Toxic stress history and hypothalamic-pituitary-adrenal axis function in a social stress task: Genetic and epigenetic factors

Associations between vicarious discrimination and mental health among young adult college students: Findings from the 2020-2021 Healthy Minds Study

BACKGROUND

Poor mental health among young adults in higher education is a growing concern. In recent years, the visibility of racism has sharply risen. Vicarious discrimination is defined as the secondhand witnessing of racism, and given society's increased accessibility to social media and the Internet, addressing indirect violence is urgently needed to inform anti-racism and mental health efforts. The current study examined associations between vicarious discrimination and mental health across a large sample of young college students in the United States.

METHODS

We analyzed data from the Healthy Minds Study (HMS; 2020-2021; N=130,566) and used multivariable logistic regression to examine whether past-year vicarious discrimination was associated with various mental health outcomes, adjusting for age, gender, race/ethnicity, and direct discrimination.

RESULTS

The sample was predominantly white (n=31,438, 63.66%) and female-identifying (n=34,313, 69.49%) with an average age of 21.1 years. Approximately 35.9% of the sample endorsed experiencing vicarious discrimination. Vicarious discrimination was associated with greater depression (OR:1.97; 95% CI: [1.86,2.09], p< 0.001), anxiety (OR:1.82; 95% CI: [1.72,1.92], p<0.001), languishing (OR:1.75; 95% CI: [1.65,1.87], p<0.001), perceived need for treatment (OR:2.24; 95% CI: [2.10,2.40], p<0.001), suicidal ideation (OR:1.86; 95% CI: [1.73,2.01], p<0.001), suicide plan (OR:1.91; 95% CI: [1.71,2.14], p<0.001), suicide attempt (OR:1.89; 95% CI: [1.51,2.36], p<0.001), self-injurious behavior (OR:2.0; 95% CI: [1.88,2.12], p<0.001), and loneliness (OR:1.67; 95% CI: [1.58,1.77], p<0.001).

DISCUSSION

Consistent with growing literature, vicarious discrimination was associated with poorer mental health among young college students. Additional research should investigate moderators, mediators, and interventions to support those who may be impacted indirectly by discrimination.

Sleep debt-induced anxiety and addiction to substances of abuse: A narrative review

Substance Use Disorder (SUD) has been conceptualized as an outcome of a dysregulated reward system. However, individuals with SUD suffer from anxiety with an intensity depending on the abstinence period length. This review discusses the role of anxiety as a major contributor to the initiation and perpetuation of SUD, and its dependence on an up-regulated defense-antireward system. In addition, it is discussed that sleep debt, and its psychosocial consequences, promote anxiety, contributing to SUD generation and maintenance. Healthy sleep patterns can be disrupted by diverse medical conditions and negative psychosocial interactions, resulting in accumulated sleep debt and anxiety. Within this narrative review, we discuss the interplay between the motivation-reward and defense-antireward systems, framing the progression from recreational drug use to addiction. This interplay is nuanced by sleep debt-induced anxiety and its psychosocial consequences as contributory vulnerability factors in the genesis of addiction.

A method for measuring mitochondrial DNA copy number in pediatric populations

The mitochondrion is a multifunctional organelle that modulates multiple systems critical for homeostasis during pathophysiological stress. Variation in mitochondrial DNA (mtDNA) copy number (mtDNAcn), a key mitochondrial change associated with chronic stress, is an emerging biomarker for disease pathology and progression. mtDNAcn can be quantified from whole blood samples using qPCR to determine the ratio of mtDNA to nuclear DNA. However, the collection of blood samples in pediatric populations, particularly in infants and young children, can be technically challenging, yield much smaller volume samples, and can be distressing for the patients and their caregivers. Therefore, we have validated a mtDNAcn assay utilizing DNA from simple buccal swabs (Isohelix SK-2S) and report here it's performance in specimens from infants (age = <12 months). Utilizing qPCR to amplify ∼200 bp regions from two mitochondrial (ND1, ND6) and two nuclear (BECN1, NEB) genes, we demonstrated absolute (100%) concordance with results from low-pass whole genome sequencing (lpWGS). We believe that this method overcomes key obstacles to measuring mtDNAcn in pediatric populations and creates the possibility for development of clinical assays to measure mitochondrial change during pathophysiological stress.

