 exposure on blood pressure (BP), a typical clinical surrogate marker of cardiovascular aging.

METHODS

We conducted a panel study of the Chinese healthy adults aged 60-69 years through five monthly visits. Personal PM_2.5 exposures were measured using wearable monitoring devices for three consecutive days, and DNA methylation was determined by the Illumina MethylationEPIC BeadChip using blood samples collected at each visit. Systolic BP, diastolic BP, mean arterial pressure and pulse pressure were measured by the electronic BP monitor. Linear mixed models with interaction terms between PM_2.5 and different ages were used to assess their potential usefulness for stratification.

RESULTS

DNAmPhenoAge, Skin & blood clock, DNAmGrimAge acceleration, and DunedinPoAm had significant modifying effects on the relationship between PM_2.5 and BP. For instance, a 10-μg/m³ increase in the 72-h moving mean PM_2.5 was significantly associated with 0.30% (95% CI: 0.10%, 0.51%) and -0.07% (95% CI: -0.32%, 0.18%) increases in systolic BP at higher and lower DNAmPhenoAge acceleration, respectively. Joint models further revealed that using a combination of epigenetic ages could more precisely stratify the effect of PM_2.5 on BP.

CONCLUSIONS

Our research indicates that epigenetic age may be a useful tool for evaluating the effect of short-term PM_2.5 exposure on cardiovascular aging status.

Frailty in individuals with depression, bipolar disorder and anxiety disorders: longitudinal analyses of all-cause mortality

BACKGROUND

Frailty is a medical syndrome that is strongly associated with mortality risk and an emerging global health burden. Mental disorders are associated with reduced life expectancy and elevated levels of frailty. In this study, we examined the mortality risk associated with frailty in individuals with a lifetime history of mental disorders compared to individuals without a history of mental disorders.

METHODS

The UK Biobank study recruited > 500,000 adults, aged 37-73, between 2006 and 2010. We derived the two most common albeit distinctive measures of frailty, the frailty phenotype and the frailty index. Individuals with lifetime depression, bipolar disorder or anxiety disorders were identified from multiple data sources. The primary outcome was all-cause mortality. We have also examined differences in frailty, separately by sex and age.

RESULTS

Analyses included up to 297,380 middle-aged and older adults with a median follow-up of 12.19 (interquartile range = 1.31) years, yielding 3,516,706 person-years of follow-up. We observed higher levels of frailty in individuals with mental disorders for both frailty measures. Standardised mean differences in the frailty index ranged from 0.66 (95% confidence interval [CI] 0.65-0.67) in individuals with anxiety disorders to 0.94 (95% CI 0.90-0.97) in individuals with bipolar disorder, compared to people without mental disorders. For key comparisons, individuals with a mental disorder had greater all-cause mortality hazards than the comparison group without mental disorders. The highest hazard ratio (3.65, 95% CI 2.40-5.54) was observed among individuals with bipolar disorder and frailty, relative to non-frail individuals without mental disorders.

CONCLUSIONS

Our findings highlight elevated levels of frailty across three common mental disorders. Frailty and mental disorders represent potentially modifiable targets for prevention and treatment to improve population health and life expectancy, especially where both conditions coexist.

Analysis of Epigenetic Age Acceleration and Healthy Longevity Among Older US Women

IMPORTANCE

Accelerated biological aging is associated with decreased physical capability and cognitive functioning, which are associated with increased risk of morbidity and mortality.

OBJECTIVE

We investigated associations between epigenetic age acceleration (EAA), a biomarker associated with aging, and healthy longevity among older women.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was a secondary analysis of participants in the Women's Health Initiative (WHI) who were eligible to survive to age 90 years by September 30, 2020. Participants were located in multiple centers. This study was restricted to women with genome-wide DNA methylation data, generated from baseline blood samples within 3 WHI ancillary studies. Median (IQR) follow-up times from baseline were 21.6 (19.6-22.9) years and 21.4 (19.8-22.7) years for women who survived to age 90 years with and without intact mobility, respectively, and 13.2 (8.8-16.7) for women who did not survive to age 90 years. Data were analyzed from December 2020 to July 2021.

EXPOSURES

EAA was estimated using 4 established "clocks": Horvath pantissue, Hannum, Pheno, and Grim.

MAIN OUTCOMES AND MEASURES

Using multinomial logistic regression, odds ratios (ORs) and 95% CIs were estimated for 3 healthy longevity outcomes for each clock: survival to age 90 years with intact mobility, survival to age 90 years without intact mobility, and no survival to age 90 years.

RESULTS

Among 1813 women, there were 464 women (mean [SD] age at baseline, 71.6 [3.5] years) who survived to age 90 years with intact mobility and cognitive functioning, 420 women (mean [SD] age at baseline, 71.3 [3.2] years) who survived to age 90 years without intact mobility and cognitive functioning, and 929 women (mean [SD] age at baseline, 70.2 [3.4] years) who did not survive to age 90 years. Women who survived to age 90 years with intact mobility and cognitive function were healthier at baseline compared with women who survived without those outcomes or who did not survive to age 90 years (eg, 143 women [30.8%] vs 101 women [24.0%] and 202 women [21.7%] with 0 chronic conditions). The odds of surviving to age 90 years with intact mobility were lower for every 1 SD increase in EAA compared with those who did not survive to age 90 years as measured by AgeAccelHorvath (OR, 0.82; 95% CI, 0.69-0.96; P = .01), AgeAccelHannum (OR, 0.67; 95% CI, 0.56-0.80; P < .001), AgeAccelPheno (OR, 0.60; 95% CI, 0.51-0.72; P < .001), and AgeAccelGrim (OR, 0.68; 95% CI, 0.55-0.84; P < .001). ORs were similar for women who survived to age 90 years with intact mobility and cognitive function (eg, AgeAccelHorvath: OR per 1 SD increase in EAA, 0.83; 95% CI, 0.71-0.98; P = .03) compared with women who did not survive to age 90 years.

