Telomere length predicts poststroke mortality, dementia, and cognitive decline

Material hardship and telomere length in children

Telomere length (TL) serves as a biomarker of exposure to stressors, including material hardship. Data from the Future of Families and Child Wellbeing Study (1998-2015) were utilized to determine whether prior material hardship was associated with shorter salivary TL at years 9 and 15. 49% of the year 9 study population were female, 49% were Black, and 25% were Hispanic. At year 9 (N = 1990), regression analyses found a significant association between prior material hardship and shorter TL (β = -.005, p < .01). Additionally, at year 15 (N = 1874), material hardship experienced during infancy and toddlerhood was associated with shorter TL (β = -.009, p < .01), pointing toward infancy and toddlerhood as a sensitive period.

Telomere length in early childhood and its association with attention: a study in 4-6 year old children

Telomere length (TL), a marker of cellular aging, has been studied in adults with regard to its connection to cognitive function. However, little is known about the association between TL and cognitive development in children. This study investigated the interplay between TL and cognitive functioning in 283 Belgian children aged four to six years of the Environmental Influence on Aging in Early Life (ENVIRONAGE) birth cohort. Child leukocyte TL was measured using qPCR, while cognitive functioning, including attention and memory, was assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB). Linear regression models were employed to examine the association between TL and cognitive outcomes, adjusting for potential confounders. We found an inverse association between TL and the spatial errors made during the Motor Screening task (p = 0.017), indicating a higher motor accuracy in children with longer telomeres. No significant associations were found between TL and other cognitive outcomes. Our results suggest a specific link between TL and motor accuracy but not with the other cognitive domains.

Analysis of telomere length and the relationship with neurocognitive functions in euthymic bipolar disorder: A cross-sectional pilot study

BACKGROUND

Telomere shortening has been considered a potential biological marker related to disease susceptibility and aging in psychiatric disorders. However, the relationship between telomere length and bipolar disorder (BD-I and BD-II) is uncertain. Moreover, whether telomere shortening is an independent factor of cognitive impairment in BD patients is still inconclusive.

METHODS

We explore telomere length and cognitive function in patients with bipolar disorder and the relationship between them. We enrolled three groups (35 patients with euthymic BD-I, 18 with euthymic BD-II, and 38 healthy controls). Telomere length was measured by fluorescent quantitative polymerase chain reaction (q-PCR), and cognitive function was evaluated by the MATRICS Consensus Cognitive Battery (MCCB). SPSS 24.0 was used for statistical analysis.

RESULTS

The telomere length of euthymic patients with BD-I and BD-II was shorter than that of healthy controls (F = 8.228, P = 0.001, η2 = 0.176). Telomere length was not significantly different between BD-I and BD-II. Compared to HCs, poor performance was detected in attention and vigilance in BD-I patients (F = 3.473, P = 0.036). Working memory was positively correlated with telomere length in BD-II patients (Beta = 0.5, P = 0.041, Adjusted R2 = 0.2).

CONCLUSIONS

The current study provided evidence of shortened telomere length in euthymic BD patients, indicating that telomere shortening might be a promising biomarker of susceptibility to bipolar disorder. The telomere length predicted the working memory in BD-II patients. Further studies are needed to clarify the role of accelerated aging on cognitive functioning in a young group of patients with BD.

Sex-specific differences in telomere length of patients with primary knee osteoarthritis

Accelerated telomere shortening is associated with age-related diseases, including osteoarthritis (OA). We aimed to determine the relative telomere length (TL) in leukocytes and cartilage of patients with primary knee OA and to investigate factors that may affect TL in OA. Relative TL measurements were performed using qPCR in leukocytes of 612 individuals (310 patients with primary knee OA undergoing total knee arthroplasty (TKA) and 302 unaffected controls). We also analysed cartilage in 57 of the 310 OA patients, measuring relative TL in severely affected and less affected (control) cartilage collected from the same knee. Cartilage TLs were compared to leukocyte TLs in all 57 patients. A significant sex-by-disease-status interaction was found in regard to relative TL. Controlling for age, the average difference of leukocyte TL between female OA patients versus female controls was 0.217 units greater than that between male OA patients versus male controls (95% CI; [0.014, 0.421]). Relative TL comparison of severely and less affected cartilage samples from the same joint showed attrition of telomeres corresponding to disease severity (0.345 mean TL difference with 95% CI of [0.151, 0.539]) in the joint. We also noted that both severely and less affected cartilage had shorter telomeres than leukocytes collected from the same patient. Severe and moderate pain in OA patients was associated with shorter TL in leukocytes, but there was no association with depression or smoking in leukocytes and cartilage. Our study indicates that sex is an important factor in OA contributing to leukocyte and cartilage TL and that pain in OA shows an inverse association only with leukocyte TL.

The associations of socioeconomic status with incident dementia and Alzheimer's disease are modified by leucocyte telomere length: a population-based cohort study

Socio-economic status (SES) and biological aging are risk factors for dementia, including Alzheimer's disease, however, it is less clear if the associations with SES vary sufficiently across different biological age strata. We used data from 331,066 UK Biobank participants aged 38-73 with mean follow-up of 12 years to examine if associations between SES (assessed by educational attainment, employment status and household income) and dementia and Alzheimer's disease are modified by biological age (assessed by leucocyte telomere length: LTL). Diagnosis of events was ascertained through hospital admissions data. Cox regressions were used to estimate hazard ratios [HRs]. A consistent dose-response relationship was found, with participants in low SES and shorter LTL strata (double-exposed group) reporting 3.28 (95% confidence interval [CI] 2.57-4.20) and 3.44 (95% CI 2.35-5.04) times higher risks of incident dementia and Alzheimer's disease respectively, compared to those of high SES and longer LTL (least-exposed group). Of interest is a synergistic interaction between SES and LTL to increase risk of dementia (RERI 0.57, 95% CI 0.07-1.06) and Alzheimer's disease (RERI 0.79, 95% CI 0.02-1.56). Our findings that SES and biological age (LTL) are synergistic risk factors of dementia and Alzheimer's disease may suggest the need to target interventions among vulnerable sub-groups.

Telomere length and stroke recurrence after ischemic stroke and TIA

BACKGROUND AND OBJECTIVE

Shortening telomere length (TL), as an indicator of aging, has been associated with increased risk of cardiovascular disease and incident stroke. However, there are limited data relating to the association between TL and recurrent stroke.

METHODS

Patients from the Third China National Stroke Registry who had whole genome sequencing (WGS) were selected. TL was estimated using TelSeq based on binary sequence alignment/map files derived from WGS data. Cox proportional hazards regression models were performed to assess the association of TL with recurrent stroke.

RESULTS

A total of 8041 patients with ischemic stroke (IS) or transient ischemic attack (TIA) were included. Mean TL was 2.14 ± 0.82 kb. Patients in the lowest tertile of TL had higher incidence of stroke recurrence compared to those in the middle and highest tertile (6.4% vs 5.9% vs 5.2%), but the difference was not longer significant after adjusting for age, sex, cardiovascular risk factors and stroke severity. Similarly, when analyzing TL as a continuous variable, the HR per 1000 bp increase in TL was significant 0.88 (0.79-0.98), but after adjusting for co-variates, was no longer significant (0.91; 95% confidence interval (CI), 0.81-1.02). In patients aged > 65 years, but not in younger patients, after adjusting for co-variates, TL was significantly associated with stroke recurrence. Compared to the lowest tertile, HRs (95% CI) after adjustment for all co-variates for the middle and highest tertiles were 0.78 (0.55-1.10) and 0.67 (0.46-0.98), respectively, with p for trend of 0.03. In analyses using TL as a continuous variable, adjusted HR (95% CI) per 1000 bp increase in TL was 0.80 (0.66-0.96). However, there was no significant interaction between TL and age on risk of stroke recurrence (p for interaction = 0.09).

CONCLUSIONS

In Chinese IS or TIA patients, no independent association was found between TL and risk of stroke recurrence after adjusting for co-variates. We found a possible association in older patients but this needs replicating.

Association of dietary inflammatory index and leukocyte telomere length with mild cognitive impairment in Chinese older adults

BACKGROUND

There are minimal data on the relationship between DII and MCI in an elderly Chinese population and no research has assessed the potential effect of LTL.

OBJECTIVE

We investigated the association between DII and MCI while taking into account the potential effect of LTL.

METHODS

This cross-sectional study included 3,386 participants aged ≥ 60 years of age from the Tianjin Elderly Nutrition and Cognition Cohort study. DII score was constructed based on a validated self-administered food frequency questionnaire was calculated based on the method developed by Shivappa et al. LTL was measured by quantitative real-time polymerase chain reaction. Multivariable logistic regression analysis was used to analyze the association between DII, LTL and MCI. Moreover, mediation analysis was employed to test the mediation effect of LTL on the total effect of DII on MCI.

