Assessment of candidate ocular biomarkers of ageing in a South African adult population: relationship with chronological age and systemic biomarkers

Genetically predicted frailty index and risk of stroke and Alzheimer's disease

BACKGROUND AND PURPOSE

Previous studies have reported the association between frailty and stroke or Alzheimer's disease (AD). However, the causality remains unclear. The aim of the present study was to evaluate whether genetically predicted frailty is associated with the risk of stroke or AD by a Mendelian randomization (MR) study.

METHODS

Genetic variants associated with the frailty index (FI) were obtained from a large genome-wide association study (GWAS). Summary-level data for stroke and AD were adopted from the corresponding large GWAS of individuals of European ancestry. The inverse variance weighted method was used for estimating causal effects. Multivariable analysis was performed for further adjustment.

RESULTS

The present MR study indicated a suggestive association between genetically predicted FI and a higher risk of any stroke (odds ratio 1.360, 95% confidence interval 1.006-1.838, p = 0.046). Regarding the subtypes of stroke, genetically predicted FI was associated with a higher risk of large artery atherosclerosis stroke (LAS) (odds ratio 2.487, 95% confidence interval 1.282-4.826, p = 0.007). No causal links were identified between genetically predicted FI and any ischaemic stroke, intracranial haemorrhage, cardioembolic stroke, small artery stroke, AD or AD-by-proxy. Multivariable MR analysis indicated that the association of genetically predicted FI with LAS was attenuated after adjustment for inflammatory bowel disease (p = 0.114).

CONCLUSIONS

The MR study suggested that genetically predicted FI may be associated with an increased risk of any stroke. Subgroup analysis indicated a suggestive association between genetically predicted FI and the risk of LAS. The underlying mechanisms need further investigation.

Retinal blood vessel calibre and vascular ageing in a general Spanish population: A EVA study

INTRODUCTION

The aim of this work was to analyse the association of the retinal arteriolar calibre and the arteriole/venule index (AV index) with vascular ageing in a general population without previous cardiovascular disease.

MATERIALS AND METHODS

Descriptive cross-sectional study. A total of 482 individuals without cardiovascular disease (mean age: 55.6 ± 14.2 years) were selected by random sampling, stratified by age and sex. The retinal arteriolar calibre was measured using digital fundus images of the back of the eye captured with a validated, semiautomatized and computer-assisted software (Index calculator). Vascular ageing was defined using three criteria based on the values of: (1) Carotid-femoral Pulse Wave Velocity (cfPWV), (2) Brachial-ankle Pulse Wave Velocity (baPWV) and (3) Carotid Intima-Media Thickness.

RESULTS

The AV index and arteriolar calibre show a negative correlation with age, arterial pressure, cardiovascular risk and parameters of vascular structure and function (p < 0.001 in all cases). We found lower mean values of the AV index and arteriolar calibre in the individuals with early vascular ageing compared to those with healthy vascular ageing. AV index was negatively correlated with cfPWV ((β=-2.9; 95% CI (-4.7; -1.1)), baPWV ((β=-3.2; 95% CI (-5.4; -0.9)) and vascular ageing index ((β=-1.7; 95% CI (-2.7; -0.7)). Arteriolar calibre showed a negative correlation with baPWV (β=-0.1; 95% CI (-0.2; -0.1)). In the logistic regression analysis, lower values of AV index ((OR=0.01; 95% CI (0.01-0.10), OR=0.03; 95% CI (0.01-0.11) and OR=0.09; 95% CI (0.01-0.67)) were associated with EVA defined with cfPWV, baPWV and vascular ageing index respectively, and lower values of arteriolar calibre ((OR=0.71; 95% CI (0.55-0.91)) were associated with EVA defined with vascular ageing index.

CONCLUSIONS

Lower values of AV index and retinal arteriolar calibre were associated with vascular ageing in a general Spanish population without previous cardiovascular disease.

Ocular manifestations and refractive errors among people living with HIV in Pune, India: a cross-sectional study

Objective

We aimed to determine the ocular manifestation and refractive error prevalences among people living with HIV (PLHIV) in Pune, India.