CONCLUSIONS AND RELEVANCE

These findings suggest that EAA may be a valid biomarker associated with healthy longevity among older women and may be used for risk stratification and risk estimation of future functional and cognitive aging. Outcomes suggest that future studies may focus on the potential for public health interventions to counteract EAA and its association with poor health outcomes to lower disease burden while increasing longevity.

Physiological Systems in Promoting Frailty

Frailty is a complex syndrome affecting a growing sector of the global population as medical developments have advanced human mortality rates across the world. Our current understanding of frailty is derived from studies conducted in the laboratory as well as the clinic, which have generated largely phenotypic information. Far fewer studies have uncovered biological underpinnings driving the onset and progression of frailty, but the stage is set to advance the field with preclinical and clinical assessment tools, multiomics approaches together with physiological and biochemical methodologies. In this article, we provide comprehensive coverage of topics regarding frailty assessment, preclinical models, interventions, and challenges as well as clinical frameworks and prevalence. We also identify central biological mechanisms that may be at play including mitochondrial dysfunction, epigenetic alterations, and oxidative stress that in turn, affect metabolism, stress responses, and endocrine and neuromuscular systems. We review the role of metabolic syndrome, insulin resistance and visceral obesity, focusing on glucose homeostasis, adenosine monophosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), and nicotinamide adenine dinucleotide (NAD+ ) as critical players influencing the age-related loss of health. We further focus on how immunometabolic dysfunction associates with oxidative stress in promoting sarcopenia, a key contributor to slowness, weakness, and fatigue. We explore the biological mechanisms involved in stem cell exhaustion that affect regeneration and may contribute to the frailty-associated decline in resilience and adaptation to stress. Together, an overview of the interplay of aging biology with genetic, lifestyle, and environmental factors that contribute to frailty, as well as potential therapeutic targets to lower risk and slow the progression of ongoing disease is covered. © 2022 American Physiological Society. Compr Physiol 12:1-46, 2022.

Social Justice and Equity: Why Older Adults With Cancer Belong-A Life Course Perspective

The population of older adults with cancer in the United States is rapidly increasing, which will have a substantial impact on the oncology and public health workforces across the cancer continuum, from prevention to end of life. Unfortunately, inequities in existing social structures that cause increased psychosocial stressors have led to disparities in the incidence of cancer and the morbidity and mortality of cancer for individuals from marginalized backgrounds. It is imperative that older adults, especially those from historically marginalized backgrounds, be adequately represented in all stages of cancer research to address health inequities. Continued efforts and progress toward achieving social justice and health equity require a deeper commitment to and better understanding of the impact of social determinants of health within the cancer domain. Undoubtedly, a more holistic and integrated view that extends beyond the biologic and genetic factors of health must be adopted for health entities to recognize the critical role of environmental, behavioral, and social determinants in cancer health disparities. Against this backdrop, this paper uses a life course approach to present a multifactorial framework for understanding and addressing cancer disparities in an effort to advance social justice and health equity for racially and ethnically diverse older adults.

DNA methylation is associated with muscle loss in community-dwelling older men -the Yakumo study- : a preliminary experimental study

Frailty is a state of reduced muscle strength and activity in older people. DNA methylation is associated with osteoporosis and muscle loss in murine and other animal studies, but there are no epidemiological studies in humans. This study aimed to assess the association of osteoporosis and muscle loss with DNA methylation in community-dwelling older people. This cross-sectional study was performed in a rural part of Japan. We analyzed 204 subjects (98 men and 106 women). In univariate analysis, the two groups were compared according to the presence or absence of osteoporosis and of muscle loss. Logistic regression analysis was performed to determine predictors of frailty in the muscle loss group. We used age, sex, body mass index, smoking history, drinking history, serum albumin and C-reactive protein levels, diabetes, hypertension, hyperlipidemia, heart disease history, and LINE-1 DNA methylation as the factors. Probability values < 0.05 were considered to be statistically significant. The levels of LINE-1 DNA methylation in leukocytes were associated with muscle loss in men over the age of 60. LINE-1 DNA methylation levels were not associated with bone mineral density in either the men or women over the age of 60. LINE-1 DNA methylation levels in leukocytes correlated significantly with the risk of frailty in men over the age of 60. Promoting an understanding of DNA methylation may lead to a better understanding of the pathophysiology of muscle loss.

