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

Mediating role of accelerated aging in the association between depression and mortality risk: findings from NHANES

OBJECTIVE

To investigate the association between depression, accelerated biological aging, and mortality risk, and to assess whether accelerated aging mediates the relationship between major depression and mortality risk.

METHODS

A prospective cohort of 12,761 participants aged 20 years or older from the 2005-2010 cycle of the National Health and Nutrition Examination Survey (NHANES) was analyzed. Depression was assessed using the Patient Health Questionnaire-9 (PHQ-9), with scores of ≥ 10 indicating major depression. Accelerated biological aging was measured using phenotypic age acceleration (PhenoAgeAccel). Multivariable linear regression models and subgroup analyses were used to examine the association between depression and accelerated aging, while weighted multivariable Cox proportional hazards regression models and subgroup analyses assessed the impact of major depression on mortality risk. Mediation analysis was performed to assess whether PhenoAgeAccel mediated the relationship between major depression and mortality outcomes.

RESULTS

Among the 12,761 adults, the weighted mean age was 46.6 years, with 48.8% being male, and 6.9% experiencing major depression. The results showed a positive association between major depression and PhenoAgeAccel (β: 0.61, 95% CI: 0.06-1.16). Over a median follow-up duration of 11.3 years (interquartile range: 9.9-13.1), major depression was associated with increased all-cause mortality (HR: 1.35, 95% CI: 1.13-1.62) and cardiovascular mortality (HR: 1.73, 95% CI: 1.18-2.54). However, the relationship with cancer mortality was not statistically significant after full adjustment for confounding factors. The mediation analysis further revealed that PhenoAgeAccel accounted for 10.32% and 5.12% of the associations between major depression and all-cause mortality, and cardiovascular mortality, respectively.

CONCLUSION

Depression is associated with accelerated aging and contributes to increased all-cause and cardiovascular mortality. Accelerated aging partially mediates the association between major depression and mortality risk. Our findings highlight the urgent need to incorporate mental health care into public health strategies to delay population aging and reduce mortality risk.

Childhood Maltreatment and Biological Aging in Middle Adulthood: The Role of Psychiatric Symptoms

Background

Childhood maltreatment and psychiatric morbidity have each been associated with accelerated biological aging primarily through cross-sectional studies. Using data from a prospective longitudinal study of individuals with histories of childhood maltreatment and control participants followed into midlife, we tested 2 hypotheses examining whether 1) psychiatric symptoms mediate the relationship between childhood maltreatment and biological aging and 2) psychiatric symptoms of anxiety, depression, or posttraumatic stress disorder (PTSD) act in conjunction with childhood maltreatment to exacerbate the association of child maltreatment to aging.

Methods

Children (ages 0-11 years) with documented histories of maltreatment and demographically matched control children were followed into adulthood (N = 607) and interviewed over several waves of the study. Depression, anxiety, and PTSD symptoms were assessed at mean ages of 29 (interview 1) and 40 (interview 2) years. Biological age was measured from blood chemistries collected later (mean age = 41 years) using the Klemera-Doubal method. Hypotheses were tested using linear regressions and path analyses.

Results

Adults with documented histories of childhood maltreatment showed more symptoms of depression, PTSD, and anxiety at both interviews and more advanced biological aging, compared with control participants. PTSD symptoms at both interviews and depression and anxiety symptoms only at interview 2 predicted accelerated biological aging. There was no evidence of mediation; however, anxiety and depression moderated the relationship between childhood maltreatment and biological aging.

Conclusions

These new findings reveal the shorter- and longer-term longitudinal impact of PTSD on biological aging and the amplifying effect of anxiety and depression on the relationship between child maltreatment and biological aging.

Geroscience-Centric Perspective for Geriatric Psychiatry: Integrating Aging Biology With Geriatric Mental Health Research

The geroscience hypothesis asserts that physiological aging is caused by a small number of biological pathways. Despite the explosion of geroscience research over the past couple of decades, the research on how serious mental illnesses (SMI) affects the biological aging processes is still in its infancy. In this review, we aim to provide a critical appraisal of the emerging literature focusing on how we measure biological aging systematically, and in the brain and how SMIs affect biological aging measures in older adults. We will also review recent developments in the field of cellular senescence and potential targets for interventions for SMIs in older adults, based on the geroscience hypothesis.

Exploration of the causal effects of leukocyte telomere length and four gastrointestinal diseases: a two-sample bidirectional Mendelian randomization study

BACKGROUND

To explore the underlying causality between leukocyte telomere length (LTL) and four gastrointestinal diseases, we designed a two-sample bidirectional Mendelian randomization study.

METHODS

Two-sample Mendelian randomization (MR) was used to explore genetic causality between LTL and four gastrointestinal diseases, including irritable bowel syndrome (IBS), gastroesophageal reflux disease (GERD), gastrointestinal ulcers disease (GUD), and nonalcoholic fatty liver disease (NAFLD). We utilized inverse-variance weighted (IVW) as the primary method for MR analysis. Supplementary analyses were conducted using methods such as MR-Egger regression, weighted-median, Maximum Likelihood (MaxLik), Robust adjusted profile score (MR-RAPS), Contamination mixture (ConMix), and MR-mix. Cochran's Q was calculated to check for heterogeneity. The MR-Egger regression and MR pleiotropy residual sum and outlier (MR-PRESSO) were detected for pleiotropy.

RESULTS

The IVW analysis suggests that there may be a potential causal relationship between LTL and two diseases (odds ratio (OR): 1.062; 95% confidence interval (CI): 1.003, 1.124; p = 0.038 for IBS and OR: 0.889; 95% CI: 0.798, 0.990; p = 0.032 for GERD). However, other methods do not entirely align with the results of the IVW analysis. In the reverse MR analysis, we did not find statistically significant associations between LTL and these four diseases.

CONCLUSION

The current evidence does not definitively rule out a causal relationship between LTL and these four gastrointestinal diseases but suggests a potential association between LTL and IBS, or LTL and GERD. Exploring the relationship between gastrointestinal diseases and LTL may offer new insights into the onset, progression, and treatment of these diseases.

Depressive symptoms and shorter survival in lung cancer: the role of leukocyte telomere length

OBJECTIVE

To examine the association between depressive symptoms, leukocyte telomere length-a marker of cellular ageing, and survival amongst lung cancer patients.

DESIGN

Patients with non-small cell lung cancer were recruited from a university-affiliated cancer center clinic.

MAIN OUTCOME

Patients (N = 67) reported on depressive symptoms and provided a blood sample for leukocyte telomere length assessment at baseline and at a 3-month follow-up. Survival status was tracked over 3 years.

RESULTS

Age at diagnosis and depressive symptoms, as measured by the CES-D, were associated with shorter leukocyte telomere length (p < .05), although only age at diagnosis contributed statistical significance to the model. Depressive symptoms predicted shorter survival from date of diagnosis (p < .01). Patients who reported experiencing clinically meaningful levels of depressive symptoms (CES-D scores ≥ 16) demonstrated shorter survival than those who reported sub-clinical levels of depressive symptoms (p < .05). Leukocyte telomere length did not emerge as a predictor of shorter survival.

CONCLUSION

Clinically meaningful levels of depressive symptoms are associated with shorter survival amongst lung cancer patients. These findings support the on-going efforts to screen all cancer patients for low mood and to investigate mechanisms linking depressive symptoms and shorter survival in cancer contexts.

Telomere Length Associations With Clinical Diagnosis, Age, and Polygenic Risk Scores for Anxiety Disorder, Depression, and Bipolar Disorder

Background

Accelerated biological aging might contribute to the lower life expectancy of individuals with mental disorders. The aim of this study was to characterize telomere length, a biological hallmark of aging, in individuals with mental disorders.

