Association of Neighborhood Deprivation and Depressive Symptoms With Epigenetic Age Acceleration: Evidence From the Canadian Longitudinal Study on Aging

BACKGROUND

Neighborhood deprivation and depression have been linked to epigenetic age acceleration. The next-generation epigenetic clocks including the DNA methylation (DNAm) GrimAge, and PhenoAge have incorporated clinical biomarkers of physiological dysregulation by selecting cytosine-phosphate-guanine sites that are associated with risk factors for disease, and have shown improved accuracy in predicting morbidity and time-to-mortality compared to the first-generation clocks. The aim of this study is to examine the association between neighborhood deprivation and DNAm GrimAge and PhenoAge acceleration in adults, and assess interaction with depressive symptoms.

METHODS

The Canadian Longitudinal Study on Aging recruited 51 338 participants aged 45-85 years across provinces in Canada. This cross-sectional analysis is based on a subsample of 1 445 participants at baseline (2011-2015) for whom epigenetic data were available. Epigenetic age acceleration (years) was assessed using the DNAm GrimAge and PhenoAge, and measured as residuals from regression of the biological age on chronological age.

RESULTS

A greater neighborhood material and/or social deprivation compared to lower deprivation (b = 0.66; 95% confidence interval [CI] = 0.21, 1.12) and depressive symptoms scores (b = 0.07; 95% CI = 0.01, 0.13) were associated with higher DNAm GrimAge acceleration. The regression estimates for these associations were higher but not statistically significant when epigenetic age acceleration was estimated using DNAm PhenoAge. There was no evidence of a statistical interaction between neighborhood deprivation and depressive symptoms.

CONCLUSIONS

Depressive symptoms and neighborhood deprivation are independently associated with premature biological aging. Policies that improve neighborhood environments and address depression in older age may contribute to healthy aging among older adults living in predominantly urban areas.

Epigenetic Aging and Rheumatoid Arthritis

This is the first known comparative assessment of the associations of epigenetic age estimates with the prevalence of rheumatoid arthritis (RA). We used data available in Gene Expression Omnibus (GSE42861) from the Swedish Epidemiological Investigation of Rheumatoid Arthritis study. Information regarding RA diagnosis and 450K DNA methylation (DNAm) of 18- to 70-year-old participants was available. Utilizing Horvath's online DNAm Age Calculator, we determined the DNAm estimate of Telomere length (DNAmTL), Hannum's epigenetic age, Horvath's 2013 and 2018 epigenetic ages, PhenoAge, GrimAge, and the respective age-acceleration measures. The association of RA prevalence with epigenetic age measures was assessed using linear regression, adjusting for sex and smoking status. The p values were corrected for multiple testing using a false discovery rate. We identified statistically significant associations of RA with Horvath 2013 age acceleration (estimate: -1.34; FDR p value: 1.0 × 10-2), Horvath 2018 age acceleration (estimate: -1.32; FDR p value: 4.0 × 10-5), extrinsic age acceleration (estimate: 1.34; FDR p value: 1.0 × 10-2), PhenoAge acceleration (estimate: 2.31; FDR p value: 1.1 × 10-5), GrimAge (estimate: 2.54; FDR p value: 1.0 × 10-2), and GrimAge acceleration (estimate: 3.15; FDR p-value: 1.7 × 10-17). Of note, the raw and age-adjusted GrimAge surrogate DNAm protein components were significantly higher in RA cases than controls. Interestingly, the first-generation measures were associated only with women. No sex-specific effects were identified for PhenoAge or GrimAge accelerations. In this cross-sectional assessment, the second-generation clocks show promise as markers of biological aging, with higher epigenetic age acceleration observed in RA cases compared with healthy controls.

