Exploring the interplay of psychological and biological components of stress response and telomere length in the transition from middle age to late adulthood: A systematic review

Ageing and chronic stress have been linked to reduced telomere length (TL) in mixed-age groups. Whether stress response components are linked to TL during the midlife-to-late adulthood transition remains unclear. Our study aimed to synthesise evidence on the relationship between psychological and biological components of stress response on TL in middle-aged and older adults. We conducted a systematic review of studies obtained from six databases (PubMed, CINAHL, EMBASE, PsycINFO, Web of Science, and Scopus) and evaluated by two independent reviewers. Original research measuring psychological and biological components of stress response and TL in human individuals were included. From an initial pool of 614 studies, 15 were included (n = 9446 participants). Synthesis of evidence showed that higher psychological components of the stress response (i.e., global perceived stress or within a specific life domain and cognitive appraisal to social-evaluative stressors) were linked to shorter TL, specifically in women or under major life stressors. For the biological stress response, cortisol, dehydroepiandrosterone sulphate and IGF-1/cortisol imbalance, IL-6, MCP-1, blood pressure, and heart rate presented a significant association with TL, but this relationship depended on major life stressors and the stress context (manipulated vs. non-manipulated conditions). This comprehensive review showed that psychological and biological components of the stress response are linked to shorter TL, but mainly in women or those under a major life stressor and stress-induced conditions. The interaction between stressor attributes and psychological and biological reactions in the transition from middle to late adulthood still needs to be fully understood, and examining it is a critical step to expanding our understanding of stress's impact on ageing trajectories.

Associations Between Children's Telomere Length, Parental Intrusiveness, and the Development of Early Externalizing Behaviors

Shorter telomeres mark cellular aging and are linked to chronic stress exposure as well as negative physical and psychological outcomes. However, it is unclear whether telomere length mediates associations between early stress exposure and later externalizing problems, or whether boys and girls differ in pathways to these concerns. We therefore examined associations between telomere length, early stress via negative caregiving, and children's externalizing symptom development over time in 409 three-year-old children and their parents. Telomere length mediated the association between early parental intrusiveness and later rule-breaking behavior; however, this association was moderated by children's biological sex such that parent intrusiveness was related only to boys' rule-breaking. Findings support the notion that children's telomere length may mark individual differences in responses to negative early caregiving, and highlight a potential mechanism contributing to the development of rule-breaking problems in boys.

Association between Childhood Exposure to Family Violence and Telomere Length: A Meta-Analysis

The aims of this meta-analysis were to examine the association between childhood exposure to family violence and telomere length and the moderating variables that influence this association. Relevant works published on or before 1st September 2022 were identified through a search in five major databases in English and 19 articles (N = 18,977) finally met the inclusion criteria. A meta-analysis was conducted to compute the pooled effect size (correlation; r), and moderator analyses were performed using a random effects meta-analytic model. The studies yielded a significant inverse association between childhood exposure to family violence and telomere length, with a small effect size (r = -0.038, 95% CI [-0.070, -0.005], p = 0.025). Furthermore, the strength of this association was stronger in studies examining the co-occurrence of multiple types of violence than in those examining just one type (Q = 8.143, p = 0.004). These findings suggested that victims' telomere length may be negatively influenced by childhood exposure to family violence and that such impairment appears to be stronger for those who are exposed to multiple types of violence. Future studies are necessary to examine the moderating and mediating factors underlying the association between childhood exposure to family violence and telomere length.

Immune and Epigenetic Pathways Linking Childhood Adversity and Health Across the Lifespan

Childhood adversity is associated with a host of mental and physical health problems across the lifespan. Individuals who have experienced childhood adversity (e.g., child abuse and neglect, family conflict, poor parent/child relationships, low socioeconomic status or extreme poverty) are at a greater risk for morbidity and premature mortality than those not exposed to childhood adversity. Several mechanisms likely contribute to the relationship between childhood adversity and health across the lifespan (e.g., health behaviors, cardiovascular reactivity). In this paper, we review a large body of research within the field of psychoneuroimmunology, demonstrating the relationship between early life stress and alterations of the immune system. We first review the literature demonstrating that childhood adversity is associated with immune dysregulation across different indices, including proinflammatory cytokine production (and its impact on telomere length), illness and infection susceptibility, latent herpesvirus reactivation, and immune response to a tumor. We then summarize the growing literature on how childhood adversity may alter epigenetic processes. Finally, we propose future directions related to this work that have basic and applied implications.

The pediatric buccal epigenetic clock identifies significant ageing acceleration in children with internalizing disorder and maltreatment exposure

Background

Studies reporting accelerated ageing in children with affective disorders or maltreatment exposure have relied on algorithms for estimating epigenetic age derived from adult samples. These algorithms have limited validity for epigenetic age estimation during early development. We here use a pediatric buccal epigenetic (PedBE) clock to predict DNA methylation-based ageing deviation in children with and without internalizing disorder and assess the moderating effect of maltreatment exposure. We further conduct a gene set enrichment analysis to assess the contribution of glucocorticoid signaling to PedBE clock-based results.

Method

DNA was isolated from saliva of 158 children [73 girls, 85 boys; mean age (SD) = 4.25 (0.8) years] including children with internalizing disorder and maltreatment exposure. Epigenetic age was estimated based on DNA methylation across 94 CpGs of the PedBE clock. Residuals of epigenetic age regressed against chronological age were contrasted between children with and without internalizing disorder. Maltreatment was coded in 3 severity levels and entered in a moderation model. Genome-wide dexamethasone-responsive CpGs were derived from an independent sample and enrichment of these CpGs within the PedBE clock was identified.

Results

Children with internalizing disorder exhibited significant acceleration of epigenetic ageing as compared to children without internalizing disorder (F_1,147 = 6.67, p = .011). This association was significantly moderated by maltreatment severity (b = 0.49, 95% CI [0.073, 0.909], t = 2.322, p = .022). Children with internalizing disorder who had experienced maltreatment exhibited ageing acceleration relative to children with no internalizing disorder (1–2 categories: b = 0.50, 95% CI [0.170, 0.821], t = 3.008, p = .003; 3 or more categories: b = 0.99, 95% CI [0.380, 1.593], t = 3.215, p = .002). Children with internalizing disorder who were not exposed to maltreatment did not show epigenetic ageing acceleration. There was significant enrichment of dexamethasone-responsive CpGs within the PedBE clock (OR = 4.36, p = 1.65*10–6). Among the 94 CpGs of the PedBE clock, 18 (19%) were responsive to dexamethasone.

Conclusion

Using the novel PedBE clock, we show that internalizing disorder is associated with accelerated epigenetic ageing in early childhood. This association is moderated by maltreatment severity and may, in part, be driven by glucocorticoids. Identifying developmental drivers of accelerated epigenetic ageing after maltreatment will be critical to devise early targeted interventions.

Are Biological Consequences of Childhood Exposures Detectable in Telomere Length Decades Later?

Negative early-life exposures have been linked to a host of poor adult health outcomes, but are such early exposures associated with cellular senescence decades later? This study uses data from the Health and Retirement Study to examine the association between six childhood exposure domains (eg, socioeconomic disadvantage, risky parental behavior) and a biomarker of aging, telomere length, among 4,935 respondents. Telomere length is obtained from DNA of cells found in saliva and is measured as the telomere repeat copy number to single gene copy number ratio (T/S). Men who as children were exposed to risky parental behaviors or who reported risky adolescent behaviors have shorter telomeres (b = -0.031, p = .052; b = -0.041, p = .045, respectively); however, these relationships are attenuated after adjusting for adult risks and resources. Among women, parental substance abuse is associated with shorter telomeres even after adjusting for adult risks and resources (b = -0.041, p = .005). In addition, men and women whose mother lived at least until the age of 85 have longer telomeres than those without a long-lived mother (b = 0.021, p = .045; b = 0.032, p = .005, respectively). Taken together, the ways in which early-life exposures are associated with adult telomeres vary for men and women.