RESULTS

Compared with the participants in the lowest tertiles of LTL and DII score, the odds ratios (ORs) of MCI in the highest tertiles were 0.386(95% CI: 0.281-0.529) and 1.650 (95% CI: 1.232-2.209), respectively. The significant association between DII score and MCI persisted after further adjusting for LTL (OR: 1.595; 95% CI: 1.189-2.140). The link between DII score and MCI was mediated partially by LTL (βindirect effect= -0.008, P<0.05).

CONCLUSION

High DII score was positively associated with MCI prevalence in an elderly Chinese population and the link between DII scores and MCI seemed to be mediated partially by LTL.

Induced pluripotent stem cell-derived and directly reprogrammed neurons to study neurodegenerative diseases: The impact of aging signatures

Many diseases of the central nervous system are age-associated and do not directly result from genetic mutations. These include late-onset neurodegenerative diseases (NDDs), which represent a challenge for biomedical research and drug development due to the impossibility to access to viable human brain specimens. Advancements in reprogramming technologies have allowed to obtain neurons from induced pluripotent stem cells (iPSCs) or directly from somatic cells (iNs), leading to the generation of better models to understand the molecular mechanisms and design of new drugs. Nevertheless, iPSC technology faces some limitations due to reprogramming-associated cellular rejuvenation which resets the aging hallmarks of donor cells. Given the prominent role of aging for the development and manifestation of late-onset NDDs, this suggests that this approach is not the most suitable to accurately model age-related diseases. Direct neuronal reprogramming, by which a neuron is formed via direct conversion from a somatic cell without going through a pluripotent intermediate stage, allows the possibility to generate patient-derived neurons that maintain aging and epigenetic signatures of the donor. This aspect may be advantageous for investigating the role of aging in neurodegeneration and for finely dissecting underlying pathological mechanisms. Here, we will compare iPSC and iN models as regards the aging status and explore how this difference is reported to affect the phenotype of NDD in vitro models.

Genetically predicted telomere length and Alzheimer’s disease endophenotypes: a Mendelian randomization study

Telomere length (TL) is associated with biological aging, consequently influencing the risk of age-related diseases such as Alzheimer’s disease (AD). We aimed to evaluate the potential causal role of TL in AD endophenotypes (i.e., cognitive performance, N = 2233; brain age and AD-related signatures, N = 1134; and cerebrospinal fluid biomarkers (CSF) of AD and neurodegeneration, N = 304) through a Mendelian randomization (MR) analysis. Our analysis was conducted in the context of the ALFA (ALzheimer and FAmilies) study, a population of cognitively healthy individuals at risk of AD. A total of 20 single nucleotide polymorphisms associated with TL were used to determine the effect of TL on AD endophenotypes. Analyses were adjusted by age, sex, and years of education. Stratified analyses by APOE-ɛ4 status and polygenic risk score of AD were conducted. MR analysis revealed significant associations between genetically predicted longer TL and lower levels of CSF Aβ and higher levels of CSF NfL only in APOE-ɛ4 non-carriers. Moreover, inheriting longer TL was associated with greater cortical thickness in age and AD-related brain signatures and lower levels of CSF p-tau among individuals at a high genetic predisposition to AD. Further observational analyses are warranted to better understand these associations.

Integrative analysis of DNA methylation and gene expression identifies genes associated with biological aging in Alzheimer's disease

Introduction

The acceleration of biological aging is a risk factor for Alzheimer's disease (AD). Here, we performed weighted gene co-expression network analysis (WGCNA) to identify modules and dysregulated genesinvolved in biological aging in AD.

Methods

We performed WGCNA to identify modules associated with biological clocks and hub genes of the module with the highest module significance. In addition, we performed differential expression analysis and association analysis with AD biomarkers.

Results

WGCNA identified five modules associated with biological clocks, with the module designated as "purple" showing the strongest association. Functional enrichment analysis revealed that the purple module was related to cell migration and death. Ten genes were identified as hub genes in purple modules, of which CX3CR1 was downregulated in AD and low levels of CX3CR1 expression were associated with AD biomarkers.

Conclusion

Network analysis identified genes associated with biological clocks, which suggests the genetic architecture underlying biological aging in AD.

Highlights

Examine links between Alzheimer's disease (AD) peripheral transcriptome and biological aging changes.Weighted gene co-expression network analysis (WGCNA) found five modules related to biological aging.Among the hub genes of the module, CX3CR1 was downregulated in AD.The CX3CR1 expression level was associated with cognitive performance and brain atrophy.

Analysis of Telomere Length and Its Implication in Neurocognitive Functions in Elderly Women

During the normal aging process, a series of events occur, such as a decrease in telomere length and a decrease in various cognitive functions, such as attention, memory, or perceptual-motor speed. Several studies have attempted to establish a correlation between both variables; however, there is considerable controversy in the scientific literature. The aim of our study was to establish a correlation between the scores obtained in the following different cognitive tests: the Mini-Mental State Examination, the Benton Visual Retention Test, the Trail Making Test, the Rey Auditory Verbal Learning Test, the Stroop Test, and the measurement of telomere length. The sample consisted of a total of 41 physically active, healthy women, with a mean age of 71.21 (±4.32) and of 33 physically inactive, healthy women, with a mean age of 72.70 (±4.13). Our results indicate that there is no correlation between the scores obtained by the women in either group and their telomere length. Therefore, it is not possible to conclude that telomere length can be correlated with cognitive performance.

Telomere length as a biomarker of aging and diseases

As research related to healthspan and lifespan has become a hot topic, the necessity for a reliable and practical biomarker of aging (BoA), which can provide information about mortality and morbidity risk, along with remaining life expectancy, has increased. The chromosome terminus non-coding protective structure that prevents genomic instability is called a telomere. The continual shortening of telomeres, which affects their structure as well as function, is a hallmark of agedness. The aforementioned process is a potential cause of age-related diseases (ARDs), leading to a bad prognosis and a low survival rate, which compromise health and longevity. Hence, studies scrutinizing the BoAs often include telomere length (TL) as a prospective candidate. The results of these studies suggest that TL measurement can only provide an approximate appraisal of the aging rate, and its implementation into clinical practice and routine use as a BoA has many limitations and challenges. Nevertheless, measuring TL while determining other biomarkers can be used to assess biological age. This review focuses on the importance of telomeres in health, senescence, and diseases, as well as on summarizing the results and conclusions of previous studies evaluating TL as a potential BoA.

Metabolic Signature of Leukocyte Telomere Length in Elite Male Soccer Players

Introduction: Biological aging is associated with changes in the metabolic pathways. Leukocyte telomere length (LTL) is a predictive marker of biological aging; however, the underlying metabolic pathways remain largely unknown. The aim of this study was to investigate the metabolic alterations and identify the metabolic predictors of LTL in elite male soccer players.

Methods: Levels of 837 blood metabolites and LTL were measured in 126 young elite male soccer players who tested negative for doping abuse at anti-doping laboratory in Italy. Multivariate analysis using orthogonal partial least squares (OPLS), univariate linear models and enrichment analyses were conducted to identify metabolites and metabolic pathways associated with LTL. Generalized linear model followed by receiver operating characteristic (ROC) analysis were conducted to identify top metabolites predictive of LTL.

Results: Sixty-seven metabolites and seven metabolic pathways showed significant associations with LTL. Among enriched pathways, lysophospholipids, benzoate metabolites, and glycine/serine/threonine metabolites were elevated with longer LTL. Conversely, monoacylglycerols, sphingolipid metabolites, long chain fatty acids and polyunsaturated fatty acids were enriched with shorter telomeres. ROC analysis revealed eight metabolites that best predict LTL, including glutamine, N-acetylglutamine, xanthine, beta-sitosterol, N2-acetyllysine, stearoyl-arachidonoyl-glycerol (18:0/20:4), N-acetylserine and 3-7-dimethylurate with AUC of 0.75 (0.64–0.87, p < 0.0001).

Conclusion: This study characterized the metabolic activity in relation to telomere length in elite soccer players. Investigating the functional relevance of these associations could provide a better understanding of exercise physiology and pathophysiology of elite athletes.