Methods

The UK Biobank is a multicenter community-based observational study that recruited >500,000 middle-aged and older adults. Average leukocyte telomere length (telomere repeat copy number/single-copy gene ratio) was measured using quantitative polymerase chain reaction. Polygenic risk scores (PRSs) were calculated for individuals of European ancestry. We estimated differences in telomere length between individuals with anxiety disorder, depression, or bipolar disorder and people without mental disorders and examined associations with psychotropic medication use, age, and PRSs for these 3 disorders.

Results

The analyses included up to 308,725 participants. Individuals with depression had shorter telomeres than people without mental disorders (β = -0.011, 95% CI, -0.019 to -0.004, Bonferroni-corrected p = .027). Associations between bipolar disorder and telomere length differed by lithium use. There was limited evidence that individuals with an anxiety disorder had shorter telomeres. There was no evidence that associations between age and telomere length differed between individuals with and without these disorders. PRSs for depression, but not anxiety disorder or bipolar disorder, were associated with shorter telomeres (β = -0.006, 95% CI, -0.010 to -0.003, Bonferroni-corrected p = .001).

Conclusions

Differences in telomere length were observed primarily for individuals with depression or bipolar disorder and in individuals with a higher PRS for depression. There was no evidence that the association between age and telomere length differed between individuals with and without an anxiety disorder, depression, or bipolar disorder.

Associations of depression and anxiety and adolescent telomere length

BACKGROUND

Telomere length (TL), a biomarker of cellular aging, is influenced by adverse life experiences. Although depression and anxiety are associated with shorter TL in adults, the relationship in younger ages has received little attention. We examined relationships between depression and anxiety diagnoses and symptomatology and TL in adolescence, an important developmental window for early intervention. Sex differences in relationships were also examined.

METHODS

Wave 1 survey and TL data from the Adolescent Health and Development in Context study were analyzed (N = 995). Depression and anxiety diagnosis were parent-reported measures categorized as: current diagnosis, prior diagnosis, and never diagnosed (reference category). Depressive symptoms were measured via adolescent-report using nine items from the Center for Epidemiologic Studies-Depression scale, short form. Anxiety symptoms were measured via adolescent-report using eight items from the pediatric anxiety scale obtained from the Patient-Reported Outcomes Measurement Information System. Genomic DNA was isolated from 500 μL saliva via ethanol precipitation. Genomic DNA TL was assessed using monoplexed quantitative polymerase chain reactions. Relative T/S quantities were calculated in accordance with established procedures. Covariates included sociodemographic factors (sex, age, race/ethnicity, caregiver marital status and education level, and household income), pubertal development, and season of collection. Descriptive and multivariable linear regression analyses were conducted, including an examination of sex as a moderator in the relationships between depression, anxiety, and TL.

RESULTS

In multivariable analysis, adolescents with a current depression diagnosis (b = -0.26, p < .05), but not a prior diagnosis (b =0.05, p > .05) had shorter TL than those who were never diagnosed; higher depressive symptom scores were associated with shorter TL (b = -0.12, p < .05). No significant associations were found between anxiety diagnosis and TL; however, higher anxiety symptom scores were associated with shorter TL (b = -0.14, p < .01). Sex did not significantly moderate any of the relationships between depression, anxiety and TL.

CONCLUSIONS

Depression and anxiety were associated with shorter TL in this diverse community sample of adolescents and the findings highlight the potential for impaired mental health to contribute to cellular senescence as early as adolescence. Prospective research on the long-term effect of depression and anxiety occurring earlier in the life span on TL over time is needed, including examination of potential mechanisms that may accelerate or buffer the negative effects of impaired mental health on TL.

Telomere length and chronological age across the human lifespan: A systematic review and meta-analysis of 414 study samples including 743,019 individuals

Telomere attrition is a proposed hallmark of aging. To evaluate the association of telomere length (TL) with chronological age across the human lifespan, we conducted a systematic review and meta-analysis of 414 study samples comprising 743,019 individuals aged 0-112 years. We examined both cross-sectional and longitudinal data, and evaluated the impact of various biological and methodological factors including sex, health status, tissue types, DNA extraction procedures, and TL measurement methods. The pooled corrected correlation between TL and age from cross-sectional samples was -0.19 (95%CI: -0.22 to -0.15), which weakened with increased chronological age (β = 0.003, p < 0.001). Z-score change rates of TL across the lifespan showed a gradual decrease in shortening rate until around age 50 and remained at a relatively stable rate towards the elderly period. A greater attrition rate was observed in longitudinal than cross-sectional evaluations. For TL measured in base pairs, the median change rate of TL was -23 bp/year in cross-sectional samples and -38 bp/year in longitudinal samples. Methodological factors including TL measurement methods and tissue types impacted the TL-age correlation, while sex or disease status did not. This meta-analysis revealed the non-linear shortening trend of TL across the human lifespan and provides a reference value for future studies. Results also highlight the importance of methodological considerations when using TL as an aging biomarker.

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.

Psychosocial Factors and Telomere Length Among Parents and Infants of Immigrant Arab American Families

Background: Immigrant Arab American families face multiple stressors related to migration and resettlement. Telomere length (TL) is an established biomarker of aging and psychosocial stress. No published studies have concurrently examined the association between maternal and paternal psychosocial factors and infants' TL. The purpose of this study was to: (1) compare mother, father, and infant TLs; (2) explore the association of maternal and paternal psychosocial factors (acculturative stress and depressive symptoms) with maternal and paternal TL; and (3) explore the association of maternal and paternal psychosocial factors with infants' TL among Arab American immigrants. Method: Using a cross-sectional exploratory design, a sample of 52 immigrant Arab American mother-father-infant triads were recruited from community centers. Data were collected in a single home visit when the infant was 6-24 months old. Each parent completed the study questionnaires addressing their psychosocial factors (acculturative stress, and depressive symptoms), then parents and infants provided buccal cell for TL measurement. Results: Maternal TL was positively correlated to infants' TL (r = .31, p = .04) and significantly shorter (p < .001). Paternal TL was not correlated with infant TL but was significantly shorter than infant's TL (p < .001). Maternal depression was significantly correlated with mothers' TL (r = .4, p = .007). Higher levels of maternal depressive symptoms were significantly associated with shorter infant TL when controlling for background characteristics. Conclusions: Our pilot study is the first study to examine maternal and paternal psychosocial factors related to migration and infants' TL. More research is needed to advance our understanding of the effects of immigration on the intergenerational transfer of stress and trauma.

Major depression and the biological hallmarks of aging

Major depressive disorder (MDD) is characterized by psychological and physiological manifestations contributing to the disease severity and outcome. In recent years, several lines of evidence have suggested that individuals with MDD have an elevated risk of age-related adverse outcomes across the lifespan. This review provided evidence of a significant overlap between the biological abnormalities in MDD and biological changes commonly observed during the aging process (i.e., hallmarks of biological aging). Based on such evidence, we formulate a mechanistic model showing how abnormalities in the hallmarks of biological aging can be a common denominator and mediate the elevated risk of age-related health outcomes commonly observed in MDD. Finally, we proposed a roadmap for novel studies to investigate the intersection between the biology of aging and MDD, including the use of geroscience-guided interventions, such as senolytics, to delay or improve major depression by targeting biological aging.

A healthy lifestyle is positively associated with mental health and well-being and core markers in ageing

BACKGROUND

Studies often evaluate mental health and well-being in association with individual health behaviours although evaluating multiple health behaviours that co-occur in real life may reveal important insights into the overall association. Also, the underlying pathways of how lifestyle might affect our health are still under debate. Here, we studied the mediation of different health behaviours or lifestyle factors on mental health and its effect on core markers of ageing: telomere length (TL) and mitochondrial DNA content (mtDNAc).