Telomere length and signal joint T-cell receptor rearrangement excision circles as biomarkers for chronological age estimation

BACKGROUND

Chronological age estimation is a challenging marker in the field of forensic medicine. The current study aimed to investigate the accuracy of signal joint T-cell receptor rearrangement excision circles (sjTRECs) quantification and telomere length measurement as methods for estimating chronological age.

METHODS

Telomere length was estimated in the DNA derived from the buccal cells through estimating the telomeric restriction fragment (TRF) length using TeloTTAGGG Telomere Length Assay while the sjTRECs quantification was carried out on DNA isolated from the blood samples using qPCR.

RESULTS

The TRF length was shortened with increased age (r = -0.722, p < 0.001). The sjTRECs were also decreased with increased age (r = -0.831, p < 0.001). Stronger coefficient and lower standard error of the estimate was obtained when multiple regression analysis for age prediction based on the values of both methods was applied (r = -0.876, p < 0.001).

Chronic psychosocial and financial burden accelerates 5-year telomere shortening: findings from the Coronary Artery Risk Development in Young Adults Study

Leukocyte telomere length, a marker of immune system function, is sensitive to exposures such as psychosocial stressors and health-maintaining behaviors. Past research has determined that stress experienced in adulthood is associated with shorter telomere length, but is limited to mostly cross-sectional reports. We test whether repeated reports of chronic psychosocial and financial burden is associated with telomere length change over a 5-year period (years 15 and 20) from 969 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) Study, a longitudinal, population-based cohort, ages 18-30 at time of recruitment in 1985. We further examine whether multisystem resiliency, comprised of social connections, health-maintaining behaviors, and psychological resources, mitigates the effects of repeated burden on telomere attrition over 5 years. Our results indicate that adults with high chronic burden do not show decreased telomere length over the 5-year period. However, these effects do vary by level of resiliency, as regression results revealed a significant interaction between chronic burden and multisystem resiliency. For individuals with high repeated chronic burden and low multisystem resiliency (1 SD below the mean), there was a significant 5-year shortening in telomere length, whereas no significant relationships between chronic burden and attrition were evident for those at moderate and higher levels of resiliency. These effects apply similarly across the three components of resiliency. Results imply that interventions should focus on establishing strong social connections, psychological resources, and health-maintaining behaviors when attempting to ameliorate stress-related decline in telomere length among at-risk individuals.

Psychosocial Stressors and Telomere Length: A Current Review of the Science

A growing literature suggests that exposure to adverse social conditions may accelerate biological aging, offering one mechanism through which adversity may increase risk for age-related disease. As one of the most extensively studied biological markers of aging, telomere length (TL) provides a valuable tool to understand potential influences of social adversity on the aging process. Indeed, a sizeable literature now links a wide range of stressors to TL across the life span. The aim of this article is to review and evaluate this extant literature with a focus on studies that investigate psychosocial stress exposures and experiences in early life and adulthood. We conclude by outlining potential biological and behavioral mechanisms through which psychosocial stress may influence TL, and we discuss directions for future research in this area.

Translating basic research knowledge on the biological embedding of early-life stress into novel approaches for the developmental programming of lifelong health

This review integrates scientific knowledge obtained over the past few decades on the biological mechanisms that contribute to the profound association between exposure to early adversity, including childhood trauma and prenatal stress, and the lifelong elevated risk to develop a broad range of diseases. We further discuss insights into gene-environment interactions moderating the association between early adversity and disease manifestation and we discuss the role of epigenetic and other molecular processes in the biological embedding of early adversity. Based on these findings, we propose potential mechanisms that may contribute to the intergenerational transmission of risk related to early adversity from the mother to the fetus. Finally, we argue that basic research knowledge on the biological embedding of early adversity must now be translated into novel intervention strategies that are mechanism-driven and sensitive to developmental timing. Indeed, to date, there are no diagnostic biomarkers of risk or mechanism-informed interventions that we can offer to victims of early adversity in order to efficiently prevent or reverse adverse health outcomes. Such translational efforts can be expected to have significant impact on both clinical practice and the public health system, and will promote precision medicine in pediatrics and across the lifespan.

Cumulative lifetime stress exposure and leukocyte telomere length attrition: The unique role of stressor duration and exposure timing

BACKGROUND

Stress exposure occurring across the lifespan increases risk for disease, potentially involving telomere length shortening. Stress exposure during childhood and adulthood has been cross-sectionally linked with shorter telomere length. However, few longitudinal studies have examined telomere length attrition over time, and none have investigated how stressor duration (acute life events vs. chronic difficulties), timing (childhood vs. adulthood), and perceived severity may be uniquely related to telomere length shortening.

METHODS

To address these issues, we administered a standardized instrument for assessing cumulative lifetime stress exposure (Stress and Adversity Inventory; STRAIN) to 175 mothers of children with Autism Spectrum Disorder or neurotypical children and measured their leukocyte telomere length (LTL) at baseline and 2 years later.

RESULTS

Greater count of lifetime stressors was associated with shorter LTL at baseline and greater LTL attrition over time. When separating lifetime stressors into acute life events and chronic difficulties, only greater count of chronic difficulties significantly predicted shorter baseline LTL and greater LTL attrition. Similarly, when examining timing of stressor exposure, only greater count of chronic childhood difficulties (age < 18) significantly predicted shorter baseline LTL and greater LTL attrition over the 2-year period in mid-life. Importantly, these results were robust while controlling for stressors occurring during the interim 2-year period. Post-hoc analyses suggested that chronic difficulties occurring during earlier childhood (0-12 years) were associated with greater LTL attrition. Cumulative stressor severity predicted LTL attrition in a parallel manner, but was less consistently associated with baseline LTL.

CONCLUSIONS

These data are the first to examine the effects of different aspects of cumulative lifetime stress exposure on LTL attrition over time, suggesting that accumulated chronic difficulties during childhood may play a unique role in shaping telomere shortening in midlife.

The relation of telomere length at midlife to subsequent 20-year depression trajectories among women

BACKGROUND

Telomeres cap and protect DNA but shorten with each somatic cell division. Aging and environmental and lifestyle factors contribute to the speed of telomere attrition. Current evidence suggests a link between relative telomere length (RTL) and depression but the directionality of the relationship remains unclear. We prospectively examined associations between RTL and subsequent depressive symptom trajectories.

METHODS

Among 8,801 women of the Nurses' Health Study, depressive symptoms were measured every 4 years from 1992 to 2012; group-based trajectories of symptoms were identified using latent class growth-curve analysis. Multinomial logistic models were used to relate midlife RTLs to the probabilities of assignment to subsequent depressive symptom trajectory groups.

RESULTS

We identified four depressive symptom trajectory groups: minimal depressive symptoms (62%), worsening depressive symptoms (14%), improving depressive symptoms (19%), and persistent-severe depressive symptoms (5%). Longer midlife RTLs were related to significantly lower odds of being in the worsening symptoms trajectory versus minimal trajectory but not to other trajectories. In comparison with being in the minimal symptoms group, the multivariable-adjusted odds ratio of being in the worsening depressive symptoms group was 0.78 (95% confidence interval, 0.62-0.97; p = 0.02), for every standard deviation increase in baseline RTL.