Fat metabolism is associated with telomere length in six population-based studies

Telomeres are repetitive DNA sequences located at the end of chromosomes, which are associated to biological aging, cardiovascular disease, cancer, and mortality. Lipid and fatty acid metabolism have been associated with telomere shortening. We have conducted an in-depth study investigating the association of metabolic biomarkers with telomere length (LTL). We performed an association analysis of 226 metabolic biomarkers with LTL using data from 11 775 individuals from six independent population-based cohorts (BBMRI-NL consortium). Metabolic biomarkers include lipoprotein lipids and subclasses, fatty acids, amino acids, glycolysis measures and ketone bodies. LTL was measured by quantitative polymerase chain reaction or FlowFISH. Linear regression analysis was performed adjusting for age, sex, lipid-lowering medication and cohort-specific covariates (model 1) and additionally for body mass index (BMI) and smoking (model 2), followed by inverse variance-weighted meta-analyses (significance threshold pmeta = 6.5x10-4). We identified four metabolic biomarkers positively associated with LTL, including two cholesterol to lipid ratios in small VLDL (S-VLDL-C % and S-VLDL-ce %) and two omega-6 fatty acid ratios (FAw6/FA and LA/FA). After additionally adjusting for BMI and smoking, these metabolic biomarkers remained associated with LTL with similar effect estimates. In addition, cholesterol esters in very small VLDL (XS-VLDL-ce) became significantly associated with LTL (p = 3.6x10-4). We replicated the association of FAw6/FA with LTL in an independent dataset of 7845 individuals (p = 1.9x10-4). To conclude, we identified multiple metabolic biomarkers involved in lipid and fatty acid metabolism that may be involved in LTL biology. Longitudinal studies are needed to exclude reversed causation.

Telomeres and Age-Related Diseases

Telomeres are at the non-coding ends of linear chromosomes. Through a complex 3-dimensional structure, they protect the coding DNA and ensure appropriate separation of chromosomes. Aging is characterized by a progressive shortening of telomeres, which compromises their structure and function. Because of their protective function for genomic DNA, telomeres appear to play an important role in the development and progression of many age-related diseases, such as cardiovascular disease (CVD), malignancies, dementia, and osteoporosis. Despite substantial evidence that links telomere length with these conditions, the nature of these observations remains insufficiently understood. Therefore, future studies should address the question of causality. Furthermore, analytical methods should be further improved with the aim to provide informative and comparable results. This review summarize the actual knowledge of telomere biology and the possible implications of telomere dysfunction for the development and progression of age-related diseases. Furthermore, we provide an overview of analytical techniques for the measurement of telomere length and telomerase activity.

Lifetime Observation of Cognition and Physiological Parameters in Male Mice

Laboratory mice are predominantly used for one experiment only, i.e., new mice are ordered or bred for every new experiment. Moreover, most experiments use relatively young mice in the range of late adolescence to early adulthood. As a consequence, little is known about the day-to-day life of adult and aged laboratory mice. Here we present a long-term data set with three consecutive phases conducted with the same male mice over their lifetime in order to shed light on possible long-term effects of repeated cognitive stimulation. One third of the animals was trained by a variety of learning tasks conducted up to an age of 606 days. The mice were housed in four cages with 12 animals per cage; only four mice per cage had to repeatedly solve cognitive tasks for getting access to water using the IntelliCage system. In addition, these learner mice were tested in standard cognitive tests outside their home-cage. The other eight mice served as two control groups living in the same environment but without having to solve tasks for getting access to water. One control group was additionally placed on the test set-ups without having to learn the tasks. Next to the cognitive tasks, we took physiological measures (body mass, resting metabolic rate) and tested for dominance behavior, and attractivity in a female choice experiment. Overall, the mice were under surveillance until they died a natural death, providing a unique data set over the course of virtually their entire lives. Our data showed treatment differences during the first phase of our lifetime data set. Young learner mice showed a higher activity, less growth and resting metabolic rate, and were less attractive for female mice. These effects, however, were not preserved over the long-term. We also did not find differences in dominance or effects on longevity. However, we generated a unique and valuable set of long-term behavioral and physiological data from a single group of male mice and note that our long-term data contribute to a better understanding of the behavioral and physiological processes in male C57Bl/6J mice.

Short leukocyte telomeres predict 25-year Alzheimer's disease incidence in non-APOE ε4-carriers

BACKGROUND

Leukocyte telomere length (LTL) has been shown to predict Alzheimer's disease (AD), albeit inconsistently. Failing to account for the competing risks between AD, other dementia types, and mortality, can be an explanation for the inconsistent findings in previous time-to-event analyses. Furthermore, previous studies indicate that the association between LTL and AD is non-linear and may differ depending on apolipoprotein E (APOE) ε4 allele carriage, the strongest genetic AD predictor.

METHODS

We analyzed whether baseline LTL in interaction with APOE ε4 predicts AD, by following 1306 initially non-demented subjects for 25 years. Gender- and age-residualized LTL (rLTL) was categorized into tertiles of short, medium, and long rLTLs. Two complementary time-to-event models that account for competing risks were used; the Fine-Gray model to estimate the association between the rLTL tertiles and the cumulative incidence of AD, and the cause-specific hazard model to assess whether the cause-specific risk of AD differed between the rLTL groups. Vascular dementia and death were considered competing risk events. Models were adjusted for baseline lifestyle-related risk factors, gender, age, and non-proportional hazards.

RESULTS

After follow-up, 149 were diagnosed with AD, 96 were diagnosed with vascular dementia, 465 died without dementia, and 596 remained healthy. Baseline rLTL and other covariates were assessed on average 8 years before AD onset (range 1-24). APOE ε4-carriers had significantly increased incidence of AD, as well as increased cause-specific AD risk. A significant rLTL-APOE interaction indicated that short rLTL at baseline was significantly associated with an increased incidence of AD among non-APOE ε4-carriers (subdistribution hazard ratio = 3.24, CI 1.404-7.462, P = 0.005), as well as borderline associated with increased cause-specific risk of AD (cause-specific hazard ratio = 1.67, CI 0.947-2.964, P = 0.07). Among APOE ε4-carriers, short or long rLTLs were not significantly associated with AD incidence, nor with the cause-specific risk of AD.

CONCLUSIONS

Our findings from two complementary competing risk time-to-event models indicate that short rLTL may be a valuable predictor of the AD incidence in non-APOE ε4-carriers, on average 8 years before AD onset. More generally, the findings highlight the importance of accounting for competing risks, as well as the APOE status of participants in AD biomarker research.

The association between telomere length and ischemic stroke risk and phenotype

The chronological age of a person is a key determinant of etiology and prognosis in the setting of ischemic stroke. Telomere length, an indicator of biological aging, progressively shortens with every cell cycle. Herein, we determined telomere length from peripheral blood leukocytes by Southern blot analyses in a prospective cohort of ischemic stroke patients (n = 163) and equal number of non-stroke controls and evaluated its association with various ischemic stroke features including etiology, severity, and outcome. A shorter telomere length (i.e. lowest quartile; ≤ 5.5 kb) was significantly associated with ischemic stroke (OR 2.95, 95% CI 1.70–5.13). This significant relationship persisted for all stroke etiologies, except for other rare causes of stroke. No significant association was present between admission lesion volume and telomere length; however, patients with shorter telomeres had higher admission National Institutes of Health Stroke Scale scores when adjusted for chronological age, risk factors, etiology, and infarct volume (p = 0.046). On the other hand, chronological age, but not telomere length, was associated with unfavorable outcome (modified Rankin scale > 2) and mortality at 90 days follow-up. The association between shorter telomere length and more severe clinical phenotype at the time of admission, might reflect reduced resilience of cerebral tissue to ischemia as part of biological aging.

Senescence and Inflammatory Markers for Predicting Clinical Progression in Parkinson's Disease: The ICICLE-PD Study

Background:

Cognitive decline is a frequent complication of Parkinson’s disease (PD) and the identification of predictive biomarkers for it would help in its management.

Objective:

Our aim was to analyse whether senescence markers (telomere length, p16 and p21) or their change over time could help to better predict cognitive and motor progression of newly diagnosed PD patients. We also compared these senescence markers to previously analysed markers of inflammation for the same purpose.

Methods:

This study examined the association of blood-derived markers of cell senescence and inflammation with motor and cognitive function over time in an incident PD cohort (the ICICLE-PD study). Participants (154 newly diagnosed PD patients and 99 controls) underwent physical and cognitive assessments over 36 months of follow up. Mean leukocyte telomere length and the expression of senescence markers p21 and p16 were measured at two time points (baseline and 18 months). Additionally, we selected five inflammatory markers from existing baseline data.

Results:

We found that PD patients had shorter telomeres at baseline and 18 months compared to age-matched healthy controls which also correlated to dementia at 36 months. Baseline p16 levels were associated with faster rates of motor and cognitive decline over 36 months in PD cases, while a simple inflammatory summary score at baseline best predicted cognitive score over this same time period in PD patients.

Conclusion:

Our study suggests that both inflammatory and senescence markers (p16) are valuable predictors of clinical progression in PD patients.