METHODS

In this study, 6054 adults from the 2018 Belgian Health Interview Survey (BHIS) were included. Mental health and well-being outcomes included psychological and severe psychological distress, vitality, life satisfaction, self-perceived health, depressive and generalised anxiety disorder and suicidal ideation. A lifestyle score integrating diet, physical activity, smoking status, alcohol consumption and BMI was created and validated. On a subset of 739 participants, leucocyte TL and mtDNAc were assessed using qPCR. Generalised linear mixed models were used while adjusting for a priori chosen covariates.

RESULTS

The average age (SD) of the study population was 49.9 (17.5) years, and 48.8% were men. A one-point increment in the lifestyle score was associated with lower odds (ranging from 0.56 to 0.74) for all studied mental health outcomes and with a 1.74% (95% CI: 0.11, 3.40%) longer TL and 4.07% (95% CI: 2.01, 6.17%) higher mtDNAc. Psychological distress and suicidal ideation were associated with a lower mtDNAc of - 4.62% (95% CI: - 8.85, - 0.20%) and - 7.83% (95% CI: - 14.77, - 0.34%), respectively. No associations were found between mental health and TL.

CONCLUSIONS

In this large-scale study, we showed the positive association between a healthy lifestyle and both biological ageing and different dimensions of mental health and well-being. We also indicated that living a healthy lifestyle contributes to more favourable biological ageing.

Telomere is shortened in patients with irritable bowel syndrome in the Chinese population

BACKGROUND AND AIM

Telomere shortening is an accepted indicator of aging. Many studies have investigated an association between leukocyte telomere length (LTL) and psychiatric disorders. Mental or psychological factors could be an important cause of irritable bowel syndrome (IBS). However, there are currently few research evaluating correlations between LTL and IBS.

METHODS

We examined associations between LTL and IBS using quantitative polymerase chain reaction in independent cohorts, including 205 patients with IBS and 189 healthy controls. Furthermore, we examined whether mental or psychological factors, types of IBS, duration of IBS and antidepressants had an association with LTL in patients with IBS.

RESULTS

Among total samples, patients with IBS presented shorter LTL when compared to healthy controls (P < 0.0001). Moreover, in subgroup analyses of patients with IBS, not only the LTL in patients with IBS caused by mental or psychological factors was shorter (P < 0.0001), but also in patients with IBS that were caused by other factors (P = 0.0082). Furthermore, LTL in patients with IBS who had taken antidepressants for more than 1 month was longer than that in patients with IBS who did not take antidepressants or took for less than 1 month (P < 0.0001).

CONCLUSIONS

This is the first study to describe the relationship between LTL and IBS. This study showed significantly shorter telomeres in patients with IBS. Our findings suggest that LTL may hold the potential to serve as a predictor of IBS diagnosis.

Accelerated mononuclear cell telomere attrition in breast cancer survivors with depression history: A 2-year longitudinal cohort study

BACKGROUND

Cancer treatments are thought to accelerate biological aging, although this trajectory is highly variable. Depression is more prevalent in breast cancer survivors and is thought to be a vulnerability factor for biological aging. A lifetime history of depression and cumulative lifetime number of depression episodes could hypothetically be associated with an accelerated rate of biological aging as indexed by attrition of telomere length in a prospective cohort of breast cancer survivors who were not currently depressed.

METHODS

Breast cancer survivors (n = 206) without current depression were recruited from a large community-based health plan and were assessed for depression history by a structured diagnostic interview. Blood specimens were provided at baseline and every 8 months over 24 months to measure peripheral blood mononuclear cell (PBMC) telomere length. Mixed linear models examined associations of depression history and number of depression episodes with change in telomere length, adjusting for demographic, comorbidity, and cancer-specific factors.

RESULTS

In the fully adjusted model, depression history predicted attrition of PBMC telomere length over 24 months (Beta [SE] = -.006 [.002], p = .001). Greater number of depressive episodes over the lifetime was also associated with accelerated attrition of PBMC telomere length over 24 months (Beta [SE] = -.004 [.001], p = .001).

CONCLUSIONS

In breast cancer survivors without current depression, telomere attrition over 24 months was greatest in those with a lifetime depression history, particularly those with the greatest number of episodes of major depressive disorder over their lifetime. Depression history and its cumulative burden may contribute to accelerated biological aging, with implications for risk of morbidity and mortality in breast cancer survivors.

Depression, religiosity, and telomere length in the Study on Stress, Spirituality, and Health (SSSH)

Prospective studies on the association between depression and telomere length have produced mixed results and have been largely limited to European ancestry populations. We examined the associations between depression and telomere length, and the modifying influence of religion and spirituality, in four cohorts, each representing a different race/ethnic population. Relative leukocyte telomere length (RTL) was measured by a quantitative polymerase chain reaction. Our result showed that depression was not associated with RTL (percent difference: 3.0 95% CI: -3.9, 10.5; p = 0.41; p-heterogeneity across studies = 0.67) overall or in cohort-specific analyses. However, in cohort-specific analyses, there was some evidence of effect modification by the extent of religiosity or spirituality, religious congregation membership, and group prayer. Further research is needed to investigate prospective associations between depression and telomere length, and the resources of resilience including dimensions of religion and spirituality that may impact such dynamics in diverse racial/ethnic populations.

Telomere length and telomerase activity of leukocytes as biomarkers of selective serotonin reuptake inhibitor responses in patients with major depressive disorder

We analyze the leukocyte telomere length (LTL) and telomerase activity in patients with major depressive disorder (MDD) before and after treatment with selective serotonin reuptake inhibitors (SSRIs). Before treatment, there was a reduction in the LTLs and expression levels of the human telomerase reverse transcriptase (hTERT) in the patients with MDD compared with controls. However, after 24 weeks of treatment with SSRIs, there was a significant increase in the LTLs and the expression levels of hTERT, with values approaching those observed in the controls. We conclude that SSRI antidepressant therapy can directly influence the increased expression levels of hTERT in patients.

Telomeres are shorter and associated with number of suicide attempts in affective disorders

BACKGROUND

Shorter telomere length is a putative biomarker of accelerated aging and has been associated with affective disorders and mortality. Psychological factors and behaviors associated with telomere shortening are yet to be clarified. Here, we investigate the association between history of suicide attempts and telomere length in patients with affective disorders.

METHODS

Leucocyte telomere length was determined by quantitative real-time Polymerase Chain Reaction (qPCR) in patients with affective disorders (n = 248) including bipolar disorders type I (n = 159), type II (n = 67), major depressive disorder (n = 22), and healthy controls (n = 401). Diagnosis, duration of illness, and age at onset were assessed using the Structural Clinical Interview for DSM-IV (SCID-I). Number of lifetime suicide attempts were based on self-reports. Effect size was calculated using Cohen's d.

RESULTS

Telomere length was reduced in patients with affective disorders relative to healthy controls (d = 0.18, F = 5.26, p = 0.02). Among patients, a higher number of suicide attempts was associated with shorter telomere length (β = -0.24, t = -3.83, CI = -0.44 to -0.14, p < 0.001), also when controlling for duration of illness and age at onset (β = -.23, CI = -.42 to -.12, p = 0.001). Multiple suicide attempts were associated with telomere length reduction comparable to eight years lifespan, adjusted for demographic and clinical characteristics.

CONCLUSIONS

While longitudinal data are needed to clarify the temporal course, previous suicide attempts and related distress may accelerate telomere shortening and aging in patients with affective disorders.