Longitudinal study of traumatic-stress related cellular and cognitive aging

Traumatic stress is associated with both accelerated epigenetic age and increased risk for dementia. Accelerated epigenetic age might link symptoms of traumatic stress to dementia-associated biomarkers, such as amyloid-beta (Aβ) proteins, neurofilament light (NFL), and inflammatory molecules. We tested this hypothesis using longitudinal data obtained from 214 trauma-exposed military veterans (85 % male, mean age at baseline: 53 years, 75 % White) who were assessed twice over the course of an average of 5.6 years. Cross-lagged panel mediation models evaluated measures of lifetime posttraumatic stress disorder and internalizing and externalizing comorbidity (assessed at Time 1; T1) in association with T1 epigenetic age (per the GrimAge algorithm) and T1 plasma markers of neuropathology along with bidirectional temporal paths between T1 and T2 epigenetic age and the plasma markers. Results revealed that a measure of externalizing comorbidity was associated with accelerated epigenetic age (β = 0.30, p <.01), which in turn, was associated with subsequent increases in Aβ-40 (β = 0.20, p <.001), Aβ-42 (β = 0.18, p <.001), and interleukin-6 (β = 0.18, p <.01). T1 advanced epigenetic age and the T1 neuropathology biomarkers NFL and glial fibrillary acidic protein predicted worse performance on T2 neurocognitive tasks assessing working memory, executive/attentional control, and/or verbal memory (ps = 0.03 to 0.009). Results suggest that advanced GrimAge is predictive of subsequent increases in neuropathology and inflammatory biomarkers as well as worse cognitive function, highlighting the clinical significance of this biomarker with respect to cognitive aging and brain health over time. The finding that advanced GrimAge mediated the association between psychiatric comorbidity and future neuropathology is important for understanding potential pathways to neurodegeneration and early identification of those at greatest risk.

Cumulative stress, PTSD, and emotion dysregulation during pregnancy and epigenetic age acceleration in Hispanic mothers and their newborn infants

Pregnancy can exacerbate or prompt the onset of stress-related disorders, such as post-traumatic stress disorder (PTSD). PTSD is associated with heightened stress responsivity and emotional dysregulation, as well as increased risk of chronic disorders and mortality. Further, maternal PTSD is associated with gestational epigenetic age acceleration in newborns, implicating the prenatal period as a developmental time period for the transmission of effects across generations. Here, we evaluated the associations between PTSD symptoms, maternal epigenetic age acceleration, and infant gestational epigenetic age acceleration in 89 maternal-neonatal dyads. Trauma-related experiences and PTSD symptoms in mothers were assessed during the third trimester of pregnancy. The MethylationEPIC array was used to generate DNA methylation data from maternal and neonatal saliva samples collected within 24 h of infant birth. Maternal epigenetic age acceleration was calculated using Horvath's multi-tissue clock, PhenoAge and GrimAge. Gestational epigenetic age was estimated using the Haftorn clock. Maternal cumulative past-year stress (GrimAge: p = 3.23e-04, PhenoAge: p = 9.92e-03), PTSD symptoms (GrimAge: p = 0.019), and difficulties in emotion regulation (GrimAge: p = 0.028) were associated with accelerated epigenetic age in mothers. Maternal PTSD symptoms were associated with lower gestational epigenetic age acceleration in neonates (p = 0.032). Overall, our results suggest that maternal cumulative past-year stress exposure and trauma-related symptoms may increase the risk for age-related problems in mothers and developmental problems in their newborns.

Metabolic syndrome accelerates epigenetic ageing in older adults: Findings from The Irish Longitudinal Study on Ageing (TILDA)

Metabolic syndrome (MetS) is a risk factor for the development of diabetes, cardiovascular disease, and all-cause mortality. It has an estimated prevalence of 40 % among older adults. Epigenetic clocks, which measure biological age based on DNA methylation (DNAm) patterns, are a candidate biomarker for ageing. GrimAge is one such clock which is based on levels of DNAm at 100 Cytosine-phosphate-Guanine (CpG) sites. This study hypothesised that those with MetS have 'accelerated ageing' (biological age greater than their chronological age) as indexed by GrimAge. This study examined MetS's association with GrimAge age acceleration (AA) using data from a subsample of 469 participants of the Irish Longitudinal Study on Ageing (TILDA). MetS was defined by National Cholesterol Education Program Third Adult Treatment Panel (ATP III) and International Diabetes Foundation (IDF) criteria, operationalised using the conventional binary cut-off, and as a count variable ranging from 0 to 5, based on the presence of individual components. This study also explored inflammation (as measured by C reactive protein) and metabolic dysfunction (as measured by adiponectin) as possible mediating factors between MetS and GrimAge AA. We found that MetS as defined by IDF criteria was associated with GrimAge AA of 0.63 years. When MetS was treated as a count, each unit increase in MetS score was associated with over 0.3 years GrimAge AA for both ATP III and IDF criteria. Inflammation mediated approximately one third of the association between MetS and GrimAge AA, suggesting that chronic subclinical inflammation observed in MetS has a relationship with DNAm changes consistent with a faster pace of ageing. Metabolic dysfunction mediated the association between MetS and GrimAge AA to a lesser extent (16 %). These data suggest that chronic subclinical inflammation observed in MetS has a relationship with DNAm changes consistent with a greater pace of ageing.