Investigating mitochondrial bioenergetics in peripheral blood mononuclear cells of women with childhood maltreatment from post-parturition period to one-year follow-up

BACKGROUND

Childhood maltreatment (CM) exerts various long-lasting psychological and biological changes in affected individuals, with inflammation being an interconnecting element. Besides chronic low-grade inflammation, CM might also affect the energy production of cells by altering the function and density of mitochondria, i.e. the body's main energy suppliers. Here, we compared mitochondrial respiration and density in intact peripheral blood mononuclear cells (PBMC), from women with and without CM between two time points, i.e. at the highly inflammatory phase within 1 week after parturition (t0) and again after 1 year (t2).

METHODS

CM exposure was assessed with the Childhood Trauma Questionnaire. Whole blood was collected from n = 52 healthy women within the study 'My Childhood - Your Childhood' at both time points to isolate and cryopreserve PBMC. Thawed PBMC were used to measure mitochondrial respiration and density by high-resolution respirometry followed by spectrophotometric analyses of citrate-synthase activity.

RESULTS

Over time, quantitative respiratory parameters increased, while qualitative flux control ratios decreased, independently of CM. Women with CM showed higher mitochondrial respiration and density at t0, but not at t2. We found significant CM group × time interaction effects for ATP-turnover-related respiration and mitochondrial density.

CONCLUSIONS

This is the first study to longitudinally investigate mitochondrial bioenergetics in postpartum women with and without CM. Our results indicate that CM-related mitochondrial alterations reflect allostatic load, probably due to higher inflammatory states during parturition, which normalize later. However, later inflammatory states might moderate the vulnerability for a second-hit on the level of mitochondrial bioenergetics, at least in immune cells.

N6-methyladenosine(m6A) demethylase FTO regulates cellular apoptosis following cobalt-induced oxidative stress

Cobalt is an environmental toxicant that is known to damage human health. However, the molecular mechanisms underlying cobalt-induced neurotoxicity have not been elucidated in detail. In the present research, we used human neuroglioma H4 cells as an in vitro model. Cells were exposed to CoCl₂ (0, 100, 200, 400 μM) for 24 h. We performed m⁶A sequencing techniques and constructed FTO-knockdown/FTO-overexpressing cells to investigate the role of FTO-mediated m⁶A modification in regulating apoptosis following CoCl₂ induced oxidative stress. Our study has shown CoCl₂ exposure led to the decrease of demethylase FTO as well as elevated oxidative stress. However, NAC treatment could partly reverse the reduction of FTO expression as well as the degree of ROS via eliminating oxidative stress. Meanwhile, MeRIP-seq and RNA-seq further revealed the potential function m⁶A modification in regulating apoptosis. More importantly, KEGG pathway and Gene ontology (GO) analyses further elucidated that the differentially m⁶A-modified genes were aggregated in apoptosis-related pathways. Mechanistic analysis indicated that knockdown of FTO facilitated CoCl₂-induced apoptosis via caspase activation and G1/S cell cycle arrest. Nevertheless, overexpression of FTO partly attenuated the increased apoptosis following CoCl₂ exposure. More notably, we observed that FTO regulated apoptosis in an m⁶A-dependent manner. Therefore, our findings reveal that CoCl₂ induced ROS affected the m⁶A modification of apoptosis-related genes by decreasing the expression of FTO, thereby resulting in the activation of apoptosis. These findings provide important insights into CoCl₂-induced apoptosis and m⁶A modification and propose a novel strategy for studying environmental toxicant-related neurodegeneration.