Methods

This cross-sectional study included HIV-infected adults attending a National AIDS Research Institute clinic. Ophthalmologic examination included visual acuity estimation, refraction, orthoptic evaluation, slit lamp and fundus examination, and photography.

Results

In total, 441 HIV-infected individuals were enrolled. The participants' median age was 44 (interquartile range 38–49) years and 227 (51.5%) were men. Refractive errors occurred in 132 (29.9%) individuals. Ocular manifestations were present in 93 (21.1%) participants and the most frequent was cataract in 59 (13.4%) participants. Multivariate logistic regression analysis showed that participants who were illiterate (adjusted odds ratio [AOR] 2.80, 95% confidence interval [CI] 1.47–5.33) and those aged greater than 40 years (AOR 5.59, 95% CI 2.69–11.61) were more likely to have ocular manifestations. The odds of having ocular manifestations were greater in participants with treatment substitution or changes (AOR 2.11, 95% CI 1.16–3.82).

Conclusions

Cataract and refractive errors were prevalent among PLHIV. PLHIV should be encouraged to have regular ophthalmic checkups. Individuals with lower education levels and older age should be counseled regarding eye care and timely reporting of ocular symptoms.

Telomere length and frailty in older adults-A systematic review and meta-analysis

Telomere shortening has been proposed as a potentially useful biomarker of human ageing and age-related morbidity and mortality. We performed a systematic review and meta-analysis to summarize results from individual studies on the telomere length according to the frailty status and frailty index in older adults. We searched the PubMed, SCOPUS and Web of Science databases to identify studies that evaluated the telomere length in frail and non-frail older adults and the relationship between telomere length and frailty index score. We used the base pairs (bp) as a measure of the telomere length. Summary estimates were calculated using random-effects models. Nine studies were included in the present systematic review and a total of 10,079 older adults were analyzed. We found that the frail older adults (n = 355) had shorter telomeres than the non-frail (n = 1894) (Standardized Mean Difference [SMD] -0.41; 95% CI -0.73 to -0.09; P = 0.01; I² = 82%). Significant differences in telomere length between frail and non-frail older adults were identified in Hispanic (SMD -1.31; 95% CI -1.71 to -0.92; P < 0.0001; I² = 0%) but not in Non-Hispanic countries (SMD -0.13; 95% CI -0.26 to 0.00; P = 0.06; I² = 0%). Similar results were found in the adjusted meta-analysis (SMD -0.56; 95% -1.12 to 0.00; P = 0.05; I² = 85%). A significant but weak relationship was found between telomere length and frailty index analyzing 8244 individuals (SMD -0.06; 95% IC -0.10 to 0.01; P = 0.01; I² = 0%). The current available evidence suggests that telomere length may be not a meaningful biomarker for frailty. Because the potential influence of ethnicity in shortening of telomeres and decline in physiologic reserves associated with aging, additional multiethnic studies are needed.

Retinal microcirculation and leukocyte telomere length in the general population

Retinal arteriolar narrowing increases with age and predict adverse cardiovascular outcomes. Telomere length keeps track of the division of somatic cells and is a biomarker of biological age. We investigated to what extent retinal arteriolar diameters are associated with biological age, as captured by leukocyte telomere length (LTL). In 168 randomly selected Flemish participants from the family-based population study FLEMENGHO (mean age, 46.2 years) at baseline, of whom 85 underwent a follow-up examination (median, 4.1 years), we post-processed nonmydriatic retinal photographs and measured LTL. In men only, central retinal arteriolar equivalents (CRAE) and arteriole-to-venule ratio (AVR) were associated with LTL with stronger associations at higher age and body mass index. In men aged 57.6 years (75th percentile) a 20% shorter LTL was associated with a decrease in CRAE of 4.57 µm. A 20% shorter LTL was associated with a decrease of 5.88 µm in CRAE at a BMI of 29.9 kg/m2 (75th percentile). Similar associations were observed between AVR and LTL. In women, no retinal microvascular traits were associated with LTL. Retinal arteriolar narrowing in men but not in women is associated with biological age. Our findings support the idea that avoiding overweight contributes to maintaining a healthier microcirculation.