PTSD and Alcohol Use Disorders Predict the Pace of Cellular Aging

Advanced epigenetic age is associated with psychopathology and may help to explain the link between psychopathology and physical health morbidity and mortality. Using a longitudinal sample of 171 trauma-exposed Veterans, we modeled the rate of change in epigenetic age across two time points (averaging 5.58 years apart) using two epigenetic age algorithms (GrimAge and Horvath) and tested associations with posttraumatic stress disorder (PTSD), alcohol use disorder (AUD), and depression. Results showed that PTSD (β = .199) and AUD (β = .186) were associated with a quickened pace of epigenetic aging over time (ps < .021). Results replicate and extend prior work and offer foundational support for identifying interventions that slow the pace of biological aging among those with psychopathology.

Mother's childhood adversity is associated with accelerated epigenetic aging in pregnancy and in male newborns

Background

Adverse childhood experiences (ACEs) are correlated with accelerated epigenetic aging, but it is not clear whether altered epigenetic aging from childhood adversities persists into adulthood and can be transmitted to the next generation. Thus, we tested whether mothers' childhood adversity is associated with accelerated epigenetic aging during pregnancy and in their newborn offspring.

Methods

Data were from the Avon Longitudinal Study of Parents and Children (ALSPAC) sub-study, Accessible Resource for Integrated Epigenomic Studies (ARIES). Women provided retrospective self-reports during pregnancy of ACE exposure. DNA methylation was measured in mothers during pregnancy and cord blood at birth. Estimates of epigenetic age acceleration were calculated using Principal Components of Horvath, Hannum skin & blood, GrimAge, PhenoAge, and DunedinPACE epigenetic clocks for mothers; and the Knight and Bohlin cord blood clocks for newborns. Associations between a cumulative maternal ACE score and epigenetic age acceleration were estimated using linear regression models, adjusting for maternal age at pregnancy, smoking during pregnancy, education, and pre-pregnancy BMI. Models for offspring were stratified by sex and additionally adjusted for gestation age.

Results

Mothers' total ACE score was positively associated with accelerated maternal PhenoAge and GrimAge. In newborn offspring, mothers' total ACE score was positively associated with accelerated epigenetic aging in males using the Bohlin clock, but not in females using either epigenetic clock. We found male offsprings' epigenetic age was accelerated in those born to mothers exposed to neglect using the Knight clock; and parental substance abuse using the Bohlin clock.

Conclusion

Our results show that mothers' ACE exposure is associated with DNAm age acceleration in male offspring, supporting the notion that DNAm age could be a marker of intergenerational biological embedding of mothers' childhood adversity. This is consistent with findings on vulnerability of male fetuses to environmental insults.

Military Veterans

OBJECTIVE

Veterans are at high risk for health morbidities linked to premature mortality. Recently developed "epigenetic clock" algorithms, which compute intra-individual differences between biological and chronological aging, can help inform prediction of accelerated biological aging and mortality risk. To date, however, scarce research has examined potentially modifiable correlates of GrimAge, a novel epigenetic clock comprised of DNA methylation surrogates of plasma proteins and smoking pack-years associated with various morbidities and time-to-death. The objective of the study was to examine psychosocial correlates of this novel epigenetic clock.

DESIGN

Cross-sectional study.

SETTING

U.S. veteran population.

PARTICIPANTS

Participants were male, European American (EA), and derived from a nationally representative sample of U.S. veterans (N = 1,135, mean age = 63.3, standard deviation [SD] = 13.0).

MEASUREMENTS

We examined the prevalence of accelerated GrimAge and its association with a broad range of health, lifestyle, and psychosocial variables.