Epigenetic Age Acceleration and Change in Frailty in MOBILIZE Boston

Age-associated changes in DNA methylation have been implicated as 1 mechanism to explain the development of frailty; however, previous cross-sectional studies of epigenetic age acceleration (eAA) and frailty have had inconsistent findings. Few longitudinal studies have considered the association of eAA with change in frailty. We sought to determine the association between eAA and change in frailty in the MOBILIZE Boston cohort. Participants were assessed at 2 visits 12-18 months apart. Intrinsic, extrinsic, GrimAge, and PhenoAge eAA were assessed from whole-blood DNA methylation at baseline using the Infinium 450k array. Frailty was assessed by a continuous frailty score based on the frailty phenotype and by frailty index (FI). Analysis was by correlation and linear regression with adjustment for age, sex, smoking status, and body mass index. Three hundred and ninety-five participants with a frailty score and 431 with an FI had epigenetic and follow-up frailty measures. Mean (standard deviation) ages were 77.8 (5.49) and 77.9 (5.47) for the frailty score and the FI cohorts respectively, and 232 (58.7%) and 257 (59.6%) were female. All participants with epigenetic data identified as White. Baseline frailty score was not correlated with intrinsic or extrinsic eAA, but was correlated with PhenoAge and, even after adjustment for covariates, GrimAge. Baseline FI was correlated with extrinsic, GrimAge, and PhenoAge eAA with and without adjustment. No eAA measure was associated with change in frailty, with or without adjustment. Our results suggest that no eAA measure was associated with change in frailty. Further studies should consider longer periods of follow-up and repeated eAA measurement.

Relationship between five Epigenetic Clocks, Telomere Length and Functional Capacity assessed in Older Adults: Cross-sectional and Longitudinal Analyses

DNA methylation age acceleration (DNAmAA, derived from an epigenetic clock) and relative leukocyte telomere length (rLTL) are widely accepted biomarkers of aging. Nevertheless, it is still unclear which aspects of aging they represent best. Here we evaluated longitudinal associations between baseline rLTL and DNAmAA (estimated with 7-CpG clock) and functional assessments covering different domains of aging. Additionally, we made use of cross-sectional data on these assessments and examined their association with DNAmAA estimated by five different DNAm age measures. Two-wave longitudinal data was available for 1,083 participants of the Berlin Aging Study II (BASE-II) who were re-examined on average 7.4 years after baseline as part of the GendAge study. Functional outcomes were assessed with Fried's frailty score, Tinetti mobility test, falls in the past 12 months (yes/no), Finger-floor distance, Mini Mental State Examination (MMSE), Center for Epidemiologic Studies Depression Scale (CES-D), Activities of Daily Living (ADL), Instrumented ADL (IADL) and Mini Nutritional Assessment (MNA). Overall, we found no evidence for an association between the molecular biomarkers measured at baseline, rLTL and DNAmAA (7-CpG clock), and functional assessments assessed at follow-up. Similarly, a cross-sectional analyses of follow-up data did also not show evidence for associations of the various DNAmAA measures (7-CpG clock, Horvath's clock, Hannum's clock PhenoAge, and GrimAge) with functional assessments. In conclusion, neither rLTL nor 7-CpG DNAmAA were able to predict impairment in the analyzed assessments over a ~7-year time-course. Similarly, DNAmAA estimated from five epigenetic clocks was not a good cross-sectional marker of health deterioration either.

Frailty and pain, human studies and animal models

The hypothesis that pain can predispose to frailty development has been recently investigated in several clinical studies suggesting that frailty and pain may share some mechanisms. Both pain and frailty represent important clinical and social problems and both lack a successful treatment. This circumstance is mainly due to the absence of in-depth knowledge of their pathological mechanisms. Evidence of shared pathways between frailty and pain are preliminary. Indeed, many clinical studies are observational and the impact of pain treatment, and relative pain-relief, on frailty onset and progression has never been investigated. Furthermore, preclinical research on this topic has yet to be performed. Specific researches on the pain-frailty relation are needed. In this narrative review, we will attempt to point out the most relevant findings present in both clinical and preclinical literature on the topic, with particular attention to genetics, epigenetics and inflammation, in order to underline the existing gaps and the potential future interventional strategies. The use of pain and frailty animal models discussed in this review might contribute to research in this area.

Epigenetic Aging Biomarkers Associated With Cognitive Impairment in Older African American Adults With Human Immunodeficiency Virus (HIV)

BACKGROUND

Accelerated epigenetic aging using DNA methylation (DNAm)-based biomarkers has been reported in people with human immunodeficiency virus (HIV, PWH), but limited data are available among African Americans (AA), women, and older PWH.

METHODS

DNAm was measured using Illumina EPIC Arrays for 107 (69 PWH and 38 HIV-seronegative controls) AA adults ≥60 years in New York City. Six DNAm-based biomarkers of aging were estimated: (1) epigenetic age acceleration (EAA), (2) extrinsic epigenetic age acceleration (EEAA), (3) intrinsic epigenetic age acceleration (IEAA), (4) GrimAge, (5) PhenoAge, and (6) DNAm-estimated telomere length (DNAm-TL). The National Institutes of Health (NIH) Toolbox Cognition Battery (domains: executive function, attention, working memory, processing speed, and language) and Montreal Cognitive Assessment (MoCA) were administered. Participants were assessed for frailty by the Fried criteria.

RESULTS

The PWH and control groups did not differ by sex, chronological age, or ethnicity. In total, 83% of PWH had a viral load <50 copies/mL, and 94% had a recent CD4 ≥200 cells/µL. The PWH group had a higher EAA, EEAA, GrimAge, and PhenoAge, and a lower DNAm-TL compared to the controls. IEAA was not different between groups. For PWH, there were significant negative correlations between IEAA and executive function, attention, and working memory and PhenoAge and attention. No associations between biomarkers and frailty were detected.