CONCLUSIONS

In this large prospective study of generally healthy women, longer telomeres at midlife were associated with significantly lower risk of a subsequent trajectory of worsening mood symptoms over 20 years. The results raise the possibility of telomere shortening as a novel contributing factor to late-life depression.

Adverse Childhood Experiences and Telomere Length a Look Into the Heterogeneity of Findings-A Narrative Review

Background: Adverse childhood experiences (ACEs) have been associated with poor mental and somatic health. Accumulating evidence indicates that accelerated biological aging-indexed by altered telomere-related markers-may contribute to associations between ACEs and negative long-term health outcomes. Telomeres are repeated, non-coding deoxyribonucleic acid (DNA) sequences at the end of chromosomes. Telomeres shorten during repeated cell divisions over time and are being used as a marker of biological aging. Objectives: The aim of the current paper is to review the literature on the relationship between ACEs and telomere length (TL), with a specific focus on how the heterogeneity of sample and ACEs characteristics lead to varying associations between ACEs and TL. Methods: Multiple databases were searched for relevant English peer-reviewed articles. Thirty-eight papers were found to be eligible for inclusion in the current review. Results: Overall, the studies indicated a negative association between ACEs and TL, although many papers presented mixed findings and about a quarter of eligible studies found no association. Studies with smaller sample sizes more often reported significant associations than studies with larger samples. Also, studies reporting on non-clinical and younger samples more often found associations between ACEs and TL compared to studies with clinical and older samples. Reviewing the included studies based on the "Stressor Exposure Characteristics" recently proposed by Epel et al. (2018) revealed a lack of detailed information regarding ACEs characteristics in many studies. Conclusion: Overall, it is difficult to achieve firm conclusions about associations of ACEs with TL due to the heterogeneity of study and ACE characteristics and the heterogeneity in reported findings. The field would benefit from more detailed descriptions of study samples and measurement of ACEs.

Telomere length and socioeconomic status at neighborhood and individual levels among 80,000 adults in the Genetic Epidemiology Research on Adult Health and Aging cohort

Background

Telomere length (TL) may serve as a biologic marker of aging. We examined neighborhood and individual-level socioeconomic status (SES) in relation to TL.

Methods

The study included 84,996 non-Hispanic white subjects from the Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort, part of the Research Program on Genes, Environment and Health. Relative TL (T/S) was log₂ transformed to improve normality and standardized to have mean 0 and variance 1. Neighborhood SES was measured using the Neighborhood Deprivation Index (NDI), and individual SES was measured by self-reported education level. We fit linear regression models of TL on age, sex, smoking, body mass index, comorbidities, NDI, and education level. We tested for differences in the associations by sex and nonlinearity in the association of NDI with TL.

Results

Each SD increase in NDI was associated with a decrease of 0.0192 in standardized TL, 95% confidence interval (CI) = -0.0306, -0.0078. There was no evidence of nonlinearity in the association of NDI with TL. We further found that less than high school education was associated with a decrease of 0.1371 in standardized TL, 95% CI = -0.1919, -0.0823 as compared to a college education. There were no differences in the associations by sex.

Conclusions

We found evidence that both lower neighborhood SES and lower individual-level SES are associated with shorter TL among non-Hispanic whites. Our findings suggest that socioeconomic factors may influence aging by contributing to shorter TL.

Cold parenting is associated with cellular aging in offspring: A retrospective study

BACKGROUND

Early life stress is a known risk factor for diseases and premature death. We tested whether parenting style impacts telomere length (TL), a cellular aging biomarker.

METHODS

Information on parents' style of parenting was obtained from 199 participants in the Adventist Health Study-1 (AHS-1) who 27+ years later also enrolled in the AHS-2 where blood was collected for relative TL (rTL) assessment.

RESULTS

Subjects describing their mothers' parenting style as cold had on average 25% smaller rTL compared to subjects not reporting a cold mother (1.89 vs 2.53). This association was greatest among those with less education, and those who stayed overweight/obese or put on weight during follow-up.

CONCLUSIONS

These results support previous findings that early life stress may have health implications by promoting cellular aging, and expands these stressors to include cold parenting during an individuals' formative years. Higher education and normal weight seem to provide some resilience.

Association between internet gaming addiction and leukocyte telomere length in Korean male adolescents

Internet gaming addiction (IGA) has been associated with many negative health outcomes, especially for youth. In particular, the potential association between IGA and leukocyte telomere length (LTL) has yet to be examined. In this study we compared LTL in Korean male adolescents with and without IGA and examined the association between LTL and autonomic functions. Specifically, plasma catecholamine, serum cortisol, and psychological stress levels were measured as autonomic functions. Data were collected using participant blood samples analyzed for LTL, catecholamine, and cortisol levels and a set of questionnaires to assess IGA and psychological stress levels of the participants. The LTL measurements were made using a qPCR-based technique, and the relative LTL was calculated as the telomere/single copy (T/S) ratio. T/S ratio was significantly shorter in the IGA group than in the non-IGA group (150.43 ± 6.20 and 187.23 ± 6.42, respectively; p < .001) after adjusting for age. In a univariate regression analysis, age, daily Internet gaming time, IGA score, and catecholamine level (epinephrine and norepinephrine) were significantly associated with T/S ratio. However, duration of Internet gaming exposure, dopamine, cortisol, and psychological stress levels were not found to be associated with T/S ratio. In the final multiple linear regression model, age, daily Internet gaming time, and epinephrine level showed statistically significant relationships with T/S ratio. Our results indicate that in addition to age, involvement in excessive Internet gaming may induce LTL shortening in male adolescents, which may be partially attributable to changes in autonomic function such as catecholamine level. These findings further understanding of the health effects of IGA and highlight the need for screening and intervention strategies for male adolescents with IGA.

A scoping systematic review of social stressors and various measures of telomere length across the life course

Numerous studies examine the relationship between social stressors and telomere length (TL). Beyond considering methods and major findings, this scoping systematic review takes a novel approach as it groups studies according to the types of social stressor considered and by age groups. Following PRISMA guidelines, we searched PubMed, Web of Science, Embase, and Scopus. We included all English-language human subject research articles that modeled any measure of TL as a dependent variable and exposure to a social stressor as an independent variable. For the sample of 105 articles, we summarized methods and findings by type of social stressor (socioeconomic stressors, stressful life events, work-related stressors, and neighborhood stressors) and by age of the study population (infants/children, middle-aged adults, older adults, and mixed samples of middle-aged and older adults). We found more variation in TL measurement methodology in studies of infants/children and older adults than in studies focusing on middle-aged adults. The most consistent finding was a relationship between early-life stressors and shorter TL. Work and neighborhood stressors, and older populations, are currently understudied. Across all stressors, limited evidence suggests that the stress-TL relationship may be moderated by characteristics such as age, sex, and race/ethnicity. We conclude with specific suggestions for future research.

The Emerging Roles for Telomerase in the Central Nervous System

Telomerase, a specialized ribonucleoprotein enzyme complex, maintains telomere length at the 3′ end of chromosomes, and functions importantly in stem cells, cancer and aging. Telomerase exists in neural stem cells (NSCs) and neural progenitor cells (NPCs), at a high level in the developing and adult brains of humans and rodents. Increasing studies have demonstrated that telomerase in NSCs/NPCs plays important roles in cell proliferation, neuronal differentiation, neuronal survival and neuritogenesis. In addition, recent works have shown that telomerase reverse transcriptase (TERT) can protect newborn neurons from apoptosis and excitotoxicity. However, to date, the link between telomerase and diseases in the central nervous system (CNS) is not well reviewed. Here, we analyze the evidence and summarize the important roles of telomerase in the CNS. Understanding the roles of telomerase in the nervous system is not only important to gain further insight into the process of the neural cell life cycle but would also provide novel therapeutic applications in CNS diseases such as neurodegenerative condition, mood disorders, aging and other ailments.