RESULTS

A total 18.3% of veterans had accelerated GrimAge (≥5 years greater GrimAge than chronological age; mean = 8.4 years acceleration, SD = 2.2). Fewer days of weekly physical exercise (relative variance explained [RVE] = 27%), history of lifetime substance use disorder (RVE = 21%), greater number of lifetime traumas (RVE = 19%), lower gratitude (RVE = 13%), reduced sleep quality (RVE = 7%), lower openness to experience (RVE = 7%), and unmarried/partnered status (RVE = 6%) were independently associated with increased odds of accelerated GrimAge. Increasing numbers of these risk factors were associated with greater odds of accelerated GrimAge, with greatest likelihood of acceleration for veterans with ≥3 risk factors (weighted 21.5%).

CONCLUSIONS

These results suggest that nearly 1-of-5 EA male U.S. veterans have accelerated GrimAge, and highlight a broad range of health, lifestyle, and psychosocial variables associated with accelerated GrimAge. Given that many of these factors are modifiable, these findings provide promising leads for risk stratification models of accelerated biological aging and precision medicine-based targets for interventions to mitigate risk for premature mortality in this population.

The association between adverse childhood experiences and epigenetic age acceleration in the Canadian longitudinal study on aging (CLSA)

Research examining the association between exposure to a wide range of adverse childhood experiences (ACEs) and accelerated biological aging in older adults is limited. The purpose of this study was to examine the association of ACEs, both as a cumulative score and individual forms of adversity, with epigenetic age acceleration assessed using the DNA methylation (DNAm) GrimAge and DNAm PhenoAge epigenetic clocks in middle and older-aged adults. This cross-sectional study analyzed baseline and first follow-up data on 1445 participants aged 45-85 years from the Canadian Longitudinal Study on Aging (CLSA) who provided blood samples for DNAm analysis. ACEs were assessed using a validated self-reported questionnaire. Epigenetic age acceleration was estimated by regressing each epigenetic clock estimate on chronological age. Cumulative ACEs score was associated with higher DNAm GrimAge acceleration (β: 0.07; 95% CI: 0.02, 0.11) after adjusting for covariates. Childhood exposure to parental separation or divorce (β: 0.06; 95% CI: 0.00, 0.11) and emotional abuse (β: 0.06; 95% CI: 0.00, 0.12) were associated with higher DNAm GrimAge acceleration after adjusting for other adversities and covariates. There was no statistical association between ACEs and DNAm PhenoAge acceleration. Early life adversity may become biologically embedded and lead to premature biological aging, in relation to DNAm GrimAge, which estimates risk of mortality. Strategies that increase awareness of ACEs and promote healthy child development are needed to prevent ACEs.

Life-course socioeconomic factors are associated with markers of epigenetic aging in a population-based study

Adverse socioeconomic circumstances negatively affect the functioning of biological systems, but the underlying mechanisms remain only partially understood. Here, we explore the associations between life-course socioeconomic factors and four markers of epigenetic aging in a population-based setting. We included 684 participants (52 % women, mean age 52.6 ± 15.5 years) from a population and family-based Swiss study. We used nine life-course socioeconomic indicators as the main exposure variables, and four blood-derived, second generation markers of epigenetic aging as the outcome variables (Levine's DNAmPhenoAge, DunedinPoAm38, GrimAge epigenetic age acceleration (EAA), and the mortality risk score (MS)). First, we investigated the associations between socioeconomic indicators and markers of epigenetic aging via mixed-effect linear regression models, adjusting for age, sex, participant's recruitment center, familial structure (random-effect covariate), seasonality of blood sampling, and technical covariates. Second, we implemented counterfactual mediation analysis to investigate life-course and intermediate mechanisms underlying the socioeconomic gradient in epigenetic aging. Effect-size estimates were assessed using regression coefficients and counterfactual mediation parameters, along with their respective 95 % confidence intervals. Individuals reporting a low father's occupation, adverse financial conditions in childhood, a low income, having financial difficulties, or experiencing unfavorable socioeconomic trajectories were epigenetically older and had a higher mortality risk score than their more advantaged counterparts. Specifically, this corresponded to an average increase of 1.1-1.5 years for Levine's epigenetic age (β and 95 %CI range, β (minimum and maximum): 1.1-1.5 95 %CI[0.0-0.2; 2.3-3.0]), 1.1-1.5 additional years for GrimAge (β: 1.1-1.5 95 %CI[0.2-0.6; 1.9-3.0]), a 1-3 % higher DunedinPoAm38 age acceleration (β: 0.01-0.03 95 %CI[0.00; 0.03-0.04]), and a 10-50 % higher MS score (β: 0.1-0.4 95 %CI[0.0-0.2; 0.3-0.4]) for the aforementioned socioeconomic indicators. By exploring the life-course mechanisms underlying the socioeconomic gradient in epigenetic aging, we found that both childhood and adulthood socioeconomic factors contributed to epigenetic aging, and that detrimental lifestyle factors mediated the relation between socioeconomic circumstances in adulthood and EAA (31-89 % mediated proportion). This study provides emerging evidence for an association between disadvantaged life-course socioeconomic circumstances and detrimental epigenetic aging patterns, supporting the "sensitive-period" life-course model. Counterfactual mediation analyses further indicated that the effect of socioeconomic factors in adulthood operates through detrimental lifestyle factors, whereas associations involving early-life socioeconomic factors were less clear.