Cross-species Association Between Telomere Length and Glucocorticoid Exposure

CONTEXT

Chronic exposure to glucocorticoids (GCs) or stress increases the risk of medical disorders, including cardiovascular and neuropsychiatric disorders. GCs contribute to accelerated aging; however, while the link between chronic GC exposure and disease onset is well established, the underpinning mechanisms are not clear.

OBJECTIVE

We explored the potential nexus between GCs or stress exposure and telomere length.

METHODS

In addition to rats exposed to 3 weeks of chronic stress, an iatrogenic mouse model of Cushing syndrome (CS), and a mouse neuronal cell line, we studied 32 patients with CS and age-matched controls and another cohort of 75 healthy humans.

RESULTS

(1) Exposure to stress in rats was associated with a 54.5% (P = 0.036) reduction in telomere length in T cells. Genomic DNA (gDNA) extracted from the dentate gyrus of stressed and unstressed rats showed 43.2% reduction in telomere length (P = 0.006). (2) Mice exposed to corticosterone had a 61.4% reduction in telomere length in blood gDNA (P = 5.75 × 10-5) and 58.8% reduction in telomere length in the dentate gyrus (P = 0.002). (3) We observed a 40.8% reduction in the telomere length in patients with active CS compared to healthy controls (P = 0.006). There was a 17.8% reduction in telomere length in cured CS patients, which was not different from that of healthy controls (P = 0.08). For both cured and active CS, telomere length correlated significantly with duration of hypercortisolism (R2 = 0.22, P = 0.007). (4) There was a 27.6% reduction in telomere length between low and high tertiles in bedtime cortisol levels of healthy participants (P = 0.019).

CONCLUSION

Our findings demonstrate that exposure to stress and/or GCs is associated with shortened telomeres, which may be partially reversible.

Investigating the Role of Leukocyte Telomere Length in Treatment-Resistant Depression and in Response to Electroconvulsive Therapy

Psychiatric disorders seem to be characterized by premature cell senescence. However, controversial results have also been reported. In addition, the relationship between accelerated aging and treatment-resistance has scarcely been investigated. In the current study, we measured leukocyte telomere length (LTL) in 148 patients with treatment-resistant depression (TRD, 125 with major depressive disorder, MDD, and 23 with bipolar disorder, BD) treated with electroconvulsive therapy (ECT) and analyzed whether LTL was associated with different response profiles. We also compared LTL between patients with TRD and 335 non-psychiatric controls. For 107 patients for which genome-wide association data were available, we evaluated whether a significant overlap among genetic variants or genes associated with LTL and with response to ECT could be observed. LTL was negatively correlated with age (Spearman’s correlation coefficient = −0.25, p < 0.0001) and significantly shorter in patients with treatment-resistant MDD (Quade’s F = 35.18, p < 0.0001) or BD (Quade’s F = 20.84, p < 0.0001) compared to controls. Conversely, baseline LTL was not associated with response to ECT or remission. We did not detect any significant overlap between genetic variants or genes associated with LTL and response to ECT. Our results support previous findings suggesting premature cell senescence in patients with severe psychiatric disorders and suggest that LTL could not be a predictive biomarker of response to ECT.

Linking the Triad of Telomere Length, Inflammation, and Gut Dysbiosis in the Manifestation of Depression

Telomere length is an indispensable marker for cellular and biological aging, and it also represents an individual's physical and mental health status. Telomere shortening has been observed in chronic inflammatory conditions, which in turn accelerates aging and risk for psychiatric disorders, including depression. Considering the influence of inflammation and telomere shortening on the gut-brain axis, herein we describe a plausible interplay between telomere attrition, inflammation, and gut dysbiosis in the neurobiology of depression. Telomere shortening and hyperinflammation are well reported in depression. A negative impact of augmented inflammation has been noted on the intestinal permeability and microbial consortia and their byproducts in depressive patients. Moreover, gut dysbiosis provokes host-immune responses. As the gut microbiome is gaining importance in the manifestation and management of depression, herein we discuss whether telomere attrition is connected with the perturbation of commensal microflora. We also describe a pathological connection of cortisol with hyperinflammation, telomere shortening, and gut dysbiosis occurring in depression. This review summarizes how the triad of telomere attrition, inflammation, and gut dysbiosis is interconnected and modulates the risk for depression by regulating the systemic cortisol levels.

Telomere shortening in late-life depression: A potential marker of depression severity

OBJECTIVES

Telomeres are structures at the extremity of chromosomes that prevents genomic instability, and its shortening seems to be a hallmark of cellular aging. Past studies have shown contradictory results of telomere length (TL) in major depression, and are a few studies in late-life depression (LLD). This explores the association between TL as a molecular marker of aging and diagnosis of LLD, the severity of depressive symptoms, and cognitive performance in older adults.

METHODS/DESIGN

We included 78 older adults (45 with LLD and 33 nondepressed controls, according to DSM-V criteria), aged 60-90 years. TL was measured in leukocytes by a quantitative polymerase chain reaction, determining the relative ratio (T/S) between the telomere region copy number (T) and a single copy gene (S), using a relative standard curve.

RESULTS

TL was significantly shorter in the LLD compared with control participants (p = .039). Comparing groups through the severity of depressive symptoms, we found a negative correlation with the severity of depressive symptoms (Hamilton Depression Rating Scale-21, r = -0.325, p = .004) and medical burden (r = -0.271, p = .038). There was no significant correlation between TL and cognitive performance (Mattis Dementia Rating Scale, r = 0.152, p = .21).

CONCLUSIONS

We found that older adults with LLD have shorter telomere than healthy controls, especially those with a more severe depressive episode. Our findings suggest that shorter TL can be a marker of the severity of depressive episodes in older adults and indicate that these individuals may be at higher risk of age-associated adverse outcomes linked to depression.

The association of telomere length with substance use disorders: a systematic review and meta-analysis of observational studies

BACKGROUND AND AIMS

Several recent studies have investigated the relationship between telomere length and substance use disorders with inconsistent results. We aimed to assess this association and to identify moderators of the relationship.

METHODS

Systematic review and meta-analysis. Selection criteria were observational studies reporting telomere length in people with a substance use disorder compared with a control group. Studies focused solely on nicotine addiction, employing other study designs, and non-human studies were excluded. Study selection and data extraction were independently conducted by two researchers following a standardized protocol and included studies until December 2019. Standardized mean differences were used as the effect size index [d; 95% confidence interval (CI)] and random-effects models were used for the meta-analysis. Cochran's Q-statistic, I² index, visual inspection of the forest plot and a 95% prediction interval were applied to verify study heterogeneity. Subgroup analyses and meta-regressions were conducted to explore heterogeneity. Small study effects were examined using the 'funnel plot', the Egger test, Duval & Tweedie's trim-and-fill method and the precision-effect test-precision-effect estimate with standard error (PET-PEESE) method. The risk of bias and the quality of evidence were assessed.

RESULTS

Ten studies (12 analysis units with 2671 cases and 4532 controls) met the selection criteria. An overall effect size of moderate magnitude was found (d₊  = -0.63; 95% CI = -1.00 and -0.26; P = 0.0008). A potential small study effect was detected, as well as large heterogeneity between studies (Q-statistic P < 0.001, I²  = 97.3%). Selection of controls, reporting laboratory quality control procedures and total sample size significantly affected the effect size. The quality of the evidence was very low, based on risk of bias analysis and the grading of recommendations assessment, development and evaluation (GRADE) system.

CONCLUSIONS

People with substance use disorders appear to have shorter telomere length than controls; however, this finding should be interpreted with caution due to the poor quality of the evidence.