[Accelerated telomere erosion in schizophrenia: A literature review]

Schizophrenia is associated with a weighted average of 14.5 years of potential life lost according to a recent meta-analysis. This is partly explained by high rates of suicide and a high prevalence of non-psychiatric comorbidity (cardiovascular diseases, diabetes, cancers…). However, all these causes could not fully explain the loss of life expectancy in people suffering from schizophrenia. Life expectancy has been strongly correlated with telomere length (TL). Telomeres are noncoding structures consisting of DNA TTAGGG tandem repeats and associated proteins located at the end of the chromosomes. Their role is to help preserve genome stability by protecting chromosomal ends from the loss of genetic material. The progressive loss of telomeric material during cell divisions has led researchers to consider telomeres as molecular clocks that measure the number of divisions left until cellular death. The fact that both shorter telomeres and schizophrenia have been associated with a decrease in life expectancy has fueled the interest in the study of TL in schizophrenia. In this article, after a detailed review of the literature on the relationships between telomere length and schizophrenia, we discuss the different pathophysiological mechanisms which might explain this association. Based on this analysis, in the last part of the article we discuss potential research, therapeutic and prevention prospects. To date, the majority of the studies and meta-analyses found a decrease in TL in subjects with schizophrenia compared to control subjects. Conversely, all the studies exploring the TL in subjects suffering from first episode psychosis (FEP) have shown no significant difference from TL in control subjects. This suggests that excessive shortening of telomeres occurs during the course of the disease, thus it seems more probable that schizophrenia (or processes associated with it) affects TL rather than telomere erosion being a cause of the disorder. Several pathophysiological, non-mutually exclusive mechanisms have been proposed to explain the observed data. A first hypothesis to explain the acceleration of the physiological process of telomere erosion in schizophrenia is the activation of inflammation processes and oxidative stress as a consequence of schizophrenia per se. However, it seems more probable that reduced TL may be a result of cumulative exposure to chronic stress related to schizophrenia. Indeed, in healthy individuals a growing body of evidence has linked chronic stress to accelerated shortening of TL. This might explain why telomere erosion is too small to be detected in FEP patients who are younger and have a shorter duration of illness than subjects with schizophrenia. Based on these both explanations, telomere alterations may be considered as a biomarker of illness progression and might be useful for illness staging. Identifying processes associated with TL reduction might improve our understanding of the increased mortality and morbidity in schizophrenia, improve reliability of diagnosis, and hopefully suggest means for prevention and/or treatment. Treatments that prevent exposure and/or vulnerability to stressful life events that ameliorate schizophrenia may also prevent or decelerate telomere erosion. In this perspective, engaging subjects suffering from schizophrenia in a healthy diet and regular activity could be both promising strategies to protect telomere maintenance and improve health span at old age. In addition, the inflammatory process and oxidative stress involved in the physiopathology in at least a subgroup of subjects with schizophrenia could also be responsible for telomere erosion. Thus, an efficient anti-inflammatory therapeutic approach that targets these specific pathways could be of interest in this subgroup to limit telomere erosion. Mindfulness-based stress reduction (MBSR) therapies have been shown to reduce telomere erosion by increasing telomerase activity, although these psychological therapies should be used carefully in psychosis. Finally, advancing our understanding of the relationship between stress, inflammation and TL is of great interest for psychiatric research and for understanding stress effects in this population.

Telomere Length and Oxidative Stress and Its Relation with Metabolic Syndrome Components in the Aging

Simple Summary

A link between telomere length and some age-related diseases has been identified, including metabolic syndrome. So far, there is no mechanism to explain the origin or cause of telomere shortening in this syndrome; however, oxidative stress is a constant factor. Therefore, we reviewed scientific evidence that supported the association between oxidative stress and telomere length dynamics, also examining how each of the metabolic syndrome components individually affects the length. In this regard, there is strong scientific evidence that an increase in the number of metabolic syndrome components is associated with a shorter telomere length, oxidative damage at the lipid and DNA level, and inflammation, as well as its other components, such as obesity, hyperglycemia, and hypertension, while for dyslipidemia, there is a little more discrepancy. The difficulty for the correct treatment of metabolic syndrome lies in its multifactorial nature. Hence, there is a need to carry out more studies on healthy lifestyles during aging to prevent and reduce oxidative damage and telomere wear during aging, and consequently the progression of chronic degenerative diseases, thus improving the living conditions of older people.

Abstract

A great amount of scientific evidence supports that Oxidative Stress (OxS) can contribute to telomeric attrition and also plays an important role in the development of certain age-related diseases, among them the metabolic syndrome (MetS), which is characterised by clinical and biochemical alterations such as obesity, dyslipidaemia, arterial hypertension, hyperglycaemia, and insulin resistance, all of which are considered as risk factors for type 2 diabetes mellitus (T2DM) and cardiovascular diseases, which are associated in turn with an increase of OxS. In this sense, we review scientific evidence that supports the association between OxS with telomere length (TL) dynamics and the relationship with MetS components in aging. It was analysed whether each MetS component affects the telomere length separately or if they all affect it together. Likewise, this review provides a summary of the structure and function of telomeres and telomerase, the mechanisms of telomeric DNA repair, how telomere length may influence the fate of cells or be linked to inflammation and the development of age-related diseases, and finally, how the lifestyles can affect telomere length.

Associations Between Experience of Early Childhood Trauma and Impact on Obesity Status, Health, as Well as Perceptions of Obesity-Related Health Care

OBJECTIVE

To evaluate the association between obesity and history of childhood trauma in an effort to define implications for the provider-patient relationship and possible causes of failure of obesity treatment.

METHODS

Multisite survey developed by the Patient-Centered Outcomes Research Institute Learning Health Systems Obesity Cohort Workgroup consisting of 49 questions with 2 questions focusing on history of being a victim of childhood physical and/or sexual abuse was mailed to 19,964 overweight or obese patients. Data collection for this survey occurred from October 27, 2017, through March 1, 2018.

RESULTS

Among the 2211 surveys included in analysis, respondents reporting being a victim of childhood abuse increased significantly with obesity (23.6%, 26.0%, 29.1%, and 36.8% for overweight, class I, class II, and class III obesity, respectively; P<.001). A higher percentage of those who reported being a victim of childhood abuse noted that their weight issues began at an earlier age (P=.002) and were more likely to have weight-related comorbidities (P<.001), even after controlling for body mass index. Impacting physician counseling on weight loss, patients who were childhood victims of abuse reported lower self-esteem (P<.001), were more likely to feel judged by their health care providers (P=.009), and less likely to feel being treated with respect (P=.045).

CONCLUSION

Overall, being a victim of childhood abuse was significantly associated with obesity, lower self-esteem and negative experiences interacting with health care providers. Health care providers should receive training to ensure open and nonjudgmental visits with obese patients and consider the role of trauma survivorship issues in patients' development of obesity and health care experiences.

Premature Aging Among Trauma Survivors-The Longitudinal Implications of Sleep Disruptions on Telomere Length and Cognitive Performance

OBJECTIVES

Sleep is necessary for brain function as well as physical and cognitive processes. Sleep disruptions, common with aging, intensify among trauma survivors. Moreover, former prisoners-of-war (ex-POWs) often experience premature aging. This study investigates the longitudinal effects of sleep disruptions for ex-POWs in relation to cognitive performance and telomere length as well as between cognition and telomeres.

METHOD

This study included Israeli veterans from the 1973 Yom Kippur War who participated in four assessments (1991, 2003, 2008, 2015): (a) ex-POWs (n = 99), and (b) veterans who not were captured (controls) (n = 101). Among both groups, sleep disruptions were assessed using a self-report item in all four assessments. Cognitive performance was assessed using the Montreal Cognitive Assessment (MOCA) and telomere length was assessed via total white blood cells (leukocytes) from whole blood samples using Southern blot, both were measured only among ex-POWs in 2015. We conducted descriptive statistics, repeated measures, correlations, and path analyses.

RESULTS

Sleep disruptions were related to lower cognitive performance but not to shorter telomeres. Moreover, cognitive performance and telomere length were found to be related when sleep disruptions were taken into consideration.

CONCLUSION

Interpersonal trauma was shown to be a unique experience resulting in sleep disruptions over time, leading to cognitive impairment. These findings highlight the importance of viewing trauma survivors at high-risk for sleep disruptions. Therefore, it is imperative to inquire about sleep and diagnose cognitive disorders to help identify and treat premature aging.

The Association Between Leukocyte Telomere Length and Cognitive Performance Among the American Elderly

Background

Age-related cognitive decline begins in middle age and persists with age. Leukocyte telomere length (LTL) decreases with age and is enhanced by inflammation and oxidative stress. However, whether shorter LTL correlates with cognitive decline remains controversial.

Aims

We aimed to investigate the relationship between LTL and cognitive decline in the American elderly.

Methods

We used data from the 1999 to 2002 U.S. National Health and Nutrition Examination Survey (NHANES). We included participants aged 65–80 with available data on LTL and cognitive assessments. The cognitive function assessment used the digit symbol substitution test (DSST). We applied multivariate modeling to estimate the association between LTL and cognitive performance. Additionally, to ensure robust data analysis, we converted LTL into categorical variables through quartile and then calculated the P for trend.