BMI is positively associated with accelerated epigenetic aging in twin pairs discordant for body mass index

BACKGROUND

Obesity is a heritable complex phenotype that can increase the risk of age-related outcomes. Biological age can be estimated from DNA methylation (DNAm) using various "epigenetic clocks." Previous work suggests individuals with elevated weight also display accelerated aging, but results vary by epigenetic clock and population. Here, we utilize the new epigenetic clock GrimAge, which closely correlates with mortality.

OBJECTIVES

We aimed to assess the cross-sectional association of body mass index (BMI) with age acceleration in twins to limit confounding by genetics and shared environment.

METHODS AND RESULTS

Participants were from the Finnish Twin Cohort (FTC; n = 1424), including monozygotic (MZ) and dizygotic (DZ) twin pairs, and DNAm was measured using the Illumina 450K array. Multivariate linear mixed effects models including MZ and DZ twins showed an accelerated epigenetic age of 1.02 months (p-value = 6.1 × 10^-12 ) per one-unit BMI increase. Additionally, heavier twins in a BMI-discordant MZ twin pair (ΔBMI >3 kg/m² ) had an epigenetic age 5.2 months older than their lighter cotwin (p-value = 0.0074). We also found a positive association between log (homeostatic model assessment of insulin resistance) and age acceleration, confirmed by a meta-analysis of the FTC and two other Finnish cohorts (overall effect = 0.45 years, p-value = 4.1 × 10^-25 ) from adjusted models.

CONCLUSION

We identified significant associations of BMI and insulin resistance with age acceleration based on GrimAge, which were not due to genetic effects on BMI and aging. Overall, these results support a role of BMI in aging, potentially in part due to the effects of insulin resistance.

Epigenetic GrimAge acceleration and cognitive impairment in bipolar disorder

Bipolar disorder (BD) has been previously associated with clinical signs of premature aging, including accelerated epigenetic aging in blood and brain, and a steeper age-related decline in cognitive function. However, the clinical drivers and cognitive correlates of epigenetic aging in BD are still unknown. We aimed to investigate the relationship between multiple measures of epigenetic aging acceleration with clinical, functioning, and cognitive outcomes in patients with BD and controls. Blood genome-wide DNA methylation levels were measured in BD patients (n = 153) and matched healthy controls (n = 50) with the Infinium MethylationEPIC BeadChip (Illumina). Epigenetic age estimates were calculated using an online tool, including the recently developed lifespan predictor GrimAge, and analyzed with generalized linear models controlling for demographic variables and blood cell proportions. BD was significantly associated with greater GrimAge acceleration (AgeAccelGrim, β=0.197, p = 0.009), and significant group-dependent interactions were found between AgeAccelGrim and blood cell proportions (CD4+ T-lymphocytes, monocytes, granulocytes, and B-cells). Within patients, higher AgeAccelGrim was associated with worse cognitive function in multiple domains (short-term affective memory (β=-0.078, p = 0.030), short-term non-affective memory (β=-0.088, p = 0.018), inhibition (β=0.064, p = 0.046), and problem solving (β=-0.067, p = 0.034)), age of first diagnosis with any mood disorder (β=-0.076, p = 0.039) or BD (β=-0.102, p = 0.016), as well as with current non-smoking status (β=-0.392, p < 0.001). Overall, our findings support the contribution of epigenetic factors to the aging-related cognitive decline and premature mortality reported in BD patients, with an important driving effect of smoking in this population.