The association between telomere length and frailty: A systematic review and meta-analysis

BACKGROUND

Several studies have examined the association between telomere length and frailty, but results from these studies are contradictory. Therefore, we conducted a systematic review and meta-analysis to examine the association between telomere length and frailty.

METHODS

We searched the literature in Ovid (MEDLINE), Embase, PubMed, Web of Knowledge and Cochrane databases in July 2017 for studies evaluating the association of telomere length and the risk of frailty.

RESULTS

A total of 5 studies (3268 participants) were eligible in our study. The prevalence of frailty ranged from 5.4% to 51.1%. The pooled mean difference of telomere length for the non-frail versus frail was 0.06 (95% CI: -0.01, 0.13), suggesting that no significant association was found between telomere length and frailty. In addition, the subgroup analysis indicated that telomere length was not significantly associated with the risk of frailty in all gender groups. Similar results were also found when frailty was defined by the Fried criteria (mean difference = 0.07, 95% CI: -0.03, 0.16) and frailty index (mean difference = -0.02, 95% CI: -0.05, 0.01), but not by the frailty scale (mean difference = 0.18, 95% CI: 0.04, 0.32).

CONCLUSION

Telomere length is not associated with the risk of frailty. Well-designed prospective studies are needed to evaluate further whether telomere length is a meaningful biological marker for frailty.

Preterm infants have significantly longer telomeres than their term born counterparts

There are well-established morbidities associated with preterm birth including respiratory, neurocognitive and developmental disorders. However several others have recently emerged that characterise an 'aged' phenotype in the preterm infant by term-equivalent age. These include hypertension, insulin resistance and altered body fat distribution. Evidence shows that these morbidities persist into adult life, posing a significant public health concern. In this study, we measured relative telomere length in leukocytes as an indicator of biological ageing in 25 preterm infants at term equivalent age. Comparing our measurements with those from 22 preterm infants sampled at birth and from 31 term-born infants, we tested the hypothesis that by term equivalent age, preterm infants have significantly shorter telomeres (thus suggesting that they are prematurely aged). Our results demonstrate that relative telomere length is highly variable in newborn infants and is significantly negatively correlated with gestational age and birth weight in preterm infants. Further, longitudinal assessment in preterm infants who had telomere length measurements available at both birth and term age (n = 5) suggests that telomere attrition rate is negatively correlated with increasing gestational age. Contrary to our initial hypothesis however, relative telomere length was significantly shortest in the term born control group compared to both preterm groups and longest in the preterm at birth group. In addition, telomere lengths were not significantly different between preterm infants sampled at birth and those sampled at term equivalent age. These results indicate that other, as yet undetermined, factors may influence telomere length in the preterm born infant and raise the intriguing hypothesis that as preterm gestation declines, telomere attrition rate increases.

Acceleration of leukocytes' epigenetic age as an early tumor and sex-specific marker of breast and colorectal cancer

Changes in blood epigenetic age have been associated with several pathological conditions and have recently been described to anticipate cancer development. In this work, we analyze a publicly available leukocytes methylation dataset to evaluate the relation between DNA methylation age and the prospective development of specific types of cancer. We calculated DNA methylation age acceleration using five state-of-the-art estimators (three multi-site: Horvath, Hannum, Weidner; and two CpG specific: ELOV2 and FHL2) in a cohort including 845 subjects from the EPIC-Italy project and we compared 424 samples that remained cancer-free over the approximately ten years of follow-up with 235 and 166 subjects who developed breast and colorectal cancer, respectively. We show that the epigenetic age estimated from blood DNA methylation data is statistically significantly associated to future breast and male colorectal cancer development. These results are corroborated by survival analysis that shows significant association between age acceleration and cancer incidence suggesting that the chance of developing age-related diseases may be predicted by circulating epigenetic markers, with a dependence upon tumor type, sex and age estimator. These are encouraging results towards the non-invasive and perspective usage of epigenetic biomarkers.