Transposable Elements and Human Diseases: Mechanisms and Implication in the Response to Environmental Pollutants

Transposable elements (TEs) are recognized as major players in genome plasticity and evolution. The high abundance of TEs in the human genome, especially the Alu and Long Interspersed Nuclear Element-1 (LINE-1) repeats, makes them responsible for the molecular origin of several diseases. This involves several molecular mechanisms that are presented in this review: insertional mutation, DNA recombination and chromosomal rearrangements, modification of gene expression, as well as alteration of epigenetic regulations. This literature review also presents some of the more recent and/or more classical examples of human diseases in which TEs are involved. Whether through insertion of LINE-1 or Alu elements that cause chromosomal rearrangements, or through epigenetic modifications, TEs are widely implicated in the origin of human cancers. Many other human diseases can have a molecular origin in TE-mediated chromosomal recombination or alteration of gene structure and/or expression. These diseases are very diverse and include hemoglobinopathies, metabolic and neurological diseases, and common diseases. Moreover, TEs can also have an impact on aging. Finally, the exposure of individuals to stresses and environmental contaminants seems to have a non-negligible impact on the epigenetic derepression and mobility of TEs, which can lead to the development of diseases. Thus, improving our knowledge of TEs may lead to new potential diagnostic markers of diseases.

Theory of mind and hair cortisol in healthy young adults: the moderating effects of childhood trauma

Background: Experiences of negative social interactions and childhood trauma (CT) can lead to aberrant hypothalamic-pituitary-adrenal functions. Poor theory of mind (ToM) ability is related to increased social stress levels; however, studies on the relationship between ToM and cortisol remain scarce. Objective: This study aimed to evaluate the relationship between ToM and the hair cortisol concentration (HCC) in healthy young adults considering the moderating role of CT. Method: A total of 206 healthy young adults were divided into two groups based on an experience of moderate-to-severe childhood trauma (CT+ and CT-). To determine whether CT moderated the relationship between ToM and HCC, moderation analysis was conducted controlling for age, sex, years of education, and scores of perceived stress, depression, and anxiety. Results: CT+ individuals reported higher subjective stress perception and depressive symptoms than CT- individuals, whereas anxiety-related symptoms, ToM, and HCC were not different between the groups. The experience of CT significantly moderated the relationship between ToM and HCC. The association between poorer ToM ability and higher HCC was significant only in CT+ group. Conclusion: CT is a moderator of the association between ToM and HCC, indicating the importance of CT in social cognition and the stress response.

Strategies to improve diversity, equity, and inclusion in clinical trials

There is a growing need for diversity, equity, and inclusion (DEI) in cancer care, particularly with respect to equal access and accrual to clinical trials. This commentary describe steps taken to address disparities in the authors' own clinical practice and proposes actions at the patient, provider, community, and institution levels to improve DEI in clinical trials.

Neurobiological mechanisms of early life adversity, blunted stress reactivity and risk for addiction

Blunted stress reactivity resulting from early exposure to stress during childhood and adolescence may increase vulnerability to addiction. Early life adversity (ELA) affects brain structure and function and results in blunted stress axis reactivity. In this review, we focus on the underlying neurobiological mechanisms associated with a blunted response to stress, ELA, and risk for addictive disorders. ELA and blunted reactivity are accompanied by unstable mood regulation, impulsive behaviors, and reduced cognitive function. Neuroimaging studies reveal cortical and subcortical changes in persons exposed to ELA and those who have a genetic disposition for addiction. We propose a model in which blunted stress reactivity may be a marker of risk for addiction through an altered motivational and behavioral reactivity to stress that contribute to disinhibited behavioral reactivity and impulsivity leading in turn to increased vulnerability for substance use. Evidence supporting this hypothesis in the context of substance use initiation, maintenance, and risk for relapse is presented. The effects of ELA on persons at risk for addiction may lead to early experimentation with drugs of abuse. Early adoption of drug intake may alter neuroregulation in such vulnerable persons leading to a permanent dysregulation of motivational responses consistent with dependence. This article is part of the special issue on 'Vulnerabilities to Substance Abuse'.

A systematic review of childhood maltreatment and DNA methylation: candidate gene and epigenome-wide approaches

Childhood maltreatment is a major risk factor for chronic and severe mental and physical health problems across the lifespan. Increasing evidence supports the hypothesis that maltreatment is associated with epigenetic changes that may subsequently serve as mechanisms of disease. The current review uses a systematic approach to identify and summarize the literature related to childhood maltreatment and alterations in DNA methylation in humans. A total of 100 empirical articles were identified in our systematic review of research published prior to or during March 2020, including studies that focused on candidate genes and studies that leveraged epigenome-wide data in both children and adults. Themes arising from the literature, including consistent and inconsistent patterns of results, are presented. Several directions for future research, including important methodological considerations for future study design, are discussed. Taken together, the literature on childhood maltreatment and DNA methylation underscores the complexity of transactions between the environment and biology across development.