CONCLUSIONS

Evidence of epigenetic age acceleration was observed in AA older PWH using DNAm-based biomarkers of aging. There was no evidence of age acceleration independent of cell type National Institutes of Health composition (IEAA) associated with HIV, but this measure was associated with decreased cognitive function among PWH.

Cardiovascular health is associated with the epigenetic clock in the Berlin Aging Study II (BASE-II)

The epigenetic clock parameter DNAm age acceleration is a promising biomarker of aging. We have recently described an epigenetic clock based on only seven cytosine-phosphate-guanine sites, which is highly associated with chronological age. The aim of this study was to examine this epigenetic clock with respect to its relationship with cardiovascular health (CVH) in older adults. We used data from the Berlin Aging Study II (BASE-II; 1,671 participants; 68.8 ± 3.7 years old). CVH was operationalized using two different CVH scores, the Framingham Risk Score (FRS), and the Life's simple 7 (LS7). To adjust for potential confounding, e.g. by sex, we performed regression analyses. The LS7 score was higher, i.e. more favorable, in woman than in men (8.8 ± 2 vs. 8.2 ± 2, p < 0.001). DNAm age acceleration was associated with the FRS (β = 0.122, p = 0.028) and with the LS7 (β = -0.804, p = 0.032). In more detail, physical activity (β = -0.461, p = 0.05), HDL-cholesterol (β = 0.343, p = 0.03) and total cholesterol (β = -0.364, p = 0.002) were associated with epigenetic age acceleration. We present evidence suggesting that better CVH is associated with decelerated biological aging measured by the epigenetic clock.

Comparative validation of three DNA methylation algorithms of ageing and a frailty index in relation to mortality: results from the ESTHER cohort study

Background

Three DNA methylation (DNAm) based algorithms, DNAm PhenoAge acceleration (AgeAccelPheno), DNAm GrimAge acceleration (AgeAccelGrim), and mortality risk score (MRscore), based on methylation in 513, 1030, and 10 CpGs, respectively, were established to predict health outcomes and mortality. We aimed to compare and validate the predictive ability of these scores and frailty in relation to mortality in a population-based cohort from Germany.

Methods

DNA methylation in whole blood was measured by the Infinium Methylation EPIC BeadChip kit (EPIC, Illumina, San Diego, CA, USA) in two random subsets of the ESTHER cohort study (n = 741 and n = 1030). AgeAccelPheno, AgeAccelGrim, and a revised MRscore to adapt EPIC, the MRscore with 8 CpGs (MRscore-8CpGs), were calculated. Frailty was assessed by a frailty index (FI).

Findings

During 17 years of follow-up, 458 deaths were observed. All DNAm algorithms and FI were positively correlated with each other. AgeAccelPheno, AgeAccelGrim, MRscore, and FI showed independent associations with all-cause mortality [hazard ratio (95% CI) per SD increase = 1·32 (1·19-1·46), 1·47 (1·32-1·64), 1·73 (1·49-2·01), and 1·31 (1·20-1·43), respectively]. Harrell's C-statistic was 0·710 for a model predicting mortality by age, sex, and leukocyte composition and increased to 0·759 in a model including MRscore-8CpGs and FI. The predictive performance was further improved (Harrell's C-statistic = 0·766) when additionally including AgeAccelPheno and AgeAccelGrim into the model.

Interpretation

The combination of a DNA methylation score based on 8 CpGs only and an easy to ascertain frailty index may strongly enhance mortality prediction beyond age and sex.

Funding

The ESTHER study was funded by grants from the Baden-Württemberg state Ministry of Science, Research and Arts (Stuttgart, Germany), the Federal Ministry of Education and Research (Berlin, Germany), the Federal Ministry of Family Affairs, Senior Citizens, Women and Youth (Berlin, Germany), and the Saarland State Ministry of Health, Social Affairs, Women and the Family (Saarbrücken, Germany). The work of Xiangwei Li was supported by a grant from Fondazione Cariplo (Bando Ricerca Malattie invecchiamento, #2017-0653).

Frailty in Lung Transplantation: Candidate Assessment and Optimization

The concept of frailty has gained considerable interest in clinical solid-organ transplantation over the past decade. Frailty as a phenotypic construct to describe a patient's risk from biologic stresses has an impact on posttransplant survival. There is keen interest in characterizing frailty in lung transplantation, both to determine which patients are suitable candidates for listing and also to prepare for their care in the aftermath of lung transplantation. Here, we review the current status of research on frailty in lung transplant candidates and recipients. This review will highlight areas of uncertainty for frailty in clinical lung transplantation that are likely to impact the state-of-the-art in the field for the next decade.