Early life adversity and age acceleration at mid-life and older ages indexed using the next-generation GrimAge and Pace of Aging epigenetic clocks

OBJECTIVE

This retrospective cross-sectional study was designed to explore whether the experience of childhood adversity was associated with epigenetic age acceleration in mid-life and older ages using the next generation GrimAge and Pace of Aging DNA methylation clocks.

METHOD

The study involved a sub-sample of 490 individuals aged 50-87 years of age participating in the Irish Longitudinal Study on Aging (TILDA); a large nationally representative prospective cohort study of aging in Ireland. Childhood adversity was ascertained via self-report using 5-items that were deemed to indicate potentially nefarious childhood exposures, including growing up poor, death of a parent, parental substance abuse in the family, childhood physical abuse, and childhood sexual abuse.

RESULTS

Only childhood poverty was associated with significant epigenetic age acceleration according to the GrimAge and Pace of Aging clocks, hastening biological aging by 2.04 years [CI= 1.07, 3.00; p < 0.001] and 1.16 years [CI= 0.11, 2.21; p = 0.030] respectively. Analysis of the dose-response pattern revealed each additional adversity was associated with 0.69 years of age acceleration [CI= 0.23, 1.15; p = 0.004] according to the GrimAge clock. Mediation analysis suggested that lifetime smoking explains a substantial portion (>50%) of the excess risk of age acceleration amongst those who experienced childhood poverty.

CONCLUSIONS

This study adds to the growing body of evidence which implicates early life adversity, particularly deprivation as a potential precipitant of earlier biological aging, and implicates smoking-related changes to DNA methylation processes as a candidate pathway and mechanism through which the social environment gets transduced at a biological level to hasten the aging process.

An epigenetic aging analysis of randomized metformin and weight loss interventions in overweight postmenopausal breast cancer survivors

Metformin and weight loss relationships with epigenetic age measures-biological aging biomarkers-remain understudied. We performed a post-hoc analysis of a randomized controlled trial among overweight/obese breast cancer survivors (N = 192) assigned to metformin, placebo, weight loss with metformin, or weight loss with placebo interventions for 6 months. Epigenetic age was correlated with chronological age (r = 0.20-0.86; P < 0.005). However, no significant epigenetic aging associations were observed by intervention arms. Consistent with published reports in non-cancer patients, 6 months of metformin therapy may be inadequate to observe expected epigenetic age deceleration. Longer duration studies are needed to better characterize these relationships.Trial Registration: Registry Name: ClincialTrials.Gov.Registration Number: NCT01302379.Date of Registration: February 2011.URL: https://clinicaltrials.gov/ct2/show/NCT01302379.

Are sex differences in cognitive impairment reflected in epigenetic age acceleration metrics?

Sex differences are well-established in Alzheimer's disease (AD) frequency and pathogenesis, but are not mechanistically understood. Accelerated epigenetic age has been associated with both cognitive aging and AD pathophysiology, but has not been studied by sex in AD or related cognitive impairment. Using the ADNI cohort, we found that none of sex, cognitive impairment diagnosis, nor load of APOEε4 alleles (strongest genetic AD risk factor) were associated with epigenetic age acceleration (DNAmAge, Intrinsic DNAmAge, PhenoAge, or GrimAge), although females exhibit more accelerated epigenetic aging using the Skin & Blood clock in the transition from normal cognition to cognitive impairment than males.

Associations of Age, Sex, Race/Ethnicity, and Education With 13 Epigenetic Clocks in a Nationally Representative U.S. Sample: The Health and Retirement Study

BACKGROUND

Many DNA methylation-based indicators have been developed as summary measures of epigenetic aging. We examine the associations between 13 epigenetic clocks, including 4 second generation clocks, as well as the links of the clocks to social, demographic, and behavioral factors known to be related to health outcomes: sex, race/ethnicity, socioeconomic status, obesity, and lifetime smoking pack-years.

METHODS

The Health and Retirement Study is the data source which is a nationally representative sample of Americans over age 50. Assessment of DNA methylation was based on the EPIC chip and epigenetic clocks were developed based on existing literature.

RESULTS

The clocks vary in the strength of their relationships with age, with each other and with independent variables. Second generation clocks trained on health-related characteristics tend to relate more strongly to the sociodemographic and health behaviors known to be associated with health outcomes in this age group.

CONCLUSIONS

Users of this publicly available data set should be aware that epigenetic clocks vary in their relationships to age and to variables known to be related to the process of health change with age.