Telomere Shortening and Psychiatric Disorders: A Systematic Review

Telomeres are aging biomarkers, as they shorten while cells undergo mitosis. The aim of this study was to evaluate whether psychiatric disorders marked by psychological distress lead to alterations to telomere length (TL), corroborating the hypothesis that mental disorders might have a deeper impact on our physiology and aging than it was previously thought. A systematic search of the literature using MeSH descriptors of psychological distress ("Traumatic Stress Disorder" or "Anxiety Disorder" or "depression") and telomere length ("cellular senescence", "oxidative stress" and "telomere") was conducted on PubMed, Cochrane Library and ScienceDirect databases. A total of 56 studies (113,699 patients) measured the TL from individuals diagnosed with anxiety, depression and posttraumatic disorders and compared them with those from healthy subjects. Overall, TL negatively associates with distress-related mental disorders. The possible underlying molecular mechanisms that underly psychiatric diseases to telomere shortening include oxidative stress, inflammation and mitochondrial dysfunction linking. It is still unclear whether psychological distress is either a cause or a consequence of telomere shortening.

A systematic review of the association between biological markers and environmental stress risk factors for adolescent depression

INTRODUCTION

Although the aetiology and pathophysiology of depression are multifactorial, to date most studies have examined either biological or environmental mechanisms without looking at the integration of both; with most studies conducted in high-income countries (HICs). Therefore, we conducted a systematic review of worldwide studies investigating the relationship between biological and environmental stress risk factors for major depressive disorder (MDD) in adolescence.

METHODS

We searched MEDLINE (via Ovid), PsycINFO, Cochrane Database of Systematic Reviews, Web of Science (Core Collection), Lilacs, African Journals Online and Global Health for prospective and cross-sectional studies that examined the association between biological markers and environmental stress risk factors in MDD during adolescence.

FINDINGS

Of 11,089 articles identified, 21 were included, with only two from middle-income countries. Increased inflammation, telomere length and brain abnormalities, including blunted reward-related activity, white matter disruptions, and altered volume of limbic brain regions, were associated with increased risk for MDD mainly in the context of early life adversity. There is little evidence suggesting that the neurobiological changes investigated were associated with MDD in the context of recent life stress.

INTERPRETATION

The developmental trajectory of depression appears to start with early life adversities and occurs in the context of immune and brain abnormalities. Understanding these biopsychosocial processes will help to improve our ability to detect individuals at risk of developing depression in adolescence. However, generalizability is limited by few studies examining both biological and environmental stress risk factors and a lack of studies on adolescents and young adults in low-and-middle-income countries (LMICs).

Discrimination and Leukocyte Telomere Length by Depressive Symptomatology: The Jackson Heart Study

Background: Psychosocial stressors, such as perceived discrimination and depressive symptoms, may shorten telomeres and exacerbate aging-related illnesses. Methods: Participants from the Jackson Heart Study at visit 1 (2000–2004) with LTL data and Center for Epidemiological Studies-Depression (CES-D) scores (n = 580 men, n = 910 women) were utilized. The dimensions of discrimination scores (everyday, lifetime, burden of lifetime, and stress from lifetime discrimination) were standardized and categorized as low, moderate, and high. Coping responses to everyday and lifetime discrimination were categorized as passive and active coping. Multivariable linear regression analyses were performed to estimate the mean difference (standard errors-SEs) in LTL by dimensions of discrimination and coping responses stratified by CES-D scores < 16 (low) and ≥ 16 (high) and sex. Covariates were age, education, waist circumference, smoking and CVD status. Results: Neither everyday nor lifetime discrimination was associated with mean differences in LTL for men or women by levels of depressive symptoms. Burden of lifetime discrimination was marginally associated with LTL among women who reported low depressive symptoms after full adjustment (b = 0.11, SE = 0.06, p = 0.08). Passive coping with lifetime discrimination was associated with longer LTL among men who reported low depressive symptoms after full adjustment (b = 0.18, SE = 0.09, p < 0.05); and active coping with lifetime discrimination was associated with longer LTL among men who reported high depressive symptoms after full adjustment (b = 1.18, SE = 0.35, p < 0.05). Conclusions: The intersection of perceived discrimination and depressive symptomatology may be related to LTL, and the effects may vary by sex.

Accelerated brain aging predicts impulsivity and symptom severity in depression

Multiple structural and functional neuroimaging measures vary over the course of the lifespan and can be used to predict chronological age. Accelerated brain aging, as quantified by deviations in the MRI-based predicted age with respect to chronological age, is associated with risk for neurodegenerative conditions, bipolar disorder, and mortality. Whether age-related changes in resting-state functional connectivity are accelerated in major depressive disorder (MDD) is unknown, and, if so, it is unclear if these changes contribute to specific cognitive weaknesses that often occur in MDD. Here, we delineated age-related functional connectivity changes in a large sample of normal control subjects and tested whether brain aging is accelerated in MDD. Furthermore, we tested whether accelerated brain aging predicts individual differences in cognitive function. We trained a support vector regression model predicting age using resting-state functional connectivity in 710 healthy adults aged 18-89. We applied this model trained on normal aging subjects to a sample of actively depressed MDD participants (n = 109). The difference between predicted brain age and chronological age was 2.11 years greater (p = 0.015) in MDD patients compared to control participants. An older MDD brain age was significantly associated with increased impulsivity and, in males, increased depressive severity. Unexpectedly, accelerated brain aging was also associated with increased placebo response in a sham-controlled trial of high-frequency repetitive transcranial magnetic stimulation targeting the dorsomedial prefrontal cortex. Our results indicate that MDD is associated with accelerated brain aging, and that accelerated aging is selectively associated with greater impulsivity and depression severity.

TERT rs2736100 and TERC rs16847897 genotypes moderate the association between internalizing mental disorders and accelerated telomere length attrition among HIV+ children and adolescents in Uganda

BACKGROUND

Internalizing mental disorders (IMDs) (depression, anxiety and post-traumatic stress disorder) have been associated with accelerated telomere length (TL) attrition; however, this association has not been investigated in the context of genetic variation that has been found to influence TL. We have previously reported an association between IMDs and accelerated TL attrition among Ugandan HIV+ children and adolescents. This study investigated the moderating effects of selected single nucleotide polymorphisms in the telomerase reverse transcriptase gene (TERT) (rs2736100, rs7726159, rs10069690 and rs2853669) and the telomerase RNA component gene (TERC) (rs12696304, rs16847897 and rs10936599) on the association between IMDs and TL, among Ugandan HIV+ children (aged 5-11 years) and adolescents (aged 12-17 years).

RESULTS

We found no significant interaction between IMDs as a group and any of the selected SNPs on TL at baseline. We observed significant interactions of IMDs with TERT rs2736100 (p = 0.007) and TERC rs16847897 (p = 0.012), respectively, on TL at 12 months.

CONCLUSIONS

TERT rs2736100 and TERC rs16847897 moderate the association between IMDs and TL among Ugandan HIV+ children and adolescents at 12 months. Understanding the nature of this association may shed light on the pathophysiological mechanisms underlying advanced cellular aging in IMDs.

PBMC telomerase activity in depression and the response to electroconvulsive therapy

Telomerase, the DNA polymerase responsible for maintaining telomere length, has previously been implicated in depression and the response to antidepressant drugs. In this study, we aimed to compare telomerase activity in peripheral blood mononuclear cells between patients with severe depression recruited as part of the KEEP-WELL Trial (Ketamine for Depression Relapse Prevention Following ECT; NCT02414932) and age- and sex-matched healthy volunteers both at baseline/pre-ECT and at follow-up 1 month later for controls or in patients after a course of ECT. We found no differences in telomerase activity between patients with depression (n = 20) compared to healthy controls (n = 33) at baseline/pre-ECT, or between patients treated with ECT compared to controls at follow-up. In patients, telomerase activity was not associated with mood, as assessed by the 24-item Hamilton Rating Scale for Depression, or the duration of the current depressive episode. Additionally, we found no significant relationship between telomerase activity and exposure to recent or childhood adversity in either the patient or control groups. Overall, our results suggest that telomerase activity is not associated with depression, the therapeutic response to ECT, or exposure to adversity.