Epigenetic age is associated with baseline and 3-year change in frailty in the Canadian Longitudinal Study on Aging

BACKGROUND

The trajectory of frailty in older adults is important to public health; therefore, markers that may help predict this and other important outcomes could be beneficial. Epigenetic clocks have been developed and are associated with various health-related outcomes and sociodemographic factors, but associations with frailty are poorly described. Further, it is uncertain whether newer generations of epigenetic clocks, trained on variables other than chronological age, would be more strongly associated with frailty than earlier developed clocks. Using data from the Canadian Longitudinal Study on Aging (CLSA), we tested the hypothesis that clocks trained on phenotypic markers of health or mortality (i.e., Dunedin PoAm, GrimAge, PhenoAge and Zhang in Nat Commun 8:14617, 2017) would best predict changes in a 76-item frailty index (FI) over a 3-year interval, as compared to clocks trained on chronological age (i.e., Hannum in Mol Cell 49:359-367, 2013, Horvath in Genome Biol 14:R115, 2013, Lin in Aging 8:394-401, 2016, and Yang Genome Biol 17:205, 2016).

RESULTS

We show that in 1446 participants, phenotype/mortality-trained clocks outperformed age-trained clocks with regard to the association with baseline frailty (mean = 0.141, SD = 0.075), the greatest of which is GrimAge, where a 1-SD increase in ΔGrimAge (i.e., the difference from chronological age) was associated with a 0.020 increase in frailty (95% CI 0.016, 0.024), or ~ 27% relative to the SD in frailty. Only GrimAge and Hannum (Mol Cell 49:359-367, 2013) were significantly associated with change in frailty over time, where a 1-SD increase in ΔGrimAge and ΔHannum 2013 was associated with a 0.0030 (95% CI 0.0007, 0.0050) and 0.0028 (95% CI 0.0007, 0.0050) increase over 3 years, respectively, or ~ 7% relative to the SD in frailty change.

CONCLUSION

Both prevalence and change in frailty are associated with increased epigenetic age. However, not all clocks are equally sensitive to these outcomes and depend on their underlying relationship with chronological age, healthspan and lifespan. Certain clocks were significantly associated with relatively short-term changes in frailty, thereby supporting their utility in initiatives and interventions to promote healthy aging.

Intrinsic Capacity: Validation of a New WHO Concept for Healthy Ageing in a Longitudinal Chinese Study

BACKGROUND

The World Health Organization has proposed a model of healthy aging built around the concept of functional ability, comprising an individual's intrinsic capacity, the physical and social environment they occupy, and interactions between the two. However, these constructs have been poorly defined. We examined the structure of intrinsic capacity in a representative sample of the Chinese population aged 60 years and over and assessed its value in predicting declining performance in instrumental activities of daily living (IADLs) and activities of daily living (ADLs) using similar methods to a construct validation previously undertaken in an English cohort.

METHODS

De-identified data were accessed on 7643 participants of the China Health and Retirement Longitudinal Study (CHARLS) 2011 and 2013 waves. Incrementally related structural equation modelling was applied, including exploratory and confirmatory factor analysis, and path analysis. Multiple linear regression tested construct validity, and simple and serial mediation models assessed predictive validity.

RESULTS

Factor loadings for the models showed a clear structure for intrinsic capacity: one general factor with five subfactors - locomotor, cognitive, psychological and sensory capacities, and vitality (reflecting underlying physiologic changes). Intrinsic capacity predicted declining performance in both IADLs (Standardized Coefficient (SE) -0.324 (0.02), p<0.001) and ADLs (-0.227 (0.03), p<0.001), after accounting for age, sex, education, wealth and number of chronic diseases. Each characteristic was associated with intrinsic capacity, providing strong construct validity.

CONCLUSIONS

Assessment of intrinsic capacity provides valuable information on an individual's subsequent functioning beyond that afforded by age, other personal factors and multimorbidity.

No association between frailty index and epigenetic clocks in Italian semi-supercentenarians

Centenarians experience successful ageing, although they still present high heterogeneity in their health status. The frailty index is a biomarker of biological age, able to capture such heterogeneity, even at extreme old age. At the same time, other biomarkers (e.g., epigenetic clocks) may be informative the biological age of the individual and potentially describe the ageing status in centenarians. In this article, we explore the relationship between epigenetic clocks and frailty index in a cohort of Italian centenarians. No association was reported, suggesting that these two approaches may describe different aspects of the same ageing process.

Implementing Precision Medicine in Human Frailty through Epigenetic Biomarkers

The main epigenetic features in aging are: reduced bulk levels of core histones, altered pattern of histone post-translational modifications, changes in the pattern of DNA methylation, replacement of canonical histones with histone variants, and altered expression of non-coding RNA. The identification of epigenetic mechanisms may contribute to the early detection of age-associated subclinical changes or deficits at the molecular and/or cellular level, to predict the development of frailty, or even more interestingly, to improve health trajectories in older adults. Frailty reflects a state of increased vulnerability to stressors as a result of decreased physiologic reserves, and even dysregulation of multiple physiologic systems leading to adverse health outcomes for individuals of the same chronological age. A key approach to overcome the challenges of frailty is the development of biomarkers to improve early diagnostic accuracy and to predict trajectories in older individuals. The identification of epigenetic biomarkers of frailty could provide important support for the clinical diagnosis of frailty, or more specifically, to the evaluation of its associated risks. Interventional studies aimed at delaying the onset of frailty and the functional alterations associated with it, would also undoubtedly benefit from the identification of frailty biomarkers. Specific to the article yet reasonably common within the subject discipline.