Early life adversity and telomere length: a meta-analysis

Early adversity, in the form of abuse, neglect, socioeconomic status and other adverse experiences, is associated with poor physical and mental health outcomes. To understand the biologic mechanisms underlying these associations, studies have evaluated the relationship between early adversity and telomere length, a marker of cellular senescence. Such results have varied in regard to the size and significance of this relationship. Using meta-analytic techniques, we aimed to clarify the relationship between early adversity and telomere length while exploring factors affecting the association, including adversity type, timing and study design. A comprehensive search in July 2016 of PubMed/MEDLINE, PsycINFO and Web of Science identified 2462 studies. Multiple reviewers appraised studies for inclusion or exclusion using a priori criteria; 3.9% met inclusion criteria. Data were extracted into a structured form; the Newcastle-Ottawa Scale assessed study quality, validity and bias. Forty-one studies (N=30 773) met inclusion criteria. Early adversity and telomere length were significantly associated (Cohen's d effect size=-0.35; 95% CI, -0.46 to -0.24; P<0.0001). Sensitivity analyses revealed no outlier effects. Adversity type and timing significantly impacted the association with telomere length (P<0.0001 and P=0.0025, respectively). Subgroup and meta-regression analyses revealed that medication use, medical or psychiatric conditions, case-control vs longitudinal study design, methodological factors, age and smoking significantly affected the relationship. Comprehensive evaluations of adversity demonstrated more extensive telomere length changes. These results suggest that early adversity may have long-lasting physiological consequences contributing to disease risk and biological aging.

The fetal programming of telomere biology hypothesis: an update

Research on mechanisms underlying fetal programming of health and disease risk has focused primarily on processes that are specific to cell types, organs or phenotypes of interest. However, the observation that developmental conditions concomitantly influence a diverse set of phenotypes, the majority of which are implicated in age-related disorders, raises the possibility that such developmental conditions may additionally exert effects via a common underlying mechanism that involves cellular/molecular ageing-related processes. In this context, we submit that telomere biology represents a process of particular interest in humans because, firstly, this system represents among the most salient antecedent cellular phenotypes for common age-related disorders; secondly, its initial (newborn) setting appears to be particularly important for its long-term effects; and thirdly, its initial setting appears to be plastic and under developmental regulation. We propose that the effects of suboptimal intrauterine conditions on the initial setting of telomere length and telomerase expression/activity capacity may be mediated by the programming actions of stress-related maternal-placental-fetal oxidative, immune, endocrine and metabolic pathways in a manner that may ultimately accelerate cellular dysfunction, ageing and disease susceptibility over the lifespan. This perspectives paper provides an overview of each of the elements underlying this hypothesis, with an emphasis on recent developments, findings and future directions.This article is part of the theme issue 'Understanding diversity in telomere dynamics'.

Air Pollution Stress and the Aging Phenotype: The Telomere Connection

Aging is a complex physiological phenomenon. The question why some subjects grow old while remaining free from disease whereas others prematurely die remains largely unanswered. We focus here on the role of air pollution in biological aging. Hallmarks of aging can be grouped into three main categories: genomic instability, telomere attrition, and epigenetic alterations leading to altered mitochondrial function and cellular senescence. At birth, the initial telomere length of a person is largely determined by environmental factors. Telomere length shortens with each cell division and exposure to air pollution as well as low residential greens space exposure is associated with shorter telomere length. Recent studies show that the estimated effects of particulate air pollution exposure on the telomere mitochondrial axis of aging may play an important role in chronic health effects of air pollution. The exposome encompasses all exposures over an entire life. As telomeres can be considered as the cellular memories of exposure to oxidative stress and inflammation, telomere maintenance may be a proxy for assessing the "exposome". If telomeres are causally related to the aging phenotype and environmental air pollution is an important determinant of telomere length, this might provide new avenues for future preventive strategies.

The potential impact of biochemical mediators on telomere attrition in major depressive disorder and implications for future study designs: A narrative review

BACKGROUND

Major depressive disorder (MDD) has been proposed to represent a "disease of premature aging", which is associated with certain biomarkers of cellular ageing and numerous other age-related diseases. Over the last decade, telomere length (TL) arose as a surrogate for cellular aging. Recent data suggests that TL might be reduced in patients with MDD, however, results are still inconclusive. This might be explained by the lack of assessment of potential biochemical mediators that are directly associated with telomere shortening and frequently observed in patients with MDD.

METHODS

A narrative review was performed. The PubMed database was searched for relevant studies.

RESULTS

We identified four major mediators, which are recurrently reported in patients with MDD and are associated with reduced TL: inflammation/oxidative stress, dysregulation of the hypothalamic-pituitary-adrenal axis, metabolic dysbalance including insulin resistance, and decreased brain-derived neurotrophic factor. These mediators are also mutually associated and were not systematically assessed in current studies investigating TL and MDD, which might explain inconclusive findings across current literature. Finally, we discuss possible ways to assess those mediators and potential implications of such approaches for future research.

LIMITATIONS

The majority of identified studies had cross-sectional designs and used heterogeneous methods to assess TL and associated relevant biochemical mediators.

CONCLUSIONS

A better understanding of the complex interactions between biochemical mediators, somatic comorbidities and shortened telomeres in patients with MDD might further specify the pathophysiology-based conceptualization and, based on that, personalized treatment of MDD.

Association between childhood trauma and accelerated telomere erosion in adulthood: A meta-analytic study

BACKGROUND

Childhood trauma has long-term sequelae on health status and contributes to numbers of somatic and mental disorders in later life. Findings from experimental studies in animals suggest that telomere erosion may be a mediator of this relationship. However, results from human studies are heterogeneous. To address these inconsistencies, we performed a meta-analysis regarding the association between childhood trauma and telomere length in adulthood.

METHOD

Articles were identified by systematically searching the Medline, EMBASE and Web of Science databases. Twenty four studies, which include twenty six sample sets and 30,919 participants, met the inclusion criteria for meta-analyses.

RESULTS

This meta-analyses revealed that individuals experienced childhood trauma have accelerated telomere erosion in adulthood, with a small effect size (r = -0.05, 95% CI = -0.08-0.03, p < 0.001). Subgroup analyses by type of childhood trauma revealed a trend in difference between groups (Q = 5.24, p = 0.07). Analyses for individual trauma types revealed a significant association between childhood separation and telomere erosion (r = -0.09, p < 0.001), but not for physical abuse, sexual abuse and loss of a parent.

CONCLUSION

This meta-analysis demonstrated a significant association between childhood trauma and accelerated telomere erosion in adulthood, and further revealed that different trauma types have various impacts on telomere. Additional research on the mechanism that links the individual types of childhood trauma with telomere is needed in the future.

The effects of early life adversity on the immune system

Early life adversity (ELA) is associated with a higher risk for diseases in adulthood. Although the pathophysiological effects of ELA are varied, there may be a unifying role for the immune system in all of the long-term pathologies such as chronic inflammatory disorders (autoimmune diseases, allergy, and asthma). Recently, significant efforts have been made to elucidate the long-term effects ELA has on immune function, as well as the mechanisms underlying these immune changes. In this review, we focus on data from human studies investigating immune parameters in relation to post-natal adverse experiences. We describe the current understanding of the 'ELA immune phenotype', characterized by inflammation, impairment of the cellular immune system, and immunosenescence. However, at present, data addressing specific immune functions are limited and there is a need for high-quality, well powered, longitudinal studies to unravel cause from effect. Besides the immune system, also the stress system and health behaviors are altered in ELA. We discuss probable underlying mechanisms based on epigenetic programming that could explain the ELA immune phenotype and whether this is a direct effect of immune programming or an indirect consequence of changes in behavior or stress reactivity. Understanding the underlying mechanisms will help define effective strategies to prevent or counteract negative ELA-associated outcomes.