Depressive Symptoms Predict Change in Telomere Length and Mitochondrial DNA Copy Number Across Adolescence

OBJECTIVE

Several studies have found associations between a diagnosis or symptoms of major depressive disorder and markers of cellular aging and dysfunction. These investigations, however, are predominantly cross-sectional and focus on adults. In the present study, we used a prospective longitudinal design to test the cross-sectional association between depressive symptoms in adolescents and telomere length (TL) as well as mitochondrial DNA copy number (mtDNA-cn).

METHOD

A total of 121 adolescents (mean age = 11.38 years, SD = 1.03; 39% male adolescents and 61% female adolescents) were followed for approximately 2 years. At baseline and follow-up, participants provided saliva for DNA extraction, from which measures of TL and mtDNA-cn were obtained. Depressive symptoms were obtained via the Children's Depression Inventory.

RESULTS

There was no association between depressive symptoms and markers of cellular aging at baseline; however, depressive symptoms at baseline predicted higher rates of telomere erosion (β = -0.201, p = .016) and greater increases in mtDNA-cn (β = 0.190, p = .012) over the follow-up period. Markers of cellular aging at baseline did not predict subsequent changes in depressive symptoms. Furthermore, including the number of stressful life events did not alter these patterns of findings.

CONCLUSION

These results indicate that depressive symptoms precede changes in cellular aging and dysfunction, rather than the reverse.

Telomere attrition and inflammatory load in severe psychiatric disorders and in response to psychotropic medications

Individuals with severe psychiatric disorders have a reduced life expectancy compared to the general population. At the biological level, patients with these disorders present features that suggest the involvement of accelerated aging, such as increased circulating inflammatory markers and shorter telomere length (TL). To date, the role of the interplay between inflammation and telomere dynamics in the pathophysiology of severe psychiatric disorders has been scarcely investigated. In this study we measured T-lymphocytes TL with quantitative fluorescent in situ hybridization (Q-FISH) and plasma levels of inflammatory markers in a cohort comprised of 40 patients with bipolar disorder (BD), 41 with schizophrenia (SZ), 37 with major depressive disorder (MDD), and 36 non-psychiatric controls (NPC). TL was shorter in SZ and in MDD compared to NPC, while it was longer in BD (model F6, 137 = 20.128, p = 8.73 × 10-17, effect of diagnosis, F3 = 31.870; p = 1.08 × 10-15). There was no effect of the different classes of psychotropic medications, while duration of treatment with mood stabilizers was associated with longer TL (Partial correlation controlled for age and BMI: correlation coefficient = 0.451; p = 0.001). Levels of high-sensitivity C-Reactive Protein (hsCRP) were higher in SZ compared to NPC (adjusted p = 0.027), and inversely correlated with TL in the whole sample (r = -0.180; p = 0.042). Compared to NPC, patients with treatment resistant (TR) SZ had shorter TL (p = 0.001), while patients with TR MDD had higher levels of tumor necrosis factor-α (TNFα) compared to NPC (p = 0.028) and to non-TR (p = 0.039). Comorbidity with cardio-metabolic disorders did not influence the observed differences in TL, hsCRP, and TNFα among the diagnostic groups. Our study suggests that patients with severe psychiatric disorders present reduced TL and increased inflammation.

Epigenetic clock as a correlate of anxiety

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In young adult women, slower epigenetic clock predicted less symptoms of anxiety.

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In young adult women, slower epigenetic clock predicted greater cortical GM volume.

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This effect of epigenetic clock in young adult women was largest in frontal lobe.

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The link of epigenetic clock and anxiety was mediated by GM volume in frontal lobe.

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No similar relationships were found in young adult men or adolescents.

DNA methylation changes consistently throughout life and age-dependent alterations in DNA methylation can be used to estimate one’s epigenetic age. Post-mortem studies revealed higher epigenetic age in brains of patients with major depressive disorder, as compared with controls. Since MDD is highly correlated with anxiety, we hypothesized that symptoms of anxiety, as well as lower volume of grey matter (GM) in depression-related cortical regions, will be associated with faster epigenetic clock in a community-based sample of young adults. Participants included 88 young adults (53% men; 23–24 years of age) from the European Longitudinal Study of Pregnancy and Childhood (ELSPAC) who participated in its neuroimaging follow-up and provided saliva samples for epigenetic analysis. Epigenetic age was calculated according to Horvath (Horvath, 2013). Women had slower epigenetic clock than men (Cohen’s d = 0.48). In women (but not men), slower epigenetic clock was associated with less symptoms of anxiety. In the brain, women (but not men) with slower epigenetic clock had greater GM volume in the cerebral cortex (brain size-corrected; R² = 0.07). Lobe-specific analyses showed that in women (but not men), slower epigenetic clock was associated with greater GM volume in frontal lobe (R² = 0.16), and that GM volume in frontal lobe mediated the relationship between the speed of epigenetic clock and anxiety trait (ab = 0.15, SE = 0.15, 95% CI [0.007; 0.369]). These findings were not replicated, however, in a community-based sample of adolescents (n = 129; 49% men; 12–19 years of age), possibly due to the different method of tissue collection (blood vs. saliva) or additional sources of variability in the cohort of adolescents (puberty stages, socioeconomic status, prenatal exposure to maternal smoking during pregnancy).

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.

Inverse changes in telomere length between the blood and brain in depressive-like mice

BACKGROUND

Telomeres are nucleoprotein complexes located at the end of chromosomes. Previous studies have confirmed that telomere length is reduced in the peripheral blood of depression patients. However, studies regarding whether telomere length is altered in brain regions associated with depression are limited. It remains unclear whether the peripheral blood telomere length indicates telomere variation in the brain.

METHODS

Using quantitative PCR, we measured telomere length in five brain regions (prefrontal cortex, amygdala, nucleus accumbens, paraventricular nucleus, and hippocampus) from depressive-like mice and in peripheral blood from depressive-like mice and major depressive disorder (MDD) patients. We also examined the expression of telomerase- and alternative lengthening of telomere (ALT)-related genes in the prefrontal cortex and amygdala of depressive-like mice.

RESULTS

Telomeres were shortened in the peripheral blood of depressive-like mice and MDD patients, but were elongated in the prefrontal cortex and amygdala compared with healthy controls. We also observed that the expression of ALT-related genes increased in the prefrontal cortex and amygdala.

LIMITATIONS

The amount of human sample was limited. The mechanism of telomere lengthening in the brain of depressive-like mice was not well explained. Mice and humans have inherently different telomere and telomere maintenance systems.

CONCLUSION

These findings illustrate that the telomere length in the peripheral blood may not indicate the dynamics of telomere length in the brain. They offer a new perspective on variable telomere length in different brain regions affected in depression and provide a new basis for understanding the relationship between variable telomere length and MDD.

Longitudinal changes in telomere length in a cohort of obese patients submitted to bariatric surgery: a 2-year follow-up

BACKGROUND

Telomere length (TL) is one biomarker of cell aging used to explore the effects of the environment on age-related pathologies. Obesity and high body mass index have been identified as a risk factors for shortened TL.

OBJECTIVE

To evaluate TL in different subtypes of obese patients, and to examine changes in TL in relation to weight loss after bariatric surgery.

SETTING

University Hospital in Spain.