The impact of age-related cataract on measures of frailty in an aging global population

PURPOSE OF REVIEW

To review the associations among age-related cataract, frailty, and frailty outcomes (e.g., disabilities).

RECENT FINDINGS

It is predicted that the proportion of the population aged 65 and older, in developed and developing nations alike, will rise until at least 2050. The proportion of patients suffering from cataracts and frailty is expected to increase, as are age-related diseases. Although there are many papers reporting on the association between frailty outcomes, cataract, and visual impairment, there is a relative paucity of papers describing associations between frailty markers, cataract, and visual impairment.

SUMMARY

Reports regarding the relationship between frailty, visual impairment, cataract, and cataract surgery are limited, but gradually increasing. Further research is expected to clarify the mechanism of visual function or the impact of restored vision on frailty. Evidence for the effect of cataract on frailty and frailty outcomes after restoring vision by cataract surgery remains limited.

Association of the Fractal Dimension of Retinal Arteries and Veins with Quantitative Brain MRI Measures in HIV-Infected and Uninfected Women

Objective

The fractal dimension of retinal arteries and veins is a measure of the complexity of the vascular tree. We hypothesized that retinal fractal dimension would be associated with brain volume and white matter integrity in HIV-infected women.

Design

Nested case-control within longitudinal cohort study.

Methods

Women were recruited from the Brooklyn site of the Women’s Interagency HIV study (WIHS); 34 HIV-infected and 21 HIV-uninfected women with analyzable MRIs and retinal photographs were included. Fractal dimension was determined using the SIVA software program on skeletonized retinal images. The relationship between predictors (retinal vascular measures) and outcomes (quantitative MRI measures) were analyzed with linear regression models. All models included age, intracranial volume, and both arterial and venous fractal dimension. Some models were adjusted for blood pressure, race/ethnicity, and HIV-infection.

Results

The women were 45.6 ± 7.3 years of age. Higher arterial dimension was associated with larger cortical volumes, but higher venous dimension was associated with smaller cortical volumes. In fully adjusted models, venous dimension was significantly associated with fractional anisotropy (standardized β = -0.41, p = 0.009) and total gray matter volume (β = -0.24, p = 0.03), and arterial dimension with mean diffusivity (β = -0.33,.p = 0.04) and fractional anisotropy (β = 0.34, p = 0.03). HIV-infection was not associated with any retinal or MRI measure.

Conclusions

Higher venous fractal dimension was associated with smaller cortical volumes and lower fractional anisotropy, whereas higher arterial fractal dimension was associated with the opposite patterns. Longitudinal studies are needed to validate this finding.

Telomere length analysis and preterm infant health: the importance of assay design in the search for novel biomarkers

Preterm infants develop an 'aged' phenotype in comparison with term-born infants, one component of which is adverse metabolic health and, therefore, long-term health follow-up is warranted to identify morbidity. In light of this, the identification and use of biomarkers to aid with prognosis would be a welcome development. Telomeres are repeat sequences at the ends of each chromosome arm known to shorten as a consequence of cellular aging, and in relation to several disease conditions. The hypothesis that expreterm infants manifest alterations in telomere attrition rate is, therefore, one of interest. Analysis of telomere length maybe a plausible technique to predict prognosis in relation to preterm birth, and early life environmental and nutritional exposures. In this article, we review the literature on telomere length analysis in the preterm infant population and examine the tools available to measure telomere length.

High tobacco consumption is causally associated with increased all-cause mortality in a general population sample of 55,568 individuals, but not with short telomeres: a Mendelian randomization study

BACKGROUND

High cumulative tobacco consumption is associated with short telomeres and with increased all-cause mortality. We tested the hypothesis that high tobacco consumption is causally associated with short telomeres and with increased all-cause mortality.