A Systematic Review and Meta-analysis of Environmental, Lifestyle, and Health Factors Associated With DNA Methylation Age

DNA methylation (DNAm) algorithms of biological age provide a robust estimate of an individual's chronological age and can predict their risk of age-related disease and mortality. This study reviewed the evidence that environmental, lifestyle and health factors are associated with the Horvath and Hannum epigenetic clocks. A systematic search identified 61 studies. Chronological age was correlated with DNAm age in blood (median .83, range .13-.99). In a meta-analysis body mass index (BMI) was associated with increased DNAm age (Hannum β: 0.07, 95% CI 0.04 to 0.10; Horvath β: 0.06, 95% CI 0.02 to 0.10), but there was no association with smoking (Hannum β: 0.12, 95% CI -0.50 to 0.73; Horvath β:0.18, 95% CI -0.10 to 0.46). DNAm age was positively associated with frailty (three studies, n = 3,093), and education was negatively associated with the Hannum estimate of DNAm age specifically (four studies, n = 13,955). For most other exposures, findings were too inconsistent to draw conclusions. In conclusion, BMI was positively associated with biological aging measured using DNAm, with some evidence that frailty also increased aging. More research is needed to provide conclusive evidence regarding other exposures. This field of research has the potential to provide further insights into how to promote slower biological aging and ultimately prolong healthy life.

The use of DNA methylation clock in aging research

One of the key characteristics of aging is a progressive loss of physiological integrity, which weakens bodily functions and increases the risk of death. A robust biomarker is important for the assessment of biological age, the rate of aging, and a person's health status. DNA methylation clocks, novel biomarkers of aging, are composed of a group of cytosine-phosphate-guanine dinucleotides, the DNA methylation status of which can be used to accurately measure subjective age. These clocks are considered accurate biomarkers of chronological age for humans and other vertebrates. Numerous studies have demonstrated these clocks to quantify the rate of biological aging and the effects of longevity and anti-aging interventions. In this review, we describe the purpose and use of DNA methylation clocks in aging research.

Omics biomarkers for frailty in older adults

Frailty is a clinical state characterized by an age-related unsteady state of the body, a decline in physiological function, and an increased vulnerability to adverse outcomes. Early diagnosis of frailty is important for improving the quality of life in older adults and promoting healthy aging. The biological mechanisms underlying frailty have been extensively studied in recent years. Combining assessment tools and biomarkers can facilitate the early diagnosis of frailty. However, there is a lack of stable and reliable frailty-related biomarkers for use in clinical practice. Advances in the multi-omics platforms have provided new information on the molecular mechanisms underlying frailty. Thus, identifying biomarkers using omics-based approaches helps explore the physiological mechanisms underlying frailty, and aids the evaluation of the risk of frailty development and progression. This article reviews the current status of frailty biomarkers from the genomics, transcriptomics, proteomics, and metabolomics perspectives.

Frailty and cognitive decline

Frailty and cognitive impairment are among the 2 most common geriatric syndromes. Their presence poses major risks to the elderly including greater disability, reduced quality of life, and higher morbi-mortality. Recent evidence suggest that frailty can be a risk factor for incident dementia. The opposite is also true since subjects with Alzheimer's disease and other dementia also present with more severe frailty measures. The mechanisms for the association between frailty and cognitive impairment is not clear, but possibly involves abnormalities in biological processes related to aging. Here, we will review the current evidence of the association between frailty and cognitive impairment. We will also review the possible biological mechanistic links between the 2 conditions. Finally, we will address potential therapeutic targets and interventions that can mitigate both conditions.

The environment as a determinant of successful aging or frailty

The number of elderly persons is rising rapidly, and healthspan is a key factor in determining the well-being of individuals and the sustainability of national health systems. Environmental health is crucial for a "successful aging". Complex relationships between environmental factors and non-communicable diseases play a major role, causing or accelerating disabilities. Besides genetic factors, aging results from the concurrence of several environmental factors starting from early (i.e. in utero) life, able to increase susceptibility to diseases in adulthood, and to promote frailty in the elderly. In aged people, an unhealthy environment contributes to a fast and early decline and increases vulnerability. Exposure to pollutants facilitates the onset and progression of cardiovascular, respiratory, metabolic and neurologic diseases through direct effects and epigenetic mechanisms negatively affecting biological age. Healthy diet, healthy environment and constant physical activity could counteract, at least in part, the negative effects of environmental stressors. Almost all environmental factors generating detrimental effects on aging are modifiable, with relevant implications in terms of primary prevention measures potentially leading to decreased frailty, to an increase in the number of years lived without diseases or disability, and to a significant reduction in health expenditure.

One-year Mediterranean diet promotes epigenetic rejuvenation with country- and sex-specific effects: a pilot study from the NU-AGE project

Mediterranean diet has been proposed to promote healthy aging, but its effects on aging biomarkers have been poorly investigated. We evaluated the impact of a 1-year Mediterranean-like diet in a pilot study including 120 elderly healthy subjects from the NU-AGE study (60 Italians, 60 Poles) by measuring the changes in their epigenetic age, assessed by Horvath's clock. We observed a trend towards epigenetic rejuvenation of participants after nutritional intervention. The effect was statistically significant in the group of Polish females and in subjects who were epigenetically older at baseline. A genome-wide association study of epigenetic age changes after the intervention did not return significant (adjusted p value < 0.05) loci. However, we identified small-effect alleles (nominal p value < 10-4), mapping in genes enriched in pathways related to energy metabolism, regulation of cell cycle, and of immune functions. Together, these findings suggest that Mediterranean diet can promote epigenetic rejuvenation but with country-, sex-, and individual-specific effects, thus highlighting the need for a personalized approach to nutritional interventions.