METHODS

A cohort of 94 patients submitted to bariatric surgery were followed-up during 24 months (t_24m: lost to follow-up = 0%). All patients were evaluated before surgery (t₀) and during the postoperative period (t_6m, t_12m, and t_24m) for body mass index and metabolic variables. We assessed TL at each timepoint using quantitative polymerase chain reactions and the telomere sequence to single-copy gene sequence ratio method.

RESULTS

Patients with class III obesity showed significantly shorter TL at baseline than those patients with class II obesity (P = .027). No differences in TL were found between patients with or without type 2 diabetes or metabolic syndrome. Longitudinal analysis did not show an effect of time, type of surgery, age, or sex on TL. However, a generalized estimating equation model showed that TL was shorter amongst class III obesity patients across the time course (P = .008). Comparison between patients with obesity class II and class III showed differences in TL at t_6m (adjusted P = .024), whereby class II patients had longer TL. However, no difference was observed at the other evaluated times.

CONCLUSION

Obesity severity may have negative effects on TL independently of type 2 diabetes or metabolic syndrome. Although TL is significantly longer in class II obesity patients relative to class III 6 months after bariatric surgery. This difference is not apparent after 24 months.

Religiosity, depression and telomere length in Chinese older adults

BACKGROUND

The mechanism explaining how religiosity is linked to telomere length (TL) is unclear. The current study examines depression as a possible mediator.

METHODS

In this cross-sectional study of 1,742 community-dwelling residents aged 55 or over, the Duke University Religion Index (DUREL) and Geriatric Depression Scale (GDS) were administrated during a routine health check. Peripheral blood leukocyte TL was determined using a q-PCR procedure. The Bootstrap methods PROCESS program was used to detect mediation.

RESULTS

After controlling for sociodemographic variables, the religiosity was positively correlated with TL (p<0.05) and negatively correlated with depressive symptom (p<0.001). Depressive symptoms, in turn, was negatively correlated with TL (p<0.05) in the overall sample. Depressive symptoms significantly mediated the relationship between religiosity and TL (explaining 31.8% of the total variance) in the 65 years and older subgroup (p = 0.015). No significant mediation was found in the 55-64 age subgroup.

LIMITATIONS

The cross-sectional design prevents making causal inferences. The non-random sampling method used in selecting participants may affect the external validity of the findings in terms of generalizing to Muslims throughout China or other religious groups. Potential mediators of the relationship between religiosity and TL and confounders such as physical health status, were not assessed.

CONCLUSION

Religiosity was positively associated with TL in older mainland Chinese adults, and this association was partially mediated by depressive symptom in the 65 or older age group. This finding helps to explain why religiosity is related to cellular aging in older adults.

The association of telomere length with substance use disorders: systematic review and meta-analysis protocol

BACKGROUND

The present protocol was designed for a systematic review and meta-analysis aimed at determining the association of telomere length with substance use disorders with the exclusion of nicotine addiction, and to identify potential moderators of the effect of telomere length. Such methodological information may provide guidance to improve the quality of future research on this important topic.

METHODS

Potential studies will be identified through electronic databases (PubMed/MEDLINE, EMBASE, PsycINFO, and Web of Science) up from inception onwards. The inclusion criteria will include published or unpublished observational studies (cohort, case-control, and cross-sectional studies) reporting telomere length in adult patients with substance use disorder compared with a control group. Non-human studies or other study designs such as reviews, case-only, family-based, and/or population studies with only healthy participants will be excluded, as well as those focused solely on nicotine addiction. The main outcome will be telomere length in adults with substance use disorder (primary) and, specifically, in those with alcohol use disorder (secondary). Two investigators will independently evaluate the preselected studies for possible inclusion and will extract data following a standardized protocol. Disagreements will be resolved by consensus. The risk of bias of all included studies will be assessed using the Newcastle-Ottawa Quality Assessment Scale for non-randomized studies. Data will be converted into standardized mean differences as effect size index, and random-effects models will be used for the meta-analysis. Cochran's Q statistic, I² index, and visual inspection of the forest plot will be used to verify study heterogeneity. Subgroup analyses and meta-regressions will be conducted to ascertain heterogeneity. Several sensitivity analyses will be conducted to address the influence of potential confounding factors. Publication bias will be examined using the "funnel plot" method with Duval and Tweedie's trim-and-fill method and Egger test.

DISCUSSION

This systematic review will assess the association of telomere length with substance use disorders aside from nicotine addiction.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42019119785.

Loving-kindness meditation slows biological aging in novices: Evidence from a 12-week randomized controlled trial

Combinations of multiple meditation practices have been shown to reduce the attrition of telomeres, the protective caps of chromosomes (Carlson et al., 2015). Here, we probed the distinct effects on telomere length (TL) of mindfulness meditation (MM) and loving-kindness meditation (LKM). Midlife adults (N = 142) were randomized to be in a waitlist control condition or to learn either MM or LKM in a 6-week workshop. Telomere length was assessed 2 weeks before the start of the workshops and 3 weeks after their termination. After controlling for appropriate demographic covariates and baseline TL, we found TL decreased significantly in the MM group and the control group, but not in the LKM group. There was also significantly less TL attrition in the LKM group than the control group. The MM group showed changes in TL that were intermediate between the LKM and control groups yet not significantly different from either. Self-reported emotions and practice intensity (duration and frequency) did not mediate these observed group differences. This study is the first to disentangle the effects of LKM and MM on TL and suggests that LKM may buffer telomere attrition.

Controlling for baseline telomere length biases estimates of the rate of telomere attrition

Longitudinal studies have sought to establish whether environmental exposures such as smoking accelerate the attrition of individuals' telomeres over time. These studies typically control for baseline telomere length (TL) by including it as a covariate in statistical models. However, baseline TL also differs between smokers and non-smokers, and telomere attrition is spuriously linked to baseline TL via measurement error and regression to the mean. Using simulated datasets, we show that controlling for baseline TL overestimates the true effect of smoking on telomere attrition. This bias increases with increasing telomere measurement error and increasing difference in baseline TL between smokers and non-smokers. Using a meta-analysis of longitudinal datasets, we show that as predicted, the estimated difference in telomere attrition between smokers and non-smokers is greater when statistical models control for baseline TL than when they do not, and the size of the discrepancy is positively correlated with measurement error. The bias we describe is not specific to smoking and also applies to other exposures. We conclude that to avoid invalid inference, models of telomere attrition should not control for baseline TL by including it as a covariate. Many claims of accelerated telomere attrition in individuals exposed to adversity need to be re-assessed.

Machine-learning based brain age estimation in major depression showing no evidence of accelerated aging

Molecular biological findings indicate that affective disorders are associated with processes akin to accelerated aging of the brain. The use of the BrainAGE (brain age estimation gap) framework allows machine-learning based detection of a gap between age estimated from high-resolution MRI scans an chronological age, and thus an indicator of systems-level accelerated aging. We analysed 3T high-resolution structural MRI scans in 38 major depression patients (without co-morbid axis I or II disorders) and 40 healthy controls using the BrainAGE method to test the hypothesis of accelerated aging in (non-psychotic) major depression. We found no significant difference (or trend) for elevated BrainAGE in this pilot sample. Unlike previous findings in schizophrenia (and partially bipolar disorder), unipolar depression per se does not seem to be associated with accelerated aging patterns across the brain. However, given the limitations of the sample, further study is needed to test for effects in subgroups with comorbidities, as well as longitudinal designs.