The Relationship Between Childhood Psychosocial Stressor Level and Telomere Length: A Meta-Analysis

This meta-analysis examined the association between the level of childhood psychosocial stressors and telomere length, an important health biomarker. The meta-analysis, including 27 samples and 16,238 participants, found a significant association of -0.08 between a higher level of childhood stressors and shorter telomere length at a mean age of 42 across studies. Moderator analyses showed a trend in the direction of effect sizes being significantly larger with shorter times between the stressors and telomere measurement. Moderator analyses showed significantly higher effect sizes for studies that used a categorical method for assessing child stressor level and for assays completed with qPCR rather than with the Southern blot method. There was no significant moderation of effect size by whether study assayed leukocytes or buccal cells, whether the study assessed child stressor level by memory-based recall versus archival records, and whether the study controlled for age, sex, or additional variables. The results, focused on childhood events, add to prior findings that perceived stress and negative emotions are associated with telomere length.

A meta-analysis of the relationship between anxiety and telomere length

BACKGROUND AND OBJECTIVES

Telomeres are protective caps at the ends of chromosomes, and shorter telomeres are associated with poor physical health. The present study set out to consolidate the varying effect sizes found so far in studies of anxiety and telomere length.

DESIGN AND METHODS

A meta-analytic investigation of the relationship between anxiety and telomere length used information from 17 different samples comprising a total of 19,424 participants.

RESULTS

The results showed a small but significant association, r = -.06, between higher anxiety and shorter telomeres. Studies comparing individuals diagnosed with an anxiety disorder with other individuals had a significant effect size, and studies that did not use this comparison threshold did not have a significant effect size.

CONCLUSIONS

Anxiety is associated with an important biomarker related to health. Future experimental studies that examine the impact of interventions intended to reduce anxiety in conjunction with measurement of telomere length can further clarify the impact of anxiety on telomere length.

Stressful life events and leucocyte telomere length: Do lifestyle factors, somatic and mental health, or low grade inflammation mediate this relationship? Results from a cohort of Danish men born in 1953

Exposure to psychosocial stress is associated with increased risk of a number of somatic and mental disorders with relation to immune system functioning. We aimed to explore whether stressful events in early and recent life was associated with leucocyte telomere length (TL), which is assumed to reflect the accumulated burden of inflammation and oxidative stress occurring during the life course. We specifically aimed to address whether childhood constitutes a sensitive period and how much of the relation between stressful life events and TL is mediated through somatic and mental health, lifestyle, and markers of low-grade inflammation. A cohort of Danish men born in 1953 has been followed since birth in the Metropolit Cohort. These men underwent a health examination including blood sampling in 2010 and a subset of 324 also had a quantitative PCR-based measurement of TL. The relation between stressful life events and TL was analysed using structural equation modelling, which also provided an estimate of the proportion of the total effect mediated by somatic and mental health (cardiovascular disease, body mass and depressive mood), lifestyle factors, and low grade inflammation (C-reactive protein (CRP), interleukin (IL)-6 and IL-10). Total number of stressful events experienced during the life course was not associated with TL. In terms of sensitive periods, we found that number of stressful events in childhood was associated with shorter TL (β_{per number stressful events in childhood}=-0.02(SE=-0.02); P=0.05). This relation was particularly strong for being placed away from home (β=-0.16; P<0.000). Thirty percent of the total effect of stressful events in childhood on TL was mediated by the included variables, with the largest proportion being mediated through depressive mood (16%) and CRP (9%). This study suggests that stressful events in childhood are associated with shorter TL in middle-aged men and that part of this relation is explained by depressive mood and low grade inflammation.

Lifespan adversity and later adulthood telomere length in the nationally representative US Health and Retirement Study

Stress over the lifespan is thought to promote accelerated aging and early disease. Telomere length is a marker of cell aging that appears to be one mediator of this relationship. Telomere length is associated with early adversity and with chronic stressors in adulthood in many studies. Although cumulative lifespan adversity should have bigger impacts than single events, it is also possible that adversity in childhood has larger effects on later life health than adult stressors, as suggested by models of biological embedding in early life. No studies have examined the individual vs. cumulative effects of childhood and adulthood adversities on adult telomere length. Here, we examined the relationship between cumulative childhood and adulthood adversity, adding up a range of severe financial, traumatic, and social exposures, as well as comparing them to each other, in relation to salivary telomere length. We examined 4,598 men and women from the US Health and Retirement Study. Single adversities tended to have nonsignificant relations with telomere length. In adjusted models, lifetime cumulative adversity predicted 6% greater odds of shorter telomere length. This result was mainly due to childhood adversity. In adjusted models for cumulative childhood adversity, the occurrence of each additional childhood event predicted 11% increased odds of having short telomeres. This result appeared mainly because of social/traumatic exposures rather than financial exposures. This study suggests that the shadow of childhood adversity may reach far into later adulthood in part through cellular aging.

Perceived stress and telomere length: A systematic review, meta-analysis, and methodologic considerations for advancing the field

IMPORTANCE

Psychological stress contributes to numerous diseases and may do so in part through damage to telomeres, protective non-coding segments on the ends of chromosomes.

OBJECTIVE

We conducted a systematic review and meta-analysis to determine the association between self-reported, perceived psychological stress (PS) and telomere length (TL).

DATA SOURCES

We searched 3 databases (PubMed, PsycInfo, and Scopus), completed manual searches of published and unpublished studies, and contacted all study authors to obtain potentially relevant data.

STUDY SELECTION

Two independent reviewers assessed studies for original research measuring (but not necessarily reporting the correlation between) PS and TL in human subjects. 23 studies met inclusion criteria; 22 (totaling 8948 subjects) could be meta-analyzed.

DATA EXTRACTION AND SYNTHESIS

We assessed study quality using modified MINORS criteria. Since not all included studies reported PS-TL correlations, we obtained them via direct calculation from author-provided data (7 studies), contact with authors (14 studies), or extraction from the published article (1 study).

MAIN OUTCOMES AND MEASURES

We conducted random-effects meta-analysis on our primary outcome, the age-adjusted PS-TL correlation. We investigated potential confounders and moderators (sex, life stress exposure, and PS measure validation) via post hoc subset analyses and meta-regression.

RESULTS

Increased PS was associated with a very small decrease in TL (n=8724 total; r=-0.06; 95% CI: -0.10, -0.008; p=0.01; α=0.025), adjusting for age. This relationship was similar between sexes and within studies using validated measures of PS, and marginally (nonsignificantly) stronger among samples recruited for stress exposure (r=-0.13; vs. general samples: b=-0.11; 95% CI: -0.27, 0.01; p=0.05; α=0.013). Publication bias may exist; correcting for its effects attenuated the relationship.

CONCLUSIONS AND RELEVANCE

Our analysis finds a very small, statistically significant relationship between increased PS (as measured over the past month) and decreased TL that may reflect publication bias, although fully parsing the effects of publication bias from other sample-size correlates is challenging, as discussed. The association may be stronger with known major stressors and is similar in magnitude to that noted between obesity and TL. All included studies used single measures of short-term stress; the literature suggests long-term chronic stress may have a larger cumulative effect. Future research should assess for potential confounders and use longitudinal, multidimensional models of stress.