Age-Related DNA Methylation Changes: Potential Impact on Skeletal Muscle Aging in Humans

Human aging is accompanied by a decline in muscle mass and muscle function, which is commonly referred to as sarcopenia. Sarcopenia is associated with detrimental clinical outcomes, such as a reduced quality of life, frailty, an increased risk of falls, fractures, hospitalization, and mortality. The exact underlying mechanisms of sarcopenia are poorly delineated and the molecular mechanisms driving the development and progression of this disorder remain to be uncovered. Previous studies have described age-related differences in gene expression, with one study identifying an age-specific expression signature of sarcopenia, but little is known about the influence of epigenetics, and specially of DNA methylation, in its pathogenesis. In this review, we will focus on the available knowledge in literature on the characterization of DNA methylation profiles during skeletal muscle aging and the possible impact of physical activity and nutrition. We will consider the possible use of the recently developed DNA methylation-based biomarkers of aging called epigenetic clocks in the assessment of physical performance in older individuals. Finally, we will discuss limitations and future directions of this field.

Frailty biomarkers in humans and rodents: Current approaches and future advances

Even though they would have great benefit across research and clinical fields, currently there are no accepted biomarkers of frailty. Cross-sectional studies in humans have identified promising candidates including inflammatory markers such as IL-6, immune markers such as WBC count, clinical markers such as albumin, endocrine markers such as vitamin D, oxidative stress markers such as isoprostanes, proteins such as BDNF and epigenetic markers such as DNA methylation, but there are limitations to the current state of the research. Future approaches to the identification of frailty biomarkers should include longitudinal studies, studies using animal models of frailty, studies incorporating novel biomarkers combined into composite panels, and studies investigating sex differences and potential overlap between markers of biological age and frailty.

The Impact of Caloric Restriction on the Epigenetic Signatures of Aging

Aging is characterized by an extensive remodeling of epigenetic patterns, which has been implicated in the physiopathology of age-related diseases. Nutrition plays a significant role in modulating the epigenome, and a growing amount of data indicate that dietary changes can modify the epigenetic marks associated with aging. In this review, we will assess the current advances in the relationship between caloric restriction, a proven anti-aging intervention, and epigenetic signatures of aging. We will specifically discuss the impact of caloric restriction on epigenetic regulation and how some of the favorable effects of caloric restriction on lifespan and healthspan could be mediated by epigenetic modifications.

The epigenetic clock as a predictor of disease and mortality risk: a systematic review and meta-analysis

BACKGROUND

Ageing is one of the principal risk factors for many chronic diseases. However, there is considerable between-person variation in the rate of ageing and individual differences in their susceptibility to disease and death. Epigenetic mechanisms may play a role in human ageing, and DNA methylation age biomarkers may be good predictors of age-related diseases and mortality risk. The aims of this systematic review were to identify and synthesise the evidence for an association between peripherally measured DNA methylation age and longevity, age-related disease, and mortality risk.

METHODS

A systematic search was conducted in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Using relevant search terms, MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and PsychINFO databases were searched to identify articles meeting the inclusion criteria. Studies were assessed for bias using Joanna Briggs Institute critical appraisal checklists. Data was extracted from studies measuring age acceleration as a predictor of age-related diseases, mortality or longevity, and the findings for similar outcomes compared. Using Review Manager 5.3 software, two meta-analyses (one per epigenetic clock) were conducted on studies measuring all-cause mortality.

RESULTS

Twenty-three relevant articles were identified, including a total of 41,607 participants. Four studies focused on ageing and longevity, 11 on age-related disease (cancer, cardiovascular disease, and dementia), and 11 on mortality. There was some, although inconsistent, evidence for an association between increased DNA methylation age and risk of disease. Meta-analyses indicated that each 5-year increase in DNA methylation age was associated an 8 to 15% increased risk of mortality.

CONCLUSION

Due to the small number of studies and heterogeneity in study design and outcomes, the association between DNA methylation age and age-related disease and longevity is inconclusive. Increased epigenetic age was associated with mortality risk, but positive publication bias needs to be considered. Further research is needed to determine the extent to which DNA methylation age can be used as a clinical biomarker.

Extracellular Spermine Activates DNA Methyltransferase 3A and 3B

We first demonstrated that long-term increased polyamine (spermine, spermidine, putrescine) intake elevated blood spermine levels in mice and humans, and lifelong consumption of polyamine-rich chow inhibited aging-associated increase in aberrant DNA methylation, inhibited aging-associated pathological changes, and extend lifespan of mouse. Because gene methylation status is closely associated with aging-associated conditions and polyamine metabolism is closely associated with regulation of gene methylation, we investigated the effects of extracellular spermine supplementation on substrate concentrations and enzyme activities involved in gene methylation. Jurkat cells and human mammary epithelial cells were cultured with spermine and/or D,L-alpha-difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase. Spermine supplementation inhibited enzymatic activities of adenosylmethionine decarboxylase in both cells. The ratio of decarboxylated S-adenosylmethionine to S-adenosyl-L-methionine increased by DFMO and decreased by spermine. In Jurkat cells cultured with DFMO, the protein levels of DNA methyltransferases (DNMTs) 1, 3A and 3B were not changed, however the activity of the three enzymes markedly decreased. The protein levels of these enzymes were not changed by addition of spermine, DNMT 3A and especially 3B were activated. We show that changes in polyamine metabolism dramatically affect substrate concentrations and activities of enzymes involved in gene methylation.