Accelerating research on biological aging and mental health: Current challenges and future directions

Aging is associated with complex biological changes that can be accelerated, slowed, or even temporarily reversed by biological and non-biological factors. This article focuses on the link between biological aging, psychological stressors, and mental illness. Rather than comprehensively reviewing this rapidly expanding field, we highlight challenges in this area of research and propose potential strategies to accelerate progress in this field. This effort requires the interaction of scientists across disciplines - including biology, psychiatry, psychology, and epidemiology; and across levels of analysis that emphasize different outcome measures - functional capacity, physiological, cellular, and molecular. Dialogues across disciplines and levels of analysis naturally lead to new opportunities for discovery but also to stimulating challenges. Some important challenges consist of 1) establishing the best objective and predictive biological age indicators or combinations of indicators, 2) identifying the basis for inter-individual differences in the rate of biological aging, and 3) examining to what extent interventions can delay, halt or temporarily reverse aging trajectories. Discovering how psychological states influence biological aging, and vice versa, has the potential to create novel and exciting opportunities for healthcare and possibly yield insights into the fundamental mechanisms that drive human aging.

Association among dispositional mindfulness, self-compassion, and leukocyte telomere length in Chinese adults

Background

Whereas meditation training has been purported to support slower cellular aging, little work has explored the association among different facets of dispositional mindfulness, self-compassion, and cellular aging. The present study aimed to examine the relationship between leukocyte telomere length (LTL), an index of cellular aging, dispositional mindfulness, and self-compassion in a sample of Singaporean Chinese adults.

Methods

One hundred and fifty-eight Chinese adults (mean age = 27.24 years; 63.3% female) were recruited from the community and completed self-report measures assessing dispositional mindfulness, self-compassion, and psychological symptoms, as well as provided blood samples for analyses of LTL. Multiple regression analyses were conducted to examine the role of trait mindfulness and self-compassion in predicting LTL, taking into consideration potential covariates such as chronological age and psychological symptoms.

Results

Results showed that nonreactivity, one of the five facets of dispositional mindfulness, was significantly associated with LTL, after controlling for chronological age. There was also a trend for dispositional mindfulness, self-compassion, and their selected facets (i.e., nonjudging, common humanity, and de-identification) to each be associated with longer LTL.

Conclusions

Overall, the findings provide preliminary support for the association among aspects of dispositional mindfulness, self-compassion, and aging. In particular, individuals high on nonreactivity experience slower aging at the cellular level, likely through engaging in more adaptive coping mechanisms.

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.

Expression of Bcl-2 and Bax genes in peripheral blood lymphocytes of depressed and nondepressed individuals

BACKGROUND

Involvement of the immune system is one of the issues raised in the pathophysiology of depression. BCL2 and BAX genes are related to immune system regulation. We investigated the BCL2 and BAX expression as a probable mechanism of immune system involvement in depression.

MATERIALS AND METHODS

This case-control study was conducted on 28 patients with major depression (case) and 28 nondepressed individuals (control) within the age range of 18-55 years in the Isfahan University of Medical Sciences. Clinical interviews, based on the Diagnostic and Statistical Manual of Mental Disorders, were conducted to detect depression, and Beck's Depression Inventory was used to measure the severity of depression in the individuals. In addition, a real-time polymerase chain reaction was employed to compare the level of Bax and Bcl-2 gene expression in peripheral blood lymphocytes. The multivariate covariance analysis was used to explore the correlation between BCL2 and BAX gene expression and to control the effect of duration and severity of depression.

RESULTS

The results showed that none of the variables including group membership, the duration of depression, and the severity of depression were not significantly correlated with the expression of BCL2 and BAX genes. Furthermore, there was no statistically significant relationship between the Bax and Bcl-2 genes expression in case and control groups (P > 0.05).

CONCLUSION

Depression may have no impact on Bax and Bcl-2 gene expression in patients with major depression. Studies with larger sample size are recommended.

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.

Association of psychosocial factors with leukocyte telomere length among African Americans in the Jackson Heart Study

Leukocyte telomere length (LTL) is a biomarker of cellular aging. African Americans report more stress than other groups; however, the association of psychosocial stressors with biological aging among African Americans remains unclear. The current study evaluated the association of psychosocial factors (negative affect and stressors) with LTL in a large sample of African American men and women (n = 2,516) from the Jackson Heart Study. Using multivariable linear regression, we examined the sex-specific associations of psychosocial factors (cynical distrust, anger in and out, depressive symptoms, negative affect summary scores, global stress, weekly stress, major life events, and stress summary scores) with LTL. Model 1 adjusted for demographics and education. Model 2 adjusted for model 1, smoking, alcohol intake, physical activity, diabetes, hypertension, and high-sensitivity C-reactive protein. Among women, high (vs. low) cynical distrust was associated with shorter mean LTL in model 1 (b = -0.12; p = 0.039). Additionally, high (vs. low) anger out and expressed negative affect summary scores were associated with shorter LTL among women after full adjustment (b = -0.13; p = 0.011; b = -0.12, p = 0.031, respectively). High levels of cynical distrust, anger out, and negative affect summary scores may be risk factors for shorter LTL, particularly among African-American women.

Unraveling the association between depression and telomere length using genomics

OBJECTIVE

While there is robust evidence for a cross-sectional association between depression and shorter telomere length, suggestive of advanced biological aging, the nature of this association remains unclear. Here, we tested whether both traits share a common genetic liability with novel methods using genomics.

METHODS

Data were from 2032 participants of the Netherlands Study of Depression and Anxiety (NESDA) with genome-wide genetic information and multiple waves of data on DSM-IV lifetime depression diagnosis, depression severity, neuroticism and telomere length. Polygenic risk scores (PRS) for both traits were built using summary results from the largest genome-wide association studies (GWAS) on depression (59,851 cases and 113,154 controls) and telomere length (37,684 samples). Additionally, a PRS for neuroticism was built (337,000 samples). Genetic overlap between the traits was tested using PRS for same- and cross-trait associations. Furthermore, GWAS summary statistics were used to estimate the genome-wide genetic correlation between traits.

RESULTS

In NESDA data, the PRS for depression was associated with lifetime depression (odds ratio = 1.36; p = 6.49e-7) and depression severity level (β = 0.13; p = 1.24e-8), but not with telomere length. Similar results were found for the PRS for neuroticism. Conversely, the PRS for telomere length was associated with telomere length (β = 0.07; p = 8.42e-4) and 6-year telomere length attrition rate (β = 0.04; p = 2.15e-2), but not with depression variables. In summary-level analyses, the genetic correlation between the traits was small and not significant (rg=-0.08; p = .300).

CONCLUSION

The use of genetic methods in this paper indicated that the established phenotypic association between telomere length and depression is unlikely due to shared underlying genetic vulnerability. Our findings suggest that short telomeres in depressed patients may simply represent a generic marker of disease or may originate from non-genetic environmental factors.

At the forefront of psychoneuroimmunology in pregnancy: Implications for racial disparities in birth outcomes: PART 2: Biological mechanisms

As reviewed in Part 1 of this two part review, birth prior to full term is a substantial public health issue. In the US, ˜400,000 babies per year are born preterm (< 37 weeks), while>1 million are early term (37-38^6/7 weeks) and remarkable racial disparities in shortened gestation are observed among African Americans as compared to Whites. Biomechanisms linking stressor exposures with birth outcomes are increasingly being explicated. The current paper reviews the mechanistic role of maternal biological functioning in the link between behavioral exposures and birth outcomes. These include the inter-related roles of neuroendocrine function, inflammatory regulation, biological aging, and the microbiome. An integrative approach which addresses both behavioral and biological factors within the same study, carefully considers the role of race/ethnicity, and rigorously defines birth outcomes (e.g., spontaneous versus medically-indicated and inclusive of early term birth) is needed to move research in this field toward better mechanistic understanding and clinical application.

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.