Results

After adjusting for age, cardiovascular disease (CAD) score, gender, race, body mass index (BMI), and educational level, LTL showed a positive correlation with DSST score (odds ratio [OR] 3.47 [0.14, 6.79], P = 0.04). Additionally, to further quantify the LTL–DSST interaction, we found a similar trend when LTL was regarded as a categorical variable (quartile) (P for trend = 0.03).

Conclusion

LTL was associated with cognitive capabilities among the elderly, implying that LTL might be a biomarker of cognitive aging.

Leukocyte Telomere Length Is Unrelated to Cognitive Performance Among Non-Demented and Demented Persons: An Examination of Long Life Family Study Participants

OBJECTIVE

Leukocyte telomere length (LTL) is a widely hypothesized biomarker of biological aging. Persons with shorter LTL may have a greater likelihood of developing dementia. We investigate whether LTL is associated with cognitive function, differently for individuals without cognitive impairment versus individuals with dementia or incipient dementia.

METHOD

Enrolled subjects belong to the Long Life Family Study (LLFS), a multi-generational cohort study, where enrollment was predicated upon exceptional family longevity. Included subjects had valid cognitive and telomere data at baseline. Exclusion criteria were age ≤ 60 years, outlying LTL, and missing sociodemographic/clinical information. Analyses were performed using linear regression with generalized estimating equations, adjusting for sex, age, education, country, generation, and lymphocyte percentage.

RESULTS

Older age and male gender were associated with shorter LTL, and LTL was significantly longer in family members than spouse controls (p < 0.005). LTL was not associated with working or episodic memory, semantic processing, and information processing speed for 1613 cognitively unimpaired individuals as well as 597 individuals with dementia or incipient dementia (p < 0.005), who scored significantly lower on all cognitive domains (p < 0.005).

CONCLUSIONS

Within this unique LLFS cohort, a group of families assembled on the basis of exceptional survival, LTL is unrelated to cognitive ability for individuals with and without cognitive impairment. LTL does not change in the context of degenerative disease for these individuals who are biologically younger than the general population.

Leukocyte Telomere Length Shortening and Alzheimer's Disease Etiology

BACKGROUND

Several observational studies have found leukocyte telomere length (TL) to be associated with Alzheimer's diseases (AD) or dementia. However, these findings were based on small sample sizes and cannot clarify whether this relationship was causal. Genome-wide association studies (GWAS) have identified common variants associated with TL, providing a valuable resource for examining the causal effect of TL on AD using Mendelian Randomization (MR) methods.

OBJECTIVE

To examine if TL was causally associated with AD using GWAS summary statistics.

METHODS

Using a genetic risk score comprised of seven variants associated with leukocyte TL as an instrumental variable, we tested whether shorter TL was associated with a higher risk of AD by applying an MR approach to the summarized genome-wide association study data.

RESULTS

The genetic risk score for TL was associated with higher risk of AD [log-odds ratio (OR) = 0.003 for per TL-decreasing allele; 95% confidence interval (CI): 0.001, 0.005, p = 0.005]. Moreover, the MR analysis provided support for shorter TL to be causally associated with a higher risk of AD (log-OR = 0.04 per SD-decrease of TL; 95% CI: 0.01, 0.08, p = 0.01).

CONCLUSION

We suggest that TL has a causal effect on the risk of AD.

The functional and structural connectomes of telomere length and their association with cognition in mild cognitive impairment

Previous findings on the relationship between telomere length and cognition have inconclusive, despite the relatively consistent telomere-shortening associated atrophy in the subcortical regions. Perhaps, there could be other more important telomere-associated factors in the brain, such as functional connectivity (FC) and structural connectivity (SC) that modulate cognition. The current study examined the relationship between telomere length, connectivity, and cognition. Telomere length measurements, neurocognitive scores, diffusion tensor and resting-state functional magnetic resonance imaging scans were collected from 82 older adults with mild cognitive impairment. SC and FC matrices were derived from these scans and, in various combinations, entered into connectome-based predictive models to predict telomere length. The telomere-associated features were then used to predict memory and executive functions. Leave-one-out cross-validation was performed. Predictive accuracy was assessed via the correlation between predicted and observed scores (r_{predicted-observed}). Correlation analyses were carried out between cognition and telomere length. Telomere length was significantly and negatively correlated with executive functions (EF), after controlling for demographical confounds. Telomere length was best predicted by negative SC and positive FC features (r_{predicted-observed} = .57; p < .001). The telomere-associated negative SC features significantly predicted EF scores (r_{predicted-observed} = -.26; p = .015). Telomere-shortening was associated with better EF and alterations in both FC and SC. This enhanced EF can be partly attributed to the telomere-associated changes in SC. Given that telomere is known to be a nonspecific marker of health, our findings illustrated a potential clinical use of telomere length to predict individualized health-related information from FC and SC features.

Telomere length in depression and association with therapeutic response to electroconvulsive therapy and cognitive side-effects

BACKGROUND

Electroconvulsive therapy (ECT) is the most acutely effective treatment for severe treatment-resistant depression. However, there are concerns about its cognitive side-effects and we cannot yet confidently predict who will experience these. Telomeres are DNA-protein complexes that maintain genomic integrity. In somatic cells, telomeres shorten with each cell division. Telomere length (TL) can thus provide a measure of 'biological' aging. TL appears to be reduced in depression, though results are mixed. We sought to test the following hypotheses: (1) that TL would be shorter in patients with depression compared to controls; (2) that TL would be a predictor of response to ECT; and (3) that shorter TL would predict cognitive side-effects following ECT.

METHOD

We assessed TL in whole blood DNA collected from severely depressed patients (n = 100) recruited as part of the EFFECT-Dep Trial and healthy controls (n = 80) using quantitative real-time polymerase chain reaction. Mood and selected cognitive measures, including global cognition, re-orientation time, and autobiographical memory, were obtained pre-/post-ECT and from controls.

RESULTS

Our results indicate that TL does not differ between patients with depression compared to controls. TL itself was not associated with mood ratings and did not predict the therapeutic response to ECT. Furthermore, shorter baseline TL is not a predictor of cognitive side-effects post-ECT.

CONCLUSIONS

Overall, TL assessed by PCR does not represent a useful biomarker for predicting the therapeutic outcomes or risk for selected cognitive deficits following ECT.

Mendelian randomization implies no direct causal association between leukocyte telomere length and amyotrophic lateral sclerosis

We employed Mendelian randomization (MR) to evaluate the causal relationship between leukocyte telomere length (LTL) and amyotrophic lateral sclerosis (ALS) with summary statistics from genome-wide association studies (n = ~ 38,000 for LTL and ~ 81,000 for ALS in the European population; n = ~ 23,000 for LTL and ~ 4,100 for ALS in the Asian population). We further evaluated mediation roles of lipids in the pathway from LTL to ALS. The odds ratio per standard deviation decrease of LTL on ALS was 1.10 (95% CI 0.93–1.31, p = 0.274) in the European population and 0.75 (95% CI 0.53–1.07, p = 0.116) in the Asian population. This null association was also detected between LTL and frontotemporal dementia in the European population. However, we found that an indirect effect of LTL on ALS might be mediated by low density lipoprotein (LDL) or total cholesterol (TC) in the European population. These results were robust against extensive sensitivity analyses. Overall, our MR study did not support the direct causal association between LTL and the ALS risk in neither population, but provided suggestive evidence for the mediation role of LDL or TC on the influence of LTL and ALS in the European population.

Demographic and developmental patterns in telomere length across adolescence

Telomere length is often used in studies of adults as a biomarker of cellular aging and an indicator of stress exposure. However, we know little about how telomeres change over time, particularly over the course of the important developmental period of adolescence. We use data on telomere length collected at two points in time spanning adolescence (Years 9 and 15) from the Fragile Families and Child Wellbeing Study to examine longitudinal patterns (n = 1,654) in telomere length. We find a quantitatively small but significant average lengthening in telomere length across adolescence and little evidence of associations between telomere length and pubertal development.

Exome Sequencing Analysis Identifies Rare Variants in ATM and RPL8 That Are Associated With Shorter Telomere Length

Telomeres are important for maintaining genomic stability. Telomere length has been associated with aging, disease, and mortality and is highly heritable (∼82%). In this study, we aimed to identify rare genetic variants associated with telomere length using whole-exome sequence data. We studied 1,303 participants of the Erasmus Rucphen Family (ERF) study, 1,259 of the Rotterdam Study (RS), and 674 of the British Heart Foundation Family Heart Study (BHF-FHS). We conducted two analyses, first we analyzed the family-based ERF study and used the RS and BHF-FHS for replication. Second, we combined the summary data of the three studies in a meta-analysis. Telomere length was measured by quantitative polymerase chain reaction in blood. We identified nine rare variants significantly associated with telomere length (p-value < 1.42 × 10^–7, minor allele frequency of 0.2–0.5%) in the ERF study. Eight of these variants (in C11orf65, ACAT1, NPAT, ATM, KDELC2, and EXPH5) were located on chromosome 11q22.3 that contains ATM, a gene involved in telomere maintenance. Although we were unable to replicate the variants in the RS and BHF-FHS (p-value ≥ 0.21), segregation analysis showed that all variants segregate with shorter telomere length in a family. In the meta-analysis of all studies, a nominally significant association with LTL was observed with a rare variant in RPL8 (p-value = 1.48 × 10⁻⁶), which has previously been associated with age. Additionally, a novel rare variant in the known RTEL1 locus showed suggestive evidence for association (p-value = 1.18 × 10^–4) with LTL. To conclude, we identified novel rare variants associated with telomere length. Larger samples size are needed to confirm these findings and to identify additional variants.