Systematic review of the association between chronic social stress and telomere length: A life course perspective

Our aim was to examine whether chronic social stress is associated with telomere length throughout the life course, following our protocol published in 2014. Structured searches were conducted in MEDLINE (PubMed interface), EMBASE (OVID interface), Cochrane Central (OVID interface) and grey from their start date onwards. Reference lists of retrieved citations were hand searched for relevant studies. Eighteen studies published until May 1, 2015 investigating the association between chronic social stress (as defined by poverty, exposure to violence, or family caregiving) and telomere length in healthy or diseased adults and children were independently selected by 2 reviewers. Sixteen of those studies were cross-sectional and two had a longitudinal design. Studies differed in type of stress exposure, method to measure telomere length and cell type. As meta-analysis could not be conducted, the data were synthesized as a narrative review. Based on this comprehensive review, chronic social stress accompanies telomere shortening in both early and adult exposures, with most eligible studies showing a significant relationship. We discuss the significance of chronic stress of social origin and the potential for social interventions through public policies and we recommend methodological improvements that would allow for future meta-analysis.

Early and recent psychosocial stress and telomere length in older adults

BACKGROUND

Psychosocial stress has been associated with an increased risk for mental and somatic health problems across the life span. Some studies in younger adults linked this to accelerated cellular aging, indexed by shortened telomere length (TL). In older adults, the impact of psychosocial stress on TL may be different due to the lifetime exposure to competing causes of TL-shortening. This study aims to assess whether early and recent psychosocial stressors (childhood abuse, childhood adverse events, recent negative life events, and loneliness) were associated with TL in older adults.

METHODS

Data were from the Netherlands Study of Depression in Older Persons (NESDO) in which psychosocial stressors were measured in 496 persons aged 60 and older (mean age 70.6 (SD 7.4) years) during a face-to-face interview. Leukocyte TL was determined using fasting blood samples by performing quantitative polymerase chain reaction (qPCR) and was expressed in base pairs (bp).

RESULTS

Multiple regression analyses, adjusted for age, sex, and chronic diseases, showed that childhood abuse, recent negative life events and loneliness were unrelated to TL. Only having experienced any childhood adverse event was weakly but significantly negatively associated with TL.

CONCLUSIONS

Our findings did not consistently confirm our hypothesis that psychosocial stress is associated with shorter TL in older adults. Healthy survivorship or other TL-damaging factors such as somatic health problems seem to dominate a potential effect of psychosocial stress on TL in older adults.

Depression and telomere length: A meta-analysis

BACKGROUND

Several recent studies have investigated the relationship between telomere length and depression with inconsistent results. This meta-analysis examined whether telomere length and depression are associated and explored factors that might affect this association.

METHODS

Studies measuring telomere length in subjects with clinically significant unipolar depression were included. A comprehensive search strategy identified studies in PubMed, MEDLINE, PsycINFO, Global Health, The Cochrane Library, and Web of Science. A structured data abstraction form was used and studies were appraised for inclusion or exclusion using a priori conditions. Analyses were conducted using standardized mean differences in a continuous random effects model.

RESULTS

Thirty-eight studies (N=34,347) met the inclusion criteria. The association between depression and telomere length was significant, with a Cohen's d effect size of -0.205 (p<0.0001, I(2)=42%). Depression severity significantly associated with telomere length (p=0.03). Trim and fill analysis indicated the presence of publication bias (p=0.003), but that the association remained highly significant after accounting for the bias. Subgroup analysis revealed depression assessment tools, telomere measurement techniques, source tissue and comorbid medical conditions significantly affected the relationship.

LIMITATIONS

Other potentially important sub-groups, including antidepressant use, have not been investigated in sufficient detail or number yet and thus were not addressed in this meta-analysis.

CONCLUSIONS

There is a negative association between depression and telomere length. Further studies are needed to clarify potential causality underlying this association and to elucidate the biology linking depression and this cellular marker of stress exposure and aging.

Religious Involvement and Telomere Length in Women Family Caregivers

Telomere length (TL) is an indicator of cellular aging associated with longevity and psychosocial stress. We examine here the relationship between religious involvement and TL in 251 stressed female family caregivers recruited into a 2-site study. Religious involvement, perceived stress, caregiver burden, depressive symptoms, and social support were measured and correlated with TL in whole blood leukocytes. Results indicated a U-shaped relationship between religiosity and TL. Those scoring in the lowest 10% on religiosity tended to have the longest telomeres (5743 bp ± 367 vs. 5595 ± 383, p = 0.069). However, among the 90% of caregivers who were at least somewhat religious, religiosity was significantly and positively related to TL after controlling for covariates (B = 1.74, SE = 0.82, p = 0.034). Whereas nonreligious caregivers have relatively long telomeres, we found a positive relationship between religiosity and TL among those who are at least somewhat religious.

Are Anxiety Disorders Associated with Accelerated Aging? A Focus on Neuroprogression

Anxiety disorders (AnxDs) are highly prevalent throughout the lifespan, with detrimental effects on daily-life functioning, somatic health, and quality of life. An emerging perspective suggested that AnxDs may be associated with accelerated aging. In this paper, we explored the association between AnxDs and hallmarks of accelerated aging, with a specific focus on neuroprogression. We reviewed animal and human findings that suggest an overlap between processes of impaired neurogenesis, neurodegeneration, structural, functional, molecular, and cellular modifications in AnxDs, and aging. Although this research is at an early stage, our review suggests a link between anxiety and accelerated aging across multiple processes involved in neuroprogression. Brain structural and functional changes that accompany normal aging were more pronounced in subjects with AnxDs than in coevals without AnxDs, including reduced grey matter density, white matter alterations, impaired functional connectivity of large-scale brain networks, and poorer cognitive performance. Similarly, molecular correlates of brain aging, including telomere shortening, Aβ accumulation, and immune-inflammatory and oxidative/nitrosative stress, were overrepresented in anxious subjects. No conclusions about causality or directionality between anxiety and accelerated aging can be drawn. Potential mechanisms of this association, limitations of the current research, and implications for treatments and future studies are discussed.

A prospective study of leukocyte telomere length and risk of phobic anxiety among women

We prospectively examined the relation of relative telomere lengths (RTLs), a marker of biological aging, to phobic anxiety in later-life. RTLs in peripheral blood leukocytes were measured among 3194 women in the Nurses' Health Study who provided blood samples in 1989/90. The Crown-Crisp Phobic Index (CCI, range=0–16) was assessed in 1988 and 2004. Only participants with CCI≤3 (consistent with no meaningful anxiety symptoms) in 1988 were included. We related baseline RTLs to odds ratios (ORs) of incident high phobic anxiety symptoms (CCI≥6). To enhance clinical relevance, we used finite mixture modeling (FMM) to relate baseline RTLs to latent classes of CCI in 2004. RTLs were not significantly associated with high phobic anxiety symptoms after 16 years of follow-up. However, FMM identified 3 groups of phobic symptoms in later-life: severe, minimal/intermediate, and non-anxious. The severe group had non-significantly shorter multivariable-adjusted mean RTLs than the minimal/intermediate and non-anxious groups. Women with shorter telomeres vs. longest telomeres had non-significantly higher likelihood of being in the severe vs. non-anxious group. Overall, there was no significant association between RTLs and incident phobic anxiety symptoms. Further work is required to explore potential connections of telomere length and emergence of severe phobic anxiety symptoms during later-life.