Genetic and Epigenetic Consequence of Early-Life Social Stress on Depression: Role of Serotonin-Associated Genes

Early-life adversity caused by poor social bonding and deprived maternal care is known to affect mental wellbeing and physical health. It is a form of chronic social stress that persists because of a negative environment, and the consequences are long-lasting on mental health. The presence of social stress during early life can have an epigenetic effect on the body, possibly resulting in many complex mental disorders, including depression in later life. Here, we review the evidence for early-life social stress-induced epigenetic changes that modulate juvenile and adult social behavior (depression and anxiety). This review has a particular emphasis on the interaction between early-life social stress and genetic variation of serotonin associate genes including the serotonin transporter gene (5-HTT; also known as SLC6A4), which are key molecules involved in depression.

Examining the role of ethnic microaggressions and ethnicity on cortisol responses to an acute stressor among young adults

Objective: This study examined whether the frequency of experiences of ethnic microaggressions and the sensitivity to such experiences were associated with cortisol responses to an acute social stressor (Trier Social Stress Test; TSST) among an ethnically diverse sample of young adults (N = 109, Mage = 18.82 years, SD = 1.40 years, 74% female, 44% Latinx). Method: Self-reported experiences of and sensitivity to microaggressions were assessed using the Everyday Microaggressions Scale. Participants' salivary cortisol was collected before, immediately after, and at three 15-min intervals after the TSST (for a total of 5 salivary samples) to assess their cortisol responses to an acute social stressor. Results: Mixed model analyses revealed that experiencing a higher frequency of microaggressions (p = .005) and being more sensitive to those experiences (p = .001) were associated with a more blunted cortisol response (i.e., lower cortisol reactivity and recovery) to the TSST, relative to experiencing a lower frequency of microaggressions and being less sensitive to them. Furthermore, this blunted cortisol response to the TSST was more prominent among young adults of Latinx and other ethnic backgrounds (i.e., biracial, African American, and Native American) compared to their Asian American and non-Hispanic White peers (p = .034). Conclusion: Findings provide insight into the different ways in which experiences of ethnic microaggressions can be associated with biological markers of stress. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Offensive Behavior, Striatal Glutamate Metabolites, and Limbic-Hypothalamic-Pituitary-Adrenal Responses to Stress in Chronic Anxiety

Variations in anxiety-related behavior are associated with individual allostatic set-points in chronically stressed rats. Actively offensive rats with the externalizing indicators of sniffling and climbing the stimulus and material tearing during 10 days of predator scent stress had reduced plasma corticosterone, increased striatal glutamate metabolites, and increased adrenal 11-dehydrocorticosterone content compared to passively defensive rats with the internalizing indicators of freezing and grooming, as well as to controls without any behavioral changes. These findings suggest that rats that display active offensive activity in response to stress develop anxiety associated with decreased allostatic set-points and increased resistance to stress.

Molecular correlates of mitochondrial dysfunctions in major depression: Evidence from clinical and rodent studies

Major depressive disorder (MDD) is one of the most prevalent stress-related mental disorders worldwide. Several biological mechanisms underlying the pathophysiology of MDD have been proposed, including endocrine disturbances, neurotransmitter deficits, impaired neuronal plasticity, and more recently, mitochondrial dysfunctions. In this review, we provide an overview of relevant molecular correlates of mitochondrial dysfunction in MDD, based on findings from clinical studies and stress-induced rodent models. We also compare differences and similarities between the phenotypes of MDD patients and animal models. Our analysis of the literature reveals that both MDD and stress are associated, in humans and animals, with changes in mitochondrial biogenesis, redox imbalance, increased oxidative damages of cellular macromolecules, and apoptosis. Yet, a considerable amount of conflicting data exist and therefore, the translation of findings from clinical and preclinical research to novel therapies for MDD remains complex. Further studies are needed to advance our understanding of the molecular networks and biological mechanisms involving mitochondria in the pathophysiology of MDD.