Telomere length associations with cognition depend on Alzheimer's disease biomarkers

Introduction

While telomere shortening, a marker of cellular aging, may impact the progression of age-related neurodegenerative diseases, its association with cognition is unclear, particularly in the context of Alzheimer's disease (AD) pathology.

Methods

Telomere, cognitive, and CSF data from 482 participants in the AD Neuroimaging Initiative (148 cognitively normal, 283 mild cognitive impairment, 51 AD) was leveraged to assess telomere length associations with cognition (measured by memory and executive function) and interactions with CSF amyloid-β, tau, and APOE -ε4. Secondary analyses assessed brain volume and thickness outcomes.

Results

Longer telomeres at baseline were associated with faster executive function decline. Amyloid-β and tau interacted with telomere length on cognition, with longer telomeres related to faster decline among biomarker-positive individuals.

Discussion

Telomere associations with cognition shift with AD progression, with longer telomeres related to worse outcomes as pathology increases, highlighting the need for further investigation of telomere length along the AD neuropathological cascade.

Longitudinal changes in leukocyte telomere length and mortality in elderly Swedish men

Telomere length (TL) is considered an indicator of aging and age-related diseases, but longitudinal studies on TL changes and mortality are few. We therefore analyzed TL and longitudinal changes in TL in relation to all-cause, cardiovascular, and cancer mortality in 247 elderly Swedish men. TL was determined by the qPCR method at ages 71 and 81 and subsequent mortality cases were identified from the Swedish cause-of-death registry. Cox proportional hazard ratios were calculated during a mean follow-up of 7.4 years, during which 178 deaths occurred. Short telomeres at baseline was strongly associated with mortality risks, with a 40 to 70% increased risk of all-cause mortality, and a 2-fold increased risk of cancer mortality. Longitudinal changes in TL revealed shortening in 83% of individuals, whilst 10% extended their telomeres. TL attrition did not predict all-cause or cancer mortality, but we found a 60% decreased risk for cardiovascular mortality in those who shortened their telomeres. Our data show an increased risk of mortality in individuals with short baseline telomeres, but no relations to all-cause, and cancer mortality for changes in TL. Intriguingly, our data indicate lower risk of cardiovascular mortality with shortening of telomeres. The latter should be interpreted cautiously.

The Genetic Architecture of Bovine Telomere Length in Early Life and Association With Animal Fitness

Health and survival are key goals for selective breeding in farm animals. Progress, however, is often limited by the low heritability of these animal fitness traits in addition to measurement difficulties. In this respect, relevant early-life biomarkers may be useful for breeding purposes. Telomere length (TL), measured in leukocytes, is a good candidate biomarker since TL has been associated with health, ageing, and stress in humans and other species. However, telomere studies are very limited in farm animals. Here, we examined the genetic background, genomic architecture, and factors affecting bovine TL measurements in early life, and the association of the latter with animal fitness traits expressed later in life associated with survival, longevity, health, and reproduction. We studied two TL measurements, one at birth (TLB) and another during the first lactation (TLFL) of a cow. We performed a genome-wide association study of dairy cattle TL, the first in a non-human species, and found that TLB and TLFL are complex, polygenic, moderately heritable, and highly correlated traits. However, genomic associations with distinct chromosomal regions were identified for the two traits suggesting that their genomic architecture is not identical. This is reflected in changes in TL throughout an individual’s life. TLB had a significant association with survival, length of productive life and future health status of the animal, and could be potentially used as an early-life biomarker for disease predisposition and longevity in dairy cattle.

Chromosomal stability in buccal cells was linked to age but not affected by exercise and nutrients - Vienna Active Ageing Study (VAAS), a randomized controlled trial

The purpose of this study was to investigate the effect of six months strength training with or without supplementing protein and vitamins, on chromosomal integrity of buccal cells in institutionalized elderly.

One hundred seventeen women and men (65–98 years) performed either resistance training (RT), RT combined with a nutritional supplement (RTS) or cognitive training (CT) twice per week for six months. Participants’ fitness was measured using the 6 min walking, the chair rise, and the handgrip strength test. Genotoxicity and cytotoxicity parameters were investigated with the Buccal Micronucleus Cytome (BMcyt) assay.

Six minutes walking and chair rise performance improved significantly, however, no changes of the parameters of the BMcyt were detected. Age and micronuclei (MN) frequency correlated significantly, for both women (r = 0.597, p = 0.000) and men (r = 0.508, p = 0.000). Squared regressions revealed a significant increase in the MN frequency of buccal cells with age (R² = 0.466, p = 0.000).

Interestingly and contrary to what was shown in blood lymphocytes, chromosomal damage in buccal cells increases until very old age, which might qualify them as a valid biomarker for aging. Unexpectedly, in this group of institutionalized elderly, resistance training using elastic bands had no effect on chromosomal damage in buccal cells.

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Mutation in buccal cells increased until very old age – a new aging biomarker?

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Chromosomal damage in buccal cells was age-dependent and equal for women and men.

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Strength training improved fitness but not mutagenicity in buccal cells of elderly.

Telomere length and cognitive function: Differential patterns across sociodemographic groups

OBJECTIVE

The present study investigates whether associations between telomere length (TL) and cognitive performance across multiple domains are moderated by poverty status and race.

METHOD

Participants were 325 African American and White urban-dwelling adults (M age = 47.9 years; 49.5% African American; 50.2% female; 48.9% living in poverty) from the Healthy Aging in Neighborhoods of Diversity across the Life Span study. TL was assayed from peripheral blood mononuclear cells using quantitative polymerase chain reactions. Multivariable regression analyses examined interactions of TL, poverty status, and race with performance on the following cognitive tests: Trail-Making Test Parts A and B, Digit Span Forward and Backward, semantic verbal fluency, Brief Test of Attention, Benton Visual Retention Test (BVRT), and California Verbal Learning Test-II total learning, short-delay free recall, and long-delay free recall scores. Analyses adjusted for age, sex, and high school-or-greater educational attainment.

RESULTS

Significant three-way interactions of TL × Poverty Status × Race revealed that, among White participants living in poverty, shorter TL was associated with worse performance on Digit Span Forward and Backward (ps<.05). Additionally, significant two-way interactions of TL × Poverty Status revealed that, among all participants living in poverty, shorter TL was associated with worse performance on the Trail-Making Test Part B and the BVRT (ps<.05).

CONCLUSIONS

TL may be differentially associated with aspects of attention, executive functioning, and memory among individuals living in poverty, who may be uniquely vulnerable to adverse effects of shorter telomeres. Replication of these findings is needed to determine their generalizability. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Minimal Shortening of Leukocyte Telomere Length Across Age Groups in a Cross-Sectional Study for Carriers of a Longevity-Associated FOXO3 Allele

FOXO3 is one of the most prominent genes demonstrating a consistently reproducible genetic association with human longevity. The mechanisms by which these individual gene variants confer greater organismal lifespan are not well understood. We assessed the effect of longevity-associated FOXO3 alleles on age-related leukocyte telomere dynamics in a cross-sectional study comprised of samples from 121 healthy Okinawan-Japanese donors aged 21-95 years. We found that telomere length for carriers of the longevity associated allele of FOXO3 single nucleotide polymorphism rs2802292 displayed no significant correlation with age, an effect that was most pronounced in older (>50 years of age) participants. This is the first validated longevity gene variant identified to date showing an association with negligible loss of telomere length with age in humans in a cross-sectional study. Reduced telomere attrition may be a key mechanism for the longevity-promoting effect of the FOXO3 genotype studied.

Association of Short-term Change in Leukocyte Telomere Length With Cortical Thickness and Outcomes of Mental Training Among Healthy Adults: A Randomized Clinical Trial

Importance

Telomere length is associated with the development of age-related diseases and structural differences in multiple brain regions. It remains unclear, however, whether change in telomere length is linked to brain structure change, and to what extent telomere length can be influenced through mental training.

Objectives

To assess the dynamic associations between leukocyte telomere length (LTL) and cortical thickness (CT), and to determine whether LTL is affected by a longitudinal contemplative mental training intervention.