The Association of Early and Recent Psychosocial Life Stress With Leukocyte Telomere Length

OBJECTIVES

Chronic exposure to psychosocial stressors is related to worse somatic health. This association applies both to stressors early in life, such as childhood adversities, and more recent life stress, such as stressful life events. This study examined whether accelerated telomere shortening, as an indicator of cellular aging, might be an explanatory mechanism.

METHODS

We examined whether childhood adversities and recent stressful life events were associated with shorter telomeres in 2936 participants (mean [standard deviation] age = 41.8 [13.1] years, 66% women, 57% current depression) of the Netherlands Study of Depression and Anxiety. Telomeres are specialized nucleic acid-protein complexes at the ends of linear DNA that shorten with age; telomere length (TL) was measured with quantitative polymerase chain reaction.

RESULTS

Childhood life events (β = .004, p = .805) and childhood trauma (β = -.023, p = .205) were not related to shorter TL. However, we found negative associations between recent stressful life events and TL. Persons had shorter telomeres if they reported more stressful life events in the past year (β = -.039, p = .028) and 1 to 5 years ago (β = -.042, p = .018, adjusted for sociodemographics). The relationship between stressful life events and TL became borderline significant when further adjusted for smoking status. No associations with TL were found when stressful life events occurred more than 6 years ago (p > .10).

CONCLUSIONS

Results show that recent stressful life events are associated with shorter TL. This association is not observed for psychosocial stressors that occur earlier in life. Whether these results are indicative of physiological resiliency remains to be explored by future longitudinal research.

Is childhood stress associated with shorter telomeres?

BACKGROUND

It has been shown that severe stress in childhood is harmful to later health. New research aims to ascertain whether – and if so, how – the telomeres, the protective caps at the end of our chromosomes, may be one of the links between this type of experience and later morbidity. Here we present an overview of studies which have examined the association between stress in childhood and length of telomeres.

METHOD

The review encompasses 26 original studies found through a literature search in PubMed. We included studies of the relationship between length of telomeres and various stress-inducing factors from conception throughout childhood and adolescence.

RESULTS

The studies were grouped into four topics. The empirical research base for mother's stress in pregnancy and parents' ability to care for their children is too small to draw any conclusions. Psychosocial stress in childhood was associated with shorter telomere length in 12 of 14 studies. Socioeconomic status in childhood was not unequivocally associated with telomere length.

INTERPRETATION

Shorter telomeres are possibly associated with psychosocial stress in childhood. This field of research is still new, and more longitudinal studies are needed with an emphasis on childhood experiences and coordination of measurement variables and results measurement in order to confirm this association.

Telomere length and telomerase in a well-characterized sample of individuals with major depressive disorder compared to controls

BACKGROUND

Leukocyte telomere length (LTL) is a marker of cellular turnover and oxidative stress. Studies suggest major depressive disorder (MDD) is associated with oxidative stress, but examinations of MDD and LTL have yielded mixed results, likely because of differences in measurement methods and unmeasured confounding. This study examined LTL and telomerase activity in 166 individuals with MDD compared to 166 age- and gender-matched matched controls free of any psychiatric disorder, using well-validated assays and clinical assessment methods, and controlling for a range of potential confounders.

METHODS

Subjects aged 18 to 70 were evaluated by trained raters and provided blood for LTL and telomerase activity measurement. LTL was assayed using Southern blot and replicated with qPCR, and telomerase activity was assayed with a repeat amplification protocol using a commercial kit.

RESULTS

There was no significant difference in telomere length for individuals with MDD [mean (SD)=9.1 (3.0)kbp] compared to controls [mean(SD)=8.9(2.5)kbp] measured by Southern blot (p=0.65) or by confirmatory qPCR (p=0.91) assays. Controlling for potential confounders did not alter the results. Telomerase activity did not differ by MDD diagnosis overall (p=0.40), but the effect of MDD was significantly modified by gender (t(299)=2.67, p=0.0079) even after controlling for potential confounders, with telomerase activity significantly greater only in males with MDD versus controls.

CONCLUSION

Our well-characterized, well-powered examination of concurrently assessed telomere length and telomerase activity in individuals with clinically significant, chronic MDD and matched controls failed to provide strong evidence of an association of MDD with shorter LTL, while telomerase activity was higher in men with MDD [corrected].

Psychiatric disorders and leukocyte telomere length: Underlying mechanisms linking mental illness with cellular aging

Many psychiatric illnesses are associated with early mortality and with an increased risk of developing physical diseases that are more typically seen in the elderly. Moreover, certain psychiatric illnesses may be associated with accelerated cellular aging, evidenced by shortened leukocyte telomere length (LTL), which could underlie this association. Shortened LTL reflects a cell's mitotic history and cumulative exposure to inflammation and oxidation as well as the availability of telomerase, a telomere-lengthening enzyme. Critically short telomeres can cause cells to undergo senescence, apoptosis or genomic instability, and shorter LTL correlates with poorer health and predicts mortality. Emerging data suggest that LTL may be reduced in certain psychiatric illnesses, perhaps in proportion to exposure to the psychiatric illnesses, although conflicting data exist. Telomerase has been less well characterized in psychiatric illnesses, but a role in depression and in antidepressant and neurotrophic effects has been suggested by preclinical and clinical studies. In this article, studies on LTL and telomerase activity in psychiatric illnesses are critically reviewed, potential mediators are discussed, and future directions are suggested. A deeper understanding of cellular aging in psychiatric illnesses could lead to re-conceptualizing them as systemic illnesses with manifestations inside and outside the brain and could identify new treatment targets.

Perceived Stress Levels, Chemotherapy, Radiation Treatment and Tumor Characteristics Are Associated with a Persistent Increased Frequency of Somatic Chromosomal Instability in Women Diagnosed with Breast Cancer: A One Year Longitudinal Study

While advances in therapeutic approaches have resulted in improved survival rates for women diagnosed with breast cancer, subsets of these survivors develop persistent psychoneurological symptoms (fatigue, depression/anxiety, cognitive dysfunction) that compromise their quality of life. The biological basis for these persistent symptoms is unclear, but could reflect the acquisition of soma-wide chromosomal instability following the multiple biological/psychological exposures associated with the diagnosis/treatment of breast cancer. An essential first step toward testing this hypothesis is to determine if these cancer-related exposures are indeed associated with somatic chromosomal instability frequencies. Towards this end, we longitudinally studied 71 women (ages 23-71) with early-stage breast cancer and quantified their somatic chromosomal instability levels using a cytokinesis-blocked micronuclear/cytome assay at 4 timepoints: before chemotherapy (baseline); four weeks after chemotherapy initiation; six months after chemotherapy (at which time some women received radiotherapy); and one year following chemotherapy initiation. Overall, a significant change in instability frequencies was observed over time, with this change differing based on whether the women received radiotherapy (p=0.0052). Also, significantly higher instability values were observed one year after treatment initiation compared to baseline for the women who received: sequential taxotere/doxorubicin/cyclophosphamide (p<0.001) or taxotere/cyclophosphamide (p=0.014). Significant predictive associations for acquired micronuclear/cytome abnormality frequencies were also observed for race (p=0.0052), tumor type [luminal B tumors] (p=0.0053), and perceived stress levels (p=0.0129). The impact of perceived stress on micronuclear/cytome frequencies was detected across all visits, with the highest levels of stress being reported at baseline (p =0.0024). These findings suggest that the cancer-related exposome has an impact on both healthy somatic cells and tumor cells, and may lead to persistent chromosomal instability. In addition, stress was a significant predictor of chromosomal instability; thus, interventions that aim to reduce stress may reduce acquired soma-wide chromosomal instability for cancer survivors.