Epigenetic mechanisms activated by childhood adversity

Adverse childhood experiences (ACE) impair health and life expectancy and may result in an epigenetic signature that drives increased morbidity primed during early stages of life. This literature review focuses on the current evidence for epigenetic-mediated programming of brain and immune function resulting from ACE. To address this aim, a total of 88 articles indexed in PubMed before August 2019 concerning ACE and epigenetics were surveyed. Current evidence partially supports epigenetic programming of the hypothalamic-pituitary-adrenal axis, but convincingly shows that ACE impairs immune function. Additionally, the needs and challenges that face this area are discussed in order to provide a framework that may help to clarify the role of epigenetics in the long-lasting effects of ACE.

Discrimination Increases the Association Between Parental and Adolescent Allostatic Load in Chinese Rural-to-Urban Migrants

PURPOSE

This study was designed to examine the extent to which parents' allostatic load (AL) and adolescents' perceived discrimination are interrelated in the prediction of adolescents' AL among rural-to-urban migrants in China, as well as the possible buffering role of social support.

METHODS

Multi-informant data were collected in this study. A total of 158 rural-to-urban migrant adolescents (Mean_age = 11.62 years) and one of each of their parents (Mean_age = 39.84 years) were recruited from the suburbs of Beijing, China. Both adolescents' and parents' AL scores were based on 10 physiological indices. Migrant adolescents were asked to report their perceived discrimination and social support.

RESULTS

Parents' AL was significantly positively related to adolescents' AL. The relationship between parents' and adolescents' AL was stronger among adolescents reporting higher perceived discrimination than among those reporting lower. Social support moderated the adverse effects of parents' AL and perceived discrimination on adolescents' AL. Specifically, among adolescents reporting higher social support, the relationships between parents' and adolescents' AL were not significant for those with either high or low perceived discrimination. However, among adolescents reporting lower social support, the positive association was significant for those with high perceived discrimination but not for those with low perceived discrimination.

CONCLUSIONS

Parents' AL was a strong predictor of migrant adolescents' AL, and perceived discrimination acted as a catalyst to increase the association. The relationships of parental AL and perceived discrimination with AL were not significant for adolescents who received high social support.

Minimally-invasive methods for examining biological changes in response to chronic stress: A scoping review

BACKGROUND

Nurse researchers are increasingly interested in incorporating biological indicators related to chronic stress, or repeated or constant exposure to psychological stressors. Minimally invasive collection methods may improve access to vulnerable populations.

OBJECTIVE

To map biological indicators measured through minimally invasive methods investigating biological changes in response to chronic stress.

DESIGN, DATA SOURCES, AND METHODS

The paper seeks to answer two questions: What are the characteristics of the minimally-invasive methods used to measure the biological correlates of chronic stress? What are the limitations regarding the use of the minimally-invasive methods and/or biological indicators identified above? Authors completed a scoping review following guidelines from the Joanna Briggs Institute Manual and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for Scoping Reviews. A literature search was completed in PubMed, PsycINFO, and Scopus. 2518 articles were screened and 145 studies were included. Data were extracted using a standardized extraction tool, compiled, and coded.

RESULTS

Studies included minimally-invasive methods to measure the hypothalamic-adrenal-pituitary axis (N = 173), immune and inflammatory markers (N = 118), and adult neurogenesis (N = 6). Cortisol was most frequently measured (N = 136), usually in saliva (N = 86). Studies included a variety of limitations for the methods and indicators, including concerns about timing and accuracy of collection, frequency of sampling, and controlling for acute stressors.

CONCLUSIONS

Nurse researchers have access to many minimally-invasive methods to measure altered biological processes related to chronic stress. A gap identified by this review is the paucity of minimally-invasive methods for investigating neurogenesis; the measurement of brain derived neurotrophic factor in plasma is a distal proxy and further research is needed to test the response of peripheral levels to psychosocial stress interventions. Additionally, while this scoping review allows nurse researchers to consider possible biological indicators to include in their research, future research is still needed on some of the basic premises of stress research, including agreement on the conceptualization of chronic stress.