Design, Setting, and Participants

An open-label efficacy trial of three 3-month mental training modules with healthy, meditation-naive adults was conducted. Data on LTL and CT were collected 4 times over 9 months between April 22, 2013, and March 31, 2015, as part of the ReSource Project. Data analysis was performed between September 23, 2016, and June 21, 2019. Of 1582 eligible individuals, 943 declined to participate; 362 were randomly selected for participation and assigned to training or retest control cohorts, with demographic characteristics matched. The retest control cohorts underwent all testing but no training. Intention-to-treat analysis was performed.

Interventions

Training cohort participants completed 3 modules cultivating interoception and attention (Presence), compassion (Affect), or perspective taking (Perspective).

Main Outcomes and Measures

Change in LTL and CT.

Results

Of the 362 individuals randomized, 30 participants dropped out before study initiation (initial sample, 332). Data were available for analysis of the training intervention in 298 participants (n = 222 training; n = 76 retest control) (175 women [58.7%]; mean [SD] age, 40.5 [9.3] years). The training modules had no effect on LTL. In 699 observations from all 298 participants, mean estimated changes in the relative ratios of telomere repeat copy number to single-copy gene (T/S) were for no training, 0.004 (95% CI, -0.010 to 0.018); Presence, -0.007 (95% CI, -0.025 to 0.011); Affect, -0.005 (95% CI, -0.019 to 0.010); and Perspective, -0.001 (95% CI, -0.017 to 0.016). Cortical thickness change data were analyzed in 167 observations from 67 retest control participants (37 women [55.2%], mean [SD] age, 39.6 [9.0] years). In this retest control cohort subsample, naturally occurring LTL change was related to CT change in the left precuneus extending to the posterior cingulate cortex (mean t161 = 3.22; P < .001; r = 0.246). At the individual participant level, leukocyte telomere shortening as well as lengthening were observed. Leukocyte telomere shortening was related to cortical thinning (t77 = 2.38; P = .01; r = 0.262), and leukocyte telomere lengthening was related to cortical thickening (t77 = 2.42; P = .009; r = 0.266). All analyses controlled for age, sex, and body mass index.

Conclusions and Relevance

The findings of this trial indicate an association between short-term change in LTL and concomitant change in plasticity of the left precuneus extending to the posterior cingulate cortex. This result contributes to the evidence that LTL changes more dynamically on the individual level than previously thought. Further studies are needed to determine potential long-term implications of such change in relation to cellular aging and the development of neurodegenerative disorders. No effect of contemplative mental training was noted in what may be, to date, the longest intervention with healthy adults.

Trial Registration

ClinicalTrials.gov identifier: NCT01833104.

Metabolomics reveals a link between homocysteine and lipid metabolism and leukocyte telomere length: the ENGAGE consortium

Telomere shortening has been associated with multiple age-related diseases such as cardiovascular disease, diabetes, and dementia. However, the biological mechanisms responsible for these associations remain largely unknown. In order to gain insight into the metabolic processes driving the association of leukocyte telomere length (LTL) with age-related diseases, we investigated the association between LTL and serum metabolite levels in 7,853 individuals from seven independent cohorts. LTL was determined by quantitative polymerase chain reaction and the levels of 131 serum metabolites were measured with mass spectrometry in biological samples from the same blood draw. With partial correlation analysis, we identified six metabolites that were significantly associated with LTL after adjustment for multiple testing: lysophosphatidylcholine acyl C17:0 (lysoPC a C17:0, p-value = 7.1 × 10⁻⁶), methionine (p-value = 9.2 × 10⁻⁵), tyrosine (p-value = 2.1 × 10⁻⁴), phosphatidylcholine diacyl C32:1 (PC aa C32:1, p-value = 2.4 × 10⁻⁴), hydroxypropionylcarnitine (C3-OH, p-value = 2.6 × 10⁻⁴), and phosphatidylcholine acyl-alkyl C38:4 (PC ae C38:4, p-value = 9.0 × 10⁻⁴). Pathway analysis showed that the three phosphatidylcholines and methionine are involved in homocysteine metabolism and we found supporting evidence for an association of lipid metabolism with LTL. In conclusion, we found longer LTL associated with higher levels of lysoPC a C17:0 and PC ae C38:4, and with lower levels of methionine, tyrosine, PC aa C32:1, and C3-OH. These metabolites have been implicated in inflammation, oxidative stress, homocysteine metabolism, and in cardiovascular disease and diabetes, two major drivers of morbidity and mortality.

The effect of maternal vitamin C intake on fetal telomere length

BACKGROUND

A telomere is a nucleoprotein structure that is located at the end of a chromosome. Reduced telomere length manifests as physical ailments such as the increased risk of age-related illnesses. These age-related illnesses include heart disease and failure. Telomere length has been studied extensively in adults; however, limited information exists regarding maternal dietary influences on fetal telomere length.

OBJECTIVES

The objective of this study is to investigate the relationship between maternal vitamin C intake and fetal telomere length.

METHODS

Data for this analysis were collected as part of a prospective cohort study that recruited pregnant women upon admission into labor and delivery. Umbilical cord serum was collected for 96 maternal-fetal dyads, and DNA analysis was performed using a quantitative polymerase chain reaction. The telomere to single copy gene ratio method was used to determine telomere length, and maternal vitamin C intake was measured using the Dietary History Questionnaire (DHQ). Statistical analysis was conducted using generalized linear modeling-based analyses.

RESULTS

The linear model indicates that maternal vitamin C intake (OR = 1.0032, 95%CI: 1.0014-1.0052, p ≤ .05) was positively associated with fetal telomere length. BMI (OR = 1.1096, 95%CI: 1.0619-1.1660, p ≤ .05) had a significant positive association with fetal telomere length while sodium intake was negatively associated with this outcome (OR = 0.9997, 95%CI: 0.9995-0.9998, p ≤ .05). Black ethnicity had a significant negative association with fetal telomere length (OR = 0.0186, 95%CI: 0.0031-0.0824, p ≤ .05).

CONCLUSIONS

Our study shows a positive association between maternal vitamin C intake and fetal telomere length. These findings may provide a method of understanding and preventing adult-onset disease and mortality through intrauterine reprograming.

Telomeres, Telomerase and Ageing

Telomeres are specialised structures at the end of linear chromosomes. They consist of tandem repeats of the hexanucleotide sequence TTAGGG, as well as a protein complex called shelterin. Together, they form a protective loop structure against chromosome fusion and degradation. Shortening or damage to telomeres and opening of the loop induce an uncapped state that triggers a DNA damage response resulting in senescence or apoptosis.Average telomere length, usually measured in human blood lymphocytes, was thought to be a biomarker for ageing, survival and mortality. However, it becomes obvious that regulation of telomere length is very complex and involves multiple processes. For example, the "end replication problem" during DNA replication as well as oxidative stress are responsible for the shortening of telomeres. In contrast, telomerase activity can potentially counteract telomere shortening when it is able to access and interact with telomeres. However, while highly active during development and in cancer cells, the enzyme is down-regulated in most human somatic cells with a few exceptions such as human lymphocytes. In addition, telomeres can be transcribed, and the transcription products called TERRA are involved in telomere length regulation.Thus, telomere length and their integrity are regulated at many different levels, and we only start to understand this process under conditions of increased oxidative stress, inflammation and during diseases as well as the ageing process.This chapter aims to describe our current state of knowledge on telomeres and telomerase and their regulation in order to better understand their role for the ageing process.

Successful aging, cognitive function, socioeconomic status, and leukocyte telomere length

In a rapidly greying world, the notion that some individuals maintain successful aging trajectories, viz. high physical, cognitive, emotional, and social functioning in older age, is increasingly germane. Biomarkers of such successful aging are increasingly sought. Leukocyte telomere length (LTL), an emerging yardstick of cellular aging that is influenced by but distinct from chronological age, may also be associated to successful aging. Furthermore, given that socio-economic status (SES) influences successful aging trajectories, socioeconomic status may also moderate the association between chronological age and LTL. The goals of this study are to examine 1) whether successful aging is associated with LTL; 2) whether successful aging accounts for age-related LTL and 3) whether SES moderates the effect of age on LTL. Singaporean Chinese (n = 353) aged 65-80 completed a multidimensional assessment of successful aging and provided blood samples for LTL analysis. Results show that LTL negatively correlates with chronological age and positively correlates with successful aging. Successful aging mediates the association between chronological age and LTL. Moderated mediation analyses show that lower SES is associated with stronger negative associations of chronological age with successful aging and LTL. Moreover, the cognitive functioning dimension of successful aging is uniquely associated with LTL and its association with chronological age is moderated by SES. This study provides evidence that among older Singaporean Chinese with lower SES, declines in successful aging and in cognitive functioning are linked to age-related LTL shortening and hence to accelerated aging at the cellular level.