Telomere length and common disease: study design and analytical challenges

Telomeres, the repetitive sequences that protect the ends of chromosomes, help to maintain genomic integrity and are of key importance to human health. The aim here is to give an overview of the evidence for the importance of telomere length (TL) to the risk of common disease, considering the strengths and weaknesses of different epidemiological study designs. Methods for measuring TL are described, all of which are subject to considerable measurement error. TL declines with age and varies in relation to factors such as smoking and obesity. It is also highly heritable (estimated heritability of ~40 to 50%), and genome-wide studies have identified a number of associated genetic variants. Epidemiological studies have shown shorter TL to be associated with risk of a number of common diseases, including cardiovascular disease and some cancers. The relationship with cancer appears complex, in that longer telomeres are associated with higher risk of some cancers. Prospective studies of the relationship between TL and disease, where TL is measured before diagnosis, have numerous advantages over retrospective studies, since they avoid the problems of reverse causality and differences in sample handling, but they are still subject to potential confounding. Studies of the genetic predictors of TL in relation to disease risk avoid these drawbacks, although they are not without limitations. Telomere biology is of major importance to the risk of common disease, but the complexities of the relationship are only now beginning to be understood.

Childhood Physical and Sexual Abuse History and Leukocyte Telomere Length among Women in Middle Adulthood

OBJECTIVE

Abuse victimization in childhood is associated with a variety of age-related cardiometabolic diseases, but the mechanisms remain unknown. Telomeres, which form the protective caps at the ends of chromosomes, have been proposed as measures of biological age, and a growing body of research suggests that telomere attrition may help to explain relationships between stress and cardiometabolic degradation. We examined the association between childhood abuse victimization and leukocyte telomere length among 1,135 participants in the Nurses' Health Study II (NHSII).

METHODS

The NHSII ascertained physical and sexual child abuse histories in 2001. Telomere length was measured in genomic DNA extracted from peripheral blood leukocytes collected between 1996 and 1999. The ratio of telomere repeat copy number to a single gene copy number (T/S) was determined by a modified version of the quantitative real-time PCR telomere assay. Telomere length was log-transformed and corrected for assay variation across batch. We regressed telomere length on childhood abuse exposure variables and covariates using linear regression.

RESULTS

We observed a reduction in telomere length associated with moderate physical abuse versus no physical abuse, but there was no evidence of a dose-response relationship for increased severity of physical abuse. No associations were noted for sexual abuse.

CONCLUSIONS

We found no evidence of an association between severity of childhood physical or sexual abuse and leukocyte telomere length in the NHSII.

The quantified self: closing the gap between general knowledge and particular case?

RATIONALE, AIMS AND OBJECTIVES

This paper addresses the movements 'evidence-based' (EBM) and 'personalized' (PM) medicine. The former is being criticized for failing to do justice to clinical complexity and human individuality. The latter aims at tailoring medical knowledge for every patient in a personalized fashion. Instrumental to this effort is the technological development engendering unlimited amounts of data about bodily fragments. The aim of this article is to stimulate a debate about the notion of the body and knowledge in medicine.

METHODS

An authentic sickness history is used as a vantage point for a more comprehensive account of biomedicine.

RESULTS

The analysis of the sickness history demonstrates how biomedical logic guided all approaches in the care for this particular patient. Each problem was identified and treated separately, whereby neglecting the interaction between body parts and systems, and between the woman's bodily condition and her experiences. The specialists involved seemed to look for phenomena that fit categories of disorders 'belonging' to their field. These approaches engendered unintended effects: chronification, poly-pharmacy and multi-morbidity, leading to an unsustainable increase in medical costs.

CONCLUSIONS

The article elucidates how the status that professionals ascribe to the body has vital implications for what they regard as relevant and how they interpret the information they have collected. On this ground, we challenge both the prevailing and tacitly accepted separation between the physical body and human experience and the view of knowledge underpinning EBM and PM. The growing molecularization of the body veils decisive sources of human illness.

Integrative Medicine Patients Have High Stress, Pain, and Psychological Symptoms

CONTEXT

Integrative medicine (IM) is a rapidly growing field whose providers report clinical success in treating significant stress, chronic pain, and depressive and anxiety symptoms. While IM therapies have demonstrated efficacy for numerous medical conditions, IM for psychological symptoms has been slower to gain recognition in the medical community.

OBJECTIVE AND DESIGN

This large, cross-sectional study is the first of its kind to document the psychosocial profiles of 4182 patients at 9 IM clinics that form the BraveNet Practice-Based Research Network (PBRN).

RESULTS

IM patients reported higher levels of perceived stress, pain, and depressive symptoms, and lower levels of quality of life compared with national norms. Per provider reports, 60% of patients had at least one of the following: stress (9.3%), fatigue (10.2%), anxiety (7.7%), depression (7.2%), and/or sleep disorders (4.8%). Pain, having both physiological and psychological components, was also included and is the most common condition treated at IM clinics. Those with high stress, psychological conditions, and pain were most frequently treated with acupuncture, IM physician consultation, exercise, chiropractic services, diet/nutrition counseling, and massage.

CONCLUSION

With baseline information on clinical presentation and service utilization, future PBRN studies can examine promising interventions delivered at the clinic to treat stress and psychological conditions.

The association between depression and leukocyte telomere length: a meta-analysis

BACKGROUND

Telomeres protect the ends of chromosomes, and shorter leukocyte telomeres are associated with poor health. Depression may be associated with the shortening of leukocyte telomeres. The present study set out to consolidate the varying effect sizes found so far in studies of depression and telomere length and to identify moderators of the relationship between depression and telomere length.

METHODS

A meta-analytic investigation of the relationship between depression and leukocyte telomere length used information from 21,040 participants.

RESULTS

A significant effect size, r = -.12, P < .001, indicated that depression was associated with shorter telomere length. Several variables significantly moderated effect size. Concurrent associations (k = 25) between depression and telomere length were significantly stronger than longitudinal associations (k = 5). Studies that used the Southern blot (k = 3) and fluorescent in situ hybridization (FISH; k = 2) assays to measure telomere length showed larger effect sizes than studies that used quantitative polymerase chain reaction (qPCR; k = 25). Finally, study reports that indicated that the telomere assays were conducted blind to depression level of participants (k = 11) had significantly lower effect sizes than those of other studies (k = 19).

CONCLUSIONS

The significant relationship between depression and shorter telomere length is consistent with a theoretical model positing that distress, such as experienced in depression, results in physiological changes leading to shortened telomeres.

Telomeres, early-life stress and mental illness

Telomeres are structures of tandem TTAGGG repeats that are found at the ends of chromosomes and preserve genomic DNA by serving as a disposable buffer to protect DNA termini during chromosome replication. In this process, the telomere itself shortens with each cell division and can consequently be thought of as a cellular 'clock', reflecting the age of a cell and the time until senescence. Telomere shortening and changes in the levels of telomerase, the enzyme that maintains telomeres, occur in the context of certain somatic diseases and in response to selected physical stressors. Emerging evidence indicates that telomeres shorten with exposure to psychosocial stress (including early-life stress) and perhaps in association with some psychiatric disorders. These discoveries suggest that telomere shortening might be a useful biomarker for the overall stress response of an organism to various pathogenic conditions. In this regard, telomeres and their response to both somatic and psychiatric illness could serve as a unifying stress-response biomarker that crosses the brain/body distinction that is often made in medicine. Prospective studies will help to clarify whether this biomarker has broad utility in psychiatry and medicine for the evaluation of responses to psychosocial stressors. The possibility that telomere shortening can be slowed or reversed by psychiatric and psychosocial interventions could represent an opportunity for developing novel preventative and therapeutic approaches.