Telomeres and frailty

Frailty

Frailty is an emerging geriatric syndrome that refers to a state of increased vulnerability to adverse events including mortality, morbidity, disability, hospitalization, and nursing home admission. Despite its long conceptual and operational history in research and publications, frailty and mechanisms of frailty development are still poorly understood. In this review, we describe a number of conceptual models—reliability, allostatic load, and complexity—that have been put forward to explain the dynamic nature of frailty. We illustrate a consolidated pathophysiological model of frailty, taking into consideration the large and exponentially growing body of studies regarding predictors, indicators, and outcomes of frailty. The model addresses cellular (e.g., oxidative damage and telomere length) and systemic mechanisms (e.g., endocrinal, inflammatory, coagulatory, and metabolic deficiencies) of frailty, moderating or risk factors (e.g., ethnicity, lifestyle, and comorbidities), and outcomes (morbidity, disability, and cognitive decline). Finally, we identify the weaknesses of traditional epidemiological approaches for studying complex phenomena related to frailty and propose areas for future methodological and physiological inquiry.

Frailty in Patients with Cardiovascular Disease: Why, When, and How to Measure

Frailty is a geriatric syndrome of impaired resistance to stressors due to a decline in physiologic reserve. Frailty and cardiovascular disease (CVD) share a common biological pathway, and CVD may accelerate the development of frailty. Frailty is identified in 25% to 50% of patients with CVD, depending on the frailty scale used and the population studied. Frail patients with CVD, especially those undergoing invasive procedures or suffering from coronary artery disease and heart failure, are more likely to suffer adverse outcomes as compared to their non-frail counterparts. Five-meter gait speed is a simple and effective way of objectively measuring frailty in patients with CVD and should be incorporated in risk assessment.

Healthy aging and disease: role for telomere biology?

Aging is a biological process that affects most cells, organisms and species. Human aging is associated with increased susceptibility to a variety of chronic diseases, including cardiovascular disease, Type 2 diabetes, neurological diseases and cancer. Despite the remarkable progress made during the last two decades, our understanding of the biology of aging remains incomplete. Telomere biology has recently emerged as an important player in the aging and disease process.

Sex differences in sand lizard telomere inheritance: paternal epigenetic effects increases telomere heritability and offspring survival

Background

To date, the only estimate of the heritability of telomere length in wild populations comes from humans. Thus, there is a need for analysis of natural populations with respect to how telomeres evolve.

Methodology/Principal Findings

Here, we show that telomere length is heritable in free-ranging sand lizards, Lacerta agilis. More importantly, heritability estimates analysed within, and contrasted between, the sexes are markedly different; son-sire heritability is much higher relative to daughter-dam heritability. We assess the effect of paternal age on Telomere Length (TL) and show that in this species, paternal age at conception is the best predictor of TL in sons. Neither paternal age per se at blood sampling for telomere screening, nor corresponding age in sons impact TL in sons. Processes maintaining telomere length are also associated with negative fitness effects, most notably by increasing the risk of cancer and show variation across different categories of individuals (e.g. males vs. females). We therefore tested whether TL influences offspring survival in their first year of life. Indeed such effects were present and independent of sex-biased offspring mortality and offspring malformations.

Conclusions/Significance

TL show differences in sex-specific heritability with implications for differences between the sexes with respect to ongoing telomere selection. Paternal age influences the length of telomeres in sons and longer telomeres enhance offspring survival.