Stress and immunosenescence: The role of telomerase

Chronic stress is associated with the accelerated aging of the immune system and represents a potent risk factor for the development and progression of a wide range of physical and mental disorders. The elucidation of molecular pathways and mechanisms underlying the link between stress and cellular aging is an area of considerable interest and investigation. In this context, telomere biology has emerged as a particularly attractive candidate mechanism. Several studies have linked immune cell telomere length with stress-related conditions and states, and also with several physical and mental disorders. Because the cellular reverse transcriptase enzyme telomerase is the primary regulator of telomere length (by adding telomeric DNA to telomeres and thereby attenuating telomere shortening), the understanding of its regulation and regulatory functions constitutes a prime target for developing strategies to prevent, attenuate or reverse the adverse consequences of immune system aging (immunosenescence). In this review we provide an overview of the mechanistic pathways linking telomerase with stress and cellular aging, with an emphasis on the immune system. We summarize and synthesize the current state of the literature on immune cell telomerase in different stress- and aging-related disease states and provide recommendations for future research directions.

Telomere Biology and Human Phenotype

Telomeres are nucleoprotein structures that cap the end of each chromosome arm and function to maintain genome stability. The length of telomeres is known to shorten with each cell division and it is well-established that telomere attrition is related to replicative capacity in vitro. Moreover, telomere loss is also correlated with the process of aging in vivo. In this review, we discuss the mechanisms that lead to telomere shortening and summarise telomere homeostasis in humans throughout a lifetime. In addition, we discuss the available evidence that shows that telomere shortening is related to human aging and the onset of age-related disease.

Exploring the Causal Pathway From Telomere Length to Alzheimer's Disease: An Update Mendelian Randomization Study

Increasing evidence shows that telomere length shortening is associated with the risk for Alzheimer's disease (AD), pointing to a potential modifiable target for prevention. However, the causality of this association is still not clear. To investigate the causal relationship between telomere length and AD, we use two-sample Mendelian randomization (MR) to assess potential causal inference. We used summary-level data for telomere length (9,190 participants) and AD (71,880 cases and 383,378 controls). We performed two-sample MR analysis with single nucleotide polymorphisms previously identified to be associated with telomere length. The MR analyses were conducted using the inverse-variance-weighted method and complemented with the maximum likelihood, weighted median, weighted mode approaches. MR evidence suggested that shorter telomere length was causally associated with a higher risk for AD (inverse-variance weighted estimate of odds ratio (OR): 1.03 per SD decrease of telomere length, P=1.21×10^-2). The maximum likelihood, weighted median, weighted mode yielded a similar pattern of effects. The results were similar in sensitivity analyses. Using genetic instruments identified from large-scale genome-wide association study, robust evidence supports a causal role of telomere length shortening with increased risk of AD.

Neurocognitive Impairment and Associated Genetic Aspects in HIV Infection

HIV enters the central nervous system (CNS) early after infection. HIV-associated neurocognitive disorders (HAND) remain a serious complication of HIV infection despite available antiretroviral therapy (ART). Neurocognitive deficits observed in HAND are heterogeneous, suggesting a variability in individuals' susceptibility or resiliency to the detrimental CNS effects of HIV infection. This chapter reviews primary host genomic changes (immune-related genes, genes implicated in cognitive changes in primary neurodegenerative diseases), epigenetic mechanisms, and genetic interactions with ART implicated in HIV progression or HAND/neurocognitive complications of HIV. Limitations of the current findings include diversity of the HAND phenotype and limited replication of findings across cohorts. Strategies to improve the precision of future (epi)genetic studies of neurocognitive consequences of HIV infection are offered.

Telomere Length and All-Cause Mortality: A Meta-analysis

Telomere attrition is associated with increased morbidity and mortality of various age-related diseases. Reports of association between telomere length (TL) and all-cause mortality remain inconsistent. In the present study, a meta-analysis was performed using published cohort studies and un-published data from the Swedish Twin Registry (STR). Twenty-five studies were included: four STR cohorts (12,083 individuals with 2517 deaths) and 21 published studies. In the STR studies, one standard deviation (SD) decrement of leukocyte TL corresponded to 13% increased all-cause mortality risk (95% confidence interval [CI]: 7%-19%); individuals in the shortest TL quarter had 44% higher hazard (95% CI: 27%-63%) than those in the longest quarter. Meta-analysis of all eligible studies (121,749 individuals with 21,763 deaths) revealed one SD TL decrement-associated hazard ratio of 1.09 (95% CI: 1.06-1.13); those in the shortest TL quarter had 26% higher hazard (95% CI: 15%-38%) compared to the longest quarter, although between-study heterogeneity was observed. Analyses stratified by age indicated that the hazard ratio was smaller in individuals over 80 years old. In summary, short telomeres are associated with increased all-cause mortality risk in the general population. However, TL measurement techniques and age at measurement contribute to the heterogeneity of effect estimation.

Biological and imaging predictors of cognitive impairment after stroke: a systematic review

BACKGROUND

Cognitive impairment is frequent after stroke, and several studies have suggested that biological and imaging characteristics present before stroke are associated with the development of post-stroke cognitive impairment.

OBJECTIVE

The aim of our study was to systematically review biological and imaging predictors of cognitive impairment after stroke.

METHOD

Studies were identified from bibliographic databases and reference lists, and were included if conducted in patients with acute stroke, with at least 30 patients, and a follow-up of at least 3 months. We included articles on potential biomarkers of cognitive impairment that pre-existed to stroke.

RESULTS

We identified 22,169 articles, including 20,349 with abstract. After analysis, 66 studies conducted in 42 cohorts met selection criteria. They included 30-9522 patients [median 170; interquartile range (IQR) 104-251] with a median follow-up of 12 months (IQR 3-36). All studies met quality criteria for description of the study population and standardization of biomarkers. Twenty-nine studies met all quality criteria. There was no convincing evidence that any biological marker may predict cognitive impairment. The most consistent predictors of cognitive impairment after stroke were global atrophy and medial temporal lobe atrophy.

CONCLUSION

Pre-existing cerebral atrophy is the most consistent predictor of cognitive impairment that can be identified in patients with an acute stroke.

Relative Telomere Length and Stroke Risk in a Chinese Han Population

This study aimed to further understand the role of relative telomere length (RTL) in susceptibility to stroke and investigate the association regulator of telomere elongation helicase 1 (RETL1) gene polymorphisms and RTL. RTL was measured using the real-time quantitative polymerase chain reaction (qPCR) from 300 stroke patients and 299 healthy controls. Genotyping was performed using the Sequenom MassARRAY platform. The results indicated that stroke patients had significantly shorter median RTL than controls (P < 0.001). Compared with the longer RTL (≥ 0.766), the shorter RTL (< 0.766) was significantly increased the risk of stroke (odds ratio [OR] = 8.44, 95% confidence interval [CI] 5.42-13.14, P < 0.001). The RTL was categorized into tertiles, we found that the shorter RTL (0.515-1.366) (OR = 16.27, 95% CI 7.72-34.29, P < 0.001) and lowest RTL (< 0.515) (OR = 30.63, 95% CI 14.27-65.75, P < 0.001) were significantly increased stroke risk compared with the highest RTL (> 1.366). Stratified analysis showed that the shorter RTL was also significantly increased the risk of stroke compared with the longer RTL in male, age < 60 years and ≥ 60 years, except the female participants. In addition, individuals with the genotypes AA (rs2297441) and GG (rs6089953) have shorter telomeres than the genotypes GG (P = 0.031) and AA (P = 0.032), respectively. Our results suggested that shorter RTL was associated with an increased risk of stroke. The association was found between the genotypes AA (rs2297441) and GG (rs6089953) and shorter RTL in case group. Further studies in larger sample size and biological functional assays are warranted to validate our findings.

Combined Impact of Telomere Length and Mitochondrial DNA Copy Number on Cognitive Function in Community-Dwelling Very Old Adults

BACKGROUND

This study was conducted to investigate the combined impact of telomere length and mitochondrial DNA (mtDNA) copy number on cognitive function in community-dwelling very old adults.

METHODS

In total, 186 subjects over 75 years participated in this study. Cognitive function was assessed using the Korean Mini-Mental State Examination, and leukocyte telomere length and mtDNA copy number were measured using real-time polymerase chain reaction methods.

RESULTS

Both the fourth quartile of telomere length and mtDNA copy number were associated with cognitive dysfunction with an adjusted odds ratio of 0.23 (95% confidence interval (CI), 0.10-0.75) and 0.18 (95% CI, 0.03-0.54), respectively. Participants in the high telomere length/high mtDNA copy number group were more likely to have cognitive dysfunction than participants in the low telomere/low mtDNA copy number group with an adjusted odds ratio of 0.19 (95% CI, 0.07-0.58).

CONCLUSION

Our results collectively suggest that the combination of telomere length and mtDNA copy number may be useful for monitoring cognitive decline in older adults.