The biology of frailty in humans and animals: Understanding frailty and promoting translation

Frailty is a state of high vulnerability to adverse health outcomes. This concept is used to explain the heterogeneity in rates of aging in people of the same age. Frailty has important clinical implications, because even minor stressors can lead to adverse outcomes, including death, in frail individuals. Although frailty mechanisms are not well understood, advances in our ability to qualify frailty have encouraged efforts in this area. Quantification of frailty with both "frailty phenotype" and "frailty index" approaches has begun to highlight putative frailty mechanisms and new animal models of frailty are inspiring preclinical research. These models either adapt frailty phenotype and frailty index tools for use in animals or they use genetically manipulated mice that mimic conditions seen in frailty (eg, inflammation, sarcopenia, weakness). This review: describes commonly used tools to quantify frailty clinically, discusses potential frailty mechanisms, and describes animal models of frailty. It also highlights how these models have been used to explore frailty mechanisms and potential frailty interventions, including pharmacological treatments, diet, and exercise. These exciting new developments in the field have the potential to facilitate translational research, improve our understanding of mechanisms of frailty, and help develop new interventions to mitigate frailty in our aging population.

Mini Nutritional Assessment Scores Indicate Higher Risk for Prospective Mortality and Contrasting Correlation With Age-Related Epigenetic Biomarkers

The plasticity of the individual epigenetic landscape that goes to countless rearrangements throughout life is closely the reflection of environmental factors such as chemical exposure, socio-economic status and nutrient intakes both early and late in life. The Mini Nutritional Assessment (MNA) is a well-validated tool for assessing malnutrition in old people. It includes 6 (MNA-SF) or 18 (MNA-LF) self-reported questions derived from general, anthropometric, dietary, and self- assessment. We evaluated the association between the nutritional status, as measured by MNA, and methylation biomarkers we previously demonstrated to be associated with chronological and biological age in human. We found that malnutrition is positively correlated with DNA methylation status at the global level, in line with our previous reports. On the contrary, most of the sites located within specific genes, which were previously reported to be correlated with chronological and biological aging, showed to be not affected by malnutrition, or even to have correlations with malnutrition opposite to those previously reported with frailty. These results may suggest that malnutrition is among the first effects of disability and other age- related problems and a generalized non-specific epigenetic remodeling may be the initial response of the organism. By contrast, the fine remodeling of specific genomic sites is scarcely affected by malnutrition and may respond to a more complex interaction of different factors. Therefore, although malnutrition in the elderly is certainly a risk factor for survival, this is partially independent of the aging process of the organism which leads to the methylation remodeling previously described to measure chronological and biological aging.

Fifteen years of progress in understanding frailty and health in aging

The notion of frailty has evolved for more than 15 years. Although there is no consensus definition, frailty reflects a state of increased vulnerability to adverse health outcomes for individuals of the same chronological age. Two commonly used clinical tools, the frailty index and the frailty phenotype, both measure health-related deficits. The frailty index is a ratio of the number of deficits that an individual has accumulated divided by all deficits measured, whereas the phenotype specifies frailty as represented by poor performance in three of five criteria (i.e., weight loss, exhaustion, weakness, slowness, lack of activity). From human studies, animal models of both approaches have been developed and are beginning to shed light on mechanisms underlying frailty, the influence of frailty on disease expression, and new interventions to attenuate frailty. Currently, back-translation to humans is occurring. As we start to understand subcellular mechanisms involved in damage and repair as well as their response to treatment, we will begin to understand the molecular basis of aging and, thus, of frailty.

Polyamine Metabolism and Gene Methylation in Conjunction with One-Carbon Metabolism

Recent investigations have revealed that changes in DNA methylation status play an important role in aging-associated pathologies and lifespan. The methylation of DNA is regulated by DNA methyltransferases (DNMT1, DNMT3a, and DNMT3b) in the presence of S-adenosylmethionine (SAM), which serves as a methyl group donor. Increased availability of SAM enhances DNMT activity, while its metabolites, S-adenosyl-l-homocysteine (SAH) and decarboxylated S-adenosylmethionine (dcSAM), act to inhibit DNMT activity. SAH, which is converted from SAM by adding a methyl group to cytosine residues in DNA, is an intermediate precursor of homocysteine. dcSAM, converted from SAM by the enzymatic activity of adenosylmethionine decarboxylase, provides an aminopropyl group to synthesize the polyamines spermine and spermidine. Increased homocysteine levels are a significant risk factor for the development of a wide range of conditions, including cardiovascular diseases. However, successful homocysteine-lowering treatment by vitamins (B6, B12, and folate) failed to improve these conditions. Long-term increased polyamine intake elevated blood spermine levels and inhibited aging-associated pathologies in mice and humans. Spermine reversed changes (increased dcSAM, decreased DNMT activity, aberrant DNA methylation, and proinflammatory status) induced by the inhibition of ornithine decarboxylase. The relation between polyamine metabolism, one-carbon metabolism, DNA methylation, and the biological mechanism of spermine-induced lifespan extension is discussed.