Epigenetic Aging and Hematopoietic Cell Transplantation in Patients With Severe Aplastic Anemia

Cellular aging in hematopoietic cell transplantation (HCT) is important in the context of immune reconstitution and age-related complications. Recently, several DNA-methylation (DNAm)-based biomarkers of aging known as "epigenetic clocks" have been introduced as novel tools to predict cellular age. Here, we used Cox proportional hazards models to assess the possible associations of donor pre-HCT DNAm age, and its post-HCT changes, using the recently published lifespan-associated epigenetic clock known as "DNAm-GrimAge," with outcomes among patients with severe aplastic anemia (SAA). The study included 732 SAA patients from the Transplant Outcomes in Aplastic Anemia project, who underwent unrelated donor HCT and for whom a donor pre-HCT blood DNA sample was available; 41 also had a post-HCT sample collected at day 100. In multivariable analyses, we found similar associations for donor chronological age and pre-HCT DNAm-GrimAge with post-HCT survival (hazard ratio [HR] per decade = 1.13; 95% confidence interval [CI], 0.99-1.28; P = .07 and HR = 1.14; 95% CI, 0.99-1.28; P = .06, respectively). In donors with 10+ years of GrimAge acceleration (ie, deviation from expected DNAm age for chronological age), elevated risks of chronic graft versus host disease (HR = 2.4; 95% CI, 1.21-4.65; P = .01) and possibly post-HCT mortality (HR = 1.79; 95% CI, 0.96-3.33; P = .07) were observed. In the subset with post-HCT samples, we observed a significant increase in DNAm-GrimAge in the first 100 days after HCT (median change 12.5 years, range 1.4 to 26.4). Higher DNAm-GrimAge after HCT was associated with inferior survival (HR per year = 1.11; 95% CI, 1.02-1.21; P = .01), predominantly within the first year after HCT. This study highlights the possible role cellular aging may play in HCT outcomes.

Associations of DNA Methylation Mortality Risk Markers with Congenital Microcephaly from Zika Virus: A Study of Brazilian Children Less than 4 Years of Age

BACKGROUND

Zika virus (ZIKV)-associated congenital microcephaly is an important contributor to pediatric death, and more robust pediatric mortality risk metrics are needed to help guide life plans and clinical decision making for these patients. Although common etiologies of pediatric and adult mortality differ, early life health can impact adult outcomes-potentially through DNA methylation. Hence, in this pilot study, we take an early step in identifying pediatric mortality risk metrics by examining associations of ZIKV infection and associated congenital microcephaly with existing adult DNA methylation-based mortality biomarkers: GrimAge and Zhang's mortality score (ZMS).

METHODS

Mortality measures were calculated from previously published HumanMethylationEPIC BeadChip data from 44 Brazilian children aged 5-40 months (18 with ZIKV-associated microcephaly; 7 normocephalic, exposed to ZIKV in utero; and 19 unexposed controls). We used linear models adjusted for chronological age, sex, methylation batch and white blood cell proportions to evaluate ZIKV and mortality marker relationships.

RESULTS

We observed significant decreases in GrimAge-component plasminogen activator inhibitor-1 [PAI-1; β = -2453.06 pg/ml, 95% confidence interval (CI) -3652.96, -1253.16, p = 0.0002], and ZMS-site cg14975410 methylation (β = -0.06, 95% CI -0.09, -0.03, p = 0.0003) among children with microcephaly compared to controls. PAI-1 (β = -2448.70 pg/ml, 95% CI -4384.45, -512.95, p = 0.01) and cg14975410 (β = 0.01, 95% CI -0.04, 0.06, p = 0.64) results in comparisons of normocephalic, ZIKV-exposed children to controls were not statistically significant.

CONCLUSION

Our results suggest that elements of previously-identified adult epigenetic markers of mortality risk are associated with ZIKV-associated microcephaly, a known contributor to pediatric mortality risk. These findings may provide insights for efforts aimed at developing pediatric mortality markers.