Extending the toxic stress model into adolescence: Profiles of cortisol reactivity

The toxic stress model posits that extended activation of stress response systems in the absence of a supportive relationship with an adult may over time lead to physiological alterations to these same systems, and ultimately to poorer physical and mental health outcomes. However, empirical tests of model hypotheses in adolescence, a critical period of development, are lacking. This study expands the toxic stress model to include more developmentally-appropriate risk and protective factors for adolescents experiencing overwhelming and uncontrollable stressors. Data were collected for a study of early adolescents from urban low-income households (N = 101; 10-12 years old; 59% female). Participants and a caregiver completed questionnaires; youths completed the modified Trier Social Stress Task alone and provided six saliva samples. Using latent profile analysis, three profiles of cortisol reactivity were identified in early adolescents exposed to chronic environmental stress: Elevated and Reactive (11%), Moderate and Non-Reactive (26%), and Blunted and Non-Reactive (63%). In accordance with the toxic stress model, exposure to more community violence and less family support were associated with blunted cortisol reactivity, and Reactive profile membership was associated with fewer trauma symptoms. Overall, the findings provide empirical support for the extension of the toxic stress model in early adolescence through the application of developmentally-sensitive measures and provide implications for future interventions.

Epigenomic mediation after adverse childhood experiences: a systematic review and meta-analysis

Epigenetic mechanisms are potential mediators of the physiological response to abuse by altering the genetic predisposition of the cellular response to the environment, leading to changes in the regulation of multiple organ systems. This study was established to review the epigenetic mechanisms associated with childhood abuse as well as the long-term determinants that these epigenetic changes may have on future illness. We retrospectively analysed the effect of exposure to adverse childhood experiences (ACEs, specifically those relating to childhood maltreatment) between the ages of 0 and 16 years on the human epigenome, as well as possible clinical associations. After meeting inclusion and exclusion criteria, 36 articles were included in this systematic review. Eight of these studies did not find a relationship between childhood maltreatment and DNA methylation. Of the remaining 28 studies, nine were genome-wide association studies, whereas the rest were candidate gene studies, mainly studying effects on neuroendocrine, serotoninergic and immunoregulatory systems. Meta-analysis of correlation coefficients from candidate gene studies estimated an association of childhood adversity and DNA methylation variation at r = 0.291 (P < 0.0001), and meta-analysis of two epigenome-wide association studies (EWASs) identified 44 differentially methylated CpG sites. In conclusion, childhood maltreatment may mediate epigenetic mechanisms through DNA methylation, thereby affecting physiological responses and conferring a predisposition to an increased risk for psychopathology and forensic repercussions. Similar evidence for somatic illnesses is not yet available.

KEY POINTS

Adverse childhood experiences are associated with increased mortality partly explained by acquired epigenetic changes

There is a positive correlation between childhood abuse and DNA methylation at specific gene sites

The cumulative effect of different types of childhood abuse and neglect may lead to changes in DNA methylation

Epigenome changes associated with childhood abuse appear to be involved in the development of psychiatric illness in adulthood

Studying epigenetic changes may have important public health and forensic applications in the future

Early life exposures, neurodevelopmental disorders, and transposable elements

Transposable elements make up a much larger portion of the genome than protein-coding genes, yet we know relatively little about their function in the human genome. However, we are beginning to more fully understand their role in brain development, neuroinflammation, and adaptation to environmental insults such as stress. For instance, glucocorticoid receptor activation regulates transposable elements in the brain following acute stress. Early life is a period of substantial brain development during which transposable elements play a role. Environmental exposures and experiences during early life that promote abnormal regulation of transposable elements may lead to a cascade of events that ultimately increase susceptibility to disorders later in life. Recent attention to transposable elements in psychiatric illness has begun to clarify associations indicative of dysregulation of different classes of transposable elements in stress-related and neurodevelopmental illness. Though individual susceptibility or resiliency to psychiatric illness has not been explained by traditional genetic studies, the wide inter-individual variability in transposable element composition in the human genome make TEs attractive candidates to elucidate this differential susceptibility. In this review, we discuss evidence that regulation of transposable elements in the brain are stage-specific, sensitive to environmental factors, and may be impacted by early life perturbations. We further present evidence of associations with stress-related and neurodevelopmental psychiatric illness from a developmental perspective.

Blunted stress reactivity reveals vulnerability to early life adversity in young adults with