METHODS

We studied 55,568 individuals including 32,823 ever smokers from the Danish general population, of whom 3430 died during 10 years of follow-up. All had telomere length measured, detailed information on smoking history, and CHRNA3 rs1051730 genotype, which is associated with tobacco consumption, determined. In a Mendelian randomization study, we conducted observational, genetic, and mediation analyses.

RESULTS

First, tobacco consumption was 21.1 pack-years in non-carriers, 22.8 in heterozygotes and 24.8 in homozygotes (P-trend<0.001). Second, the observational multivariable adjusted hazard ratio for all-cause mortality was 1.12 [95% confidence interval (CI): 1.09, 1.15] per doubling in tobacco consumption. In Mendelian randomization analysis, the hazard ratio was 1.08 (1.02, 1.14) per minor CHRNA3 allele in ever smokers. Third, in observational analysis telomeres shortened with -13 base pairs (-18, -8) per doubling in tobacco consumption. In Mendelian randomization analysis, the estimate was +3 base pairs (-10, +15) per minor CHRNA3 allele. Finally, individuals with the shortest vs longest telomeres had a multivariable adjusted hazard ratio of 1.30 (1.13, 1.50) for all-cause mortality; however, in mediation analysis short telomeres explained only +0.4% (-3.5%, +4.3%) of the association between high tobacco consumption and increased all-cause mortality.

CONCLUSIONS

High tobacco consumption is causally associated with increased all-cause mortality. High cumulative tobacco consumption is associated with short telomeres observationally, but there is no clear genetic association.

Functional disability in community-dwelling elderly: the role of cataracts and contextual factors

Introduction Cataract arises as a risk factor for functional disability in elderly Objective: To determine differences in functional capacity and contextual factors associated with it in elderly affected and not affected by cataract and association between disability and cataracts.Methods A transversal-type observational study was carried out with 100 community elderly, divided into two groups: elderly affected (n = 50) and not affected by cataracts (n = 50). It was evaluated: activities of daily living (ADL) – Katz Index –, instrumental activities of daily living (IADL) – Lawton scale – and mobility – Short Physical Performance Battery. Functional disability was detected when the elderly were dependent or semi-dependent for one or more IADL or ADL and/or when they presented any difficulty in mobility. Data analysis included absolute and relative frequencies, Chi-squared or Fisher’s exact tests (p < 0.05) and Poisson regression.Results No statistically significant associations were observed between IADL, ADL or mobility disability and cataracts. A statistically significant difference was observed between the disabled elderly affected and not affected by cataract according to contextual factors for ADL regarding age (p = 0.037) and comorbidity (p = 0.037), for mobility regarding the practice of physical activity (p = 0.013), and for IADL (p = 0.001), ADL (p = 0.001) and mobility (p = 0.013) regarding the self-reporting of eyesight problems.Conclusions Besides cataracts, physical inactivity, comorbidity and functional aging itself are contributing factors to the process of disability in elderly, so, the physiotherapy is essential both to prevent as to reverse this process.

Ocular parameters of biological ageing in HIV-infected individuals in South Africa: relationship with chronological age and systemic biomarkers of ageing

HIV-infected individuals have an increased risk of age-related morbidity despite antiretroviral treatment (ART). Several anatomic and functional ophthalmological parameters are associated with increasing chronological age. These may, therefore, potentially serve as biomarkers of ageing. We investigated associations between ocular parameters (lens density, retinal vessel calibre, corneal endothelium and retinal nerve fibre layer thickness) and two 'cellular' biomarkers of ageing (leukocyte telomere length and CDKN2A expression) and with frailty in a cross-sectional study of 216 HIV-infected individuals. All ocular parameters, telomere length and frailty were associated with chronological age, whereas CDKN2A expression was not. Retinal venular calibre and lens density were associated with shorter telomere length (p-trend=0.04, and 0.08, respectively), whereas CDKN2A expression and frailty status were not associated with ocular parameters. Longitudinal studies are warranted to assess the integration of retinal vascular calibre and lens density with systemic markers to develop an overall index of biological ageing in HIV infection.