Sexual differences in telomere selection in the wild

Telomere length is restored primarily through the action of the reverse transcriptase telomerase, which may contribute to a prolonged lifespan in some but not all species and may result in longer telomeres in one sex than the other. To what extent this is an effect of proximate mechanisms (e.g. higher stress in males, higher oestradiol/oestrogen levels in females), or is an evolved adaptation (stronger selection for telomere length in one sex), usually remains unknown. Sand lizard (Lacerta agilis) females have longer telomeres than males and better maintain telomere length through life than males do. We also show that telomere length more strongly contributes to life span and lifetime reproductive success in females than males and that telomere length is under sexually diversifying selection in the wild. Finally, we performed a selection analysis with number of recruited offspring into the adult population as a response variable with telomere length, life span and body size as predictor variables. This showed significant differences in selection pressures between the sexes with strong ongoing selection in females, with these three predictors explaining 63% of the variation in recruitment. Thus, the sexually dimorphic telomere dynamics with longer telomeres in females is a result of past and ongoing selection in sand lizards. Finally, we compared the results from our selection analyses based on Telometric-derived data to the results based on data generated by the software ImageJ. ImageJ resulted in shorter average telomere length, but this difference had virtually no qualitative effect on the patterns of ongoing selection.

Frailty defined by deficit accumulation and geriatric medicine defined by frailty

As nonreplicative cells age, they commonly accumulate subcellular deficits that can compromise function. As people age, they too experience problems that can accumulate. As deficits (symptoms, signs, illnesses, disabilities) accumulate, people become more susceptible to adverse health outcomes, including worse health and even death. This state of increased risk of adverse health outcomes is indistinguishable from the idea of frailty, so deficit accumulation represents another way to define frailty. Counting deficits not only allows grades of frailty to be discerned but also provides insights into the complex problems of older adults. This process is potentially useful to geriatricians who need to be experts in managing complexity. A key to managing complexity is through instruments such as a comprehensive geriatric assessment, which can serve as the basis for routine clinical estimation of an individual's degree of frailty. Understanding people and their needs as deficits accumulate is an exciting challenge for clinical research on frailty and its management by geriatricians.

Fatigue in older adults: an early indicator of the aging process?

The aim of this paper is to give an overview of research on fatigue in older adults, with a focus on fatigue as an early indicator of the aging process. Fatigue is a strong predictor of functional limitations, disability, mortality, and other adverse outcomes in young-old and old-old populations, between men and women, and in different geographic localities. Several biological, physiological and social explanations are proposed: fatigue may be seen not only as a self-reported indicator of frailty, defined as a physiologic state of increased vulnerability to stressors, which results from decreased physiologic reserves and even dysregulation of multiple physiologic systems, but also this state may be accelerated because of the cumulative impact of social, mental and biological factors throughout life.

The effect of telomere length, a marker of biological aging, on bone mineral density in elderly population

Telomere length (TL), as a reflection of aging and inflammatory processes, may be associated with bone mineral density (BMD). This study examines the association between TL and BMD cross-sectionally and the rate of bone loss over a 4-year period in 1,867 Chinese elderly community living subjects. After adjusting for confounding factors, no association was observed with BMD or bone loss. The decline in BMD with aging is not reflected by corresponding changes in telomere length.

INTRODUCTION

Bone mineral density (BMD) is influenced by the dynamics of aging, inflammatory, and bone remodeling processes. Telomere length (TL) is a reflection of the former two processes and may also be associated with bone loss.

METHODS

Hip BMD was measured in 1,867 Chinese elderly community living subjects and the relationship between leukocyte TL measured using quantitative real-time polymerase chain reaction, and bone loss after 4 years was examined.

RESULTS

Women had greater bone loss than men. In women, age of menopause, menarche, estrogen treatment/replacement therapy, and history of previous fracture were also among the significant covariates. However, in multivariate analyses, TL was not associated with BMD in either sex.

CONCLUSIONS

TL was not associated with either baseline BMD or bone loss over 4 years and accounted for less than 1.6% of the baseline BMD.

Dynamics and heterogeneity in the process of human frailty and aging: evidence from the U.S. older adult population

OBJECTIVES

This study investigated the dynamics and heterogeneity of the frailty index (FI) conceived as a systemic indicator of biological aging in the community-dwelling older adult population in the United States.

METHODS

We used panel data on multiple birth cohorts from the Health and Retirement Survey 1993-2006 and growth curve models to estimate age trajectories of the FI and their differences by sex, race, and socioeconomic status (SES) within cohorts.