Comparison of DNA methylation clocks in Black South African men

Aims: DNA methylation clocks are widely used to estimate biological age, although limited data are available on non-European ethnicities. This manuscript characterizes the behavior of five DNA methylation clocks in 120 older Black South African men. Methods: The age estimation accuracy of the Horvath, Hannum and skin and blood clocks and the relative age-related mortality risk and predicted time to death portrayed by the PhenoAge and GrimAge biomarkers are investigated, respectively. Results: The results confirm the tendency of DNA methylation clocks to underestimate the biological age of older individuals. GrimAge more accurately characterizes biological decline in this African cohort compared with PhenoAge owing to the unique inclusion of smoking-related damage in the GrimAge estimate. Conclusions: Each clock provides a different fraction of information regarding the aging body. It is essential to continue studying under-represented population groups to ensure methylation-derived indicators are robust and useful in all populations.

The influences of DNA methylation and epigenetic clocks, on metabolic disease, in middle-aged Koreans

Background

Considering that DNA methylation (DNAm) profiles are, in large part, modifiable by lifestyle and environmental influences, it has been proposed that epigenetic clocks provide a better estimate of biological age than chronological age, as associated with current health status. Even though metabolic diseases induce precocious aging, little is known about associations between metabolic syndrome (MetS) and DNA methylation clocks, and stochastic epigenetic mutations (SEMs), in a Korean population. Therefore, we assessed four different epigenetic clocks (Pan-tissue, Hannum, PhenoAge, and GrimAge), and their accelerations, on MetS and MetS-related lifestyle factors, in Koreans. We measured genome-wide DNA methylation (485,512 CpGs), using an Illumina 450 methylation BeadChip array, with data from 349 blood samples.

Results

DNAm GrimAge strongly correlated with chronological age (r = 0.77, p < 0.001) compared to the other three epigenetic clocks and SEMs. DNAm-based surrogate markers, with regard to MetS, including the gene encoding plasminogen activator inhibitor-1 (PAI1), also correlated with chronological age. Within cohorts stratified by age group, sex, regional area, smoking, and alcohol drinking, a positive correlation was observed between DNAm GrimAge and chronological age (0.43 ≤ r ≤ 0.78). In particular, we identified MetS to associate with accelerated GrimAge, and age-adjusted PAI1, in the middle-age group. Accerelated GrimAge also associated with risk of MetS in the middle-age group (odds ratio = 1.16, p = 0.046), which appears to mediate their associations with fasting glucose. Multiple linear regression showed that DNAm GrimAge, and its acceleration, associate with MetS scores, in the middle-age group (r = 0.26, p = 0.006). Age-adjusted PAI1 was also significantly different between the MetS and control groups, and further associated with MetS scores (r = 0.31, P < 0.001), in the middle age group.

Conclusion

DNAm GrimAge is a surrogate marker for MetS, and its component score, in Koreans. This association can be observed only in middle age. Therefore, appropriate DNA methylation clocks may aid in the prediction of Korean metabolic diseases.

The effects of social adversity, discrimination, and health risk behaviors on the accelerated aging of African Americans: Further support for the weathering hypothesis

BACKGROUND

The weathering hypothesis views the elevated rates of illness, disability, and mortality seen among Black Americans as a physiological response to the structural barriers, material hardships, and identity threats that comprise the Black experience. While granting that lifestyle may have some significance, the fundamental explanation for heath inequalities is seen as race-related stressors that accelerate biological aging.

OBJECTIVE

The present study tests the weathering hypothesis by examining the impact on accelerated aging of four types of adversity frequently experienced by Black Americans. Further, we investigate whether health risk behaviors mediate the effect of these conditions.

METHOD

Our analyses utilize data from 494 middle-age, African American men and women participating in the Family and Community Healthy Study. The newly developed GrimAge index of accelerated aging is used as an indicator of weathering. Education, income, neighborhood disadvantage, and discrimination serve as the independent variables. Three health risk behaviors - diet, exercise, and alcohol consumption - are included as potential mediators of the four types of adversity. Marital status and gender are entered as controls.

RESULTS

Multivariate analyses indicated that the four types of adversity predicted acceleration whereas marriage predicted deceleration in speed of aging. Males showed greater accelerated aging than females, but there was no evidence that gender conditioned the effect of adversity. The health risk behaviors were unrelated to accelerated aging and did not mediate the effect of the stressors.

CONCLUSION

Modern medicine's emphasis on life style as the primary explanation for race-based health disparities ignores the way race-related adversity rooted in structural and cultural conditions serves to accelerate biological decline, thereby increasing risk of early onset of illness and death. Importantly, these social conditions can only be addressed through social policies and programs that target institutional racism and promote economic equity.