RESULTS

The FI for cohorts born before 1942 exhibit quadratic increases with age and accelerated increases in the accumulation of health deficits. More recent cohorts exhibit higher average levels of and rates of increment in the FI than their predecessors do at the same ages. Females, non-Whites, and individuals with low education and income exhibit greater degrees of physiological deregulation than their male, White, and high-SES counterparts at any age. Patterns of sex, race, and SES differentials in rates of aging vary across cohorts.

DISCUSSION

Adjusting for social behavioral factors, the analysis provides evidence for physiological differences in the aging process among recent cohorts of older adults, points to the need for biological explanations of female excess in general system damage, and reveals the insufficiency of any single mechanism for depicting the racial and SES differences in the process of physiological deterioration.

Older men with higher self-rated socioeconomic status have shorter telomeres

BACKGROUND

previous studies examining the relationship between socioeconomic status and telomere length showed conflicting results, one study finding shorter telomere length in subjects with lower socioeconomic status and one showing no relationship.

DESIGN

cross-sectional study.

SETTING

community-living elderly Chinese in Hong Kong.

OBJECTIVE

this study examines the relationship between self-rated social economic status and telomere length in Hong Kong Chinese men and women aged 65 years and over living in the community.

SUBJECTS AND METHOD

information was collected from 958 men and 978 women regarding possible confounding factors such as the presence of chronic diseases, smoking, physical activity level, dietary intake and body mass index. Telomere length was measured by quantitative PCR.

RESULT

in men only, after adjustment for age and other confounding factors, a higher ranking in community standing was associated with shorter telomere length.

CONCLUSION

men with higher self-rated socioeconomic status have shorter telomeres, possibly mediated through psychosocial rather than lifestyle factors or the presence of chronic disease. There may be cultural ethnic and age-related differences in social determinants of health.

Reconstructive urology and geriatrics: issues in older adults

PURPOSE OF REVIEW

The elderly population is continuing to expand at record pace in the vast majority of countries worldwide. Many urologic conditions that necessitate reconstructive surgery occur in geriatric patients. To date, there has been a paucity of research on the effects of aging with regard to reconstructive procedures in elderly patients. This review examines factors that influence the feasibility and outcomes of reconstructive urologic surgery in older adults.

RECENT FINDINGS

Age alone has generally not been identified as a significant predictive factor for outcomes in geriatric patients undergoing surgery. Comorbid diseases associated with reduction of physiologic reserve capacity and impairments in the level of independence for activities of daily living appear to have more predictive value. Recent research has focused on defining frailty as a condition that frequently occurs in older adults and may influence clinical outcomes. A variety of cellular and tissue changes associated with aging have also been studied. Inflammatory mediators may play an important role in this process.

SUMMARY

Many urologic conditions that require reconstructive surgery occur in elderly patients. Careful planning may help to improve outcomes. However, there appear to be inherent changes associated with the physiology of normal aging that can significantly influence this process.

Chinese tea consumption is associated with longer telomere length in elderly Chinese men

Environmental and lifestyle factors that affect oxidative stress and inflammation may influence telomere length (TL). There are limited data to relate the effect of dietary components on TL. The present study examined the association between food groups and TL in a sample of elderly Chinese. In a sample of 2006 Chinese (976 men and 1030 women) aged 65 years and over, TL was measured by quantitative real-time PCR and daily intake of food groups was assessed by a validated FFQ. Linear regression and analysis of covariance were used to examine the association between food group intake and TL, with adjustment for demographic and lifestyle factors. In men, only Chinese tea consumption was significantly associated with TL after adjustment for demographics and lifestyle factors (P = 0·002). Mean difference in TL for those in the highest quartile of Chinese tea consumption (>3 cups/d or >750 ml/d) as compared with those in the lowest quartile of Chinese tea consumption ( ≤ 0·28 cups/d or ≤ 70 ml/d) was 0·46 kb, corresponding to approximately a difference of 5 years of life. In women, intake of fats and oils was borderline and negatively associated with TL after adjustment for demographic and lifestyle factors (P = 0·037). In conclusion, Chinese tea consumption was positively associated with TL in elderly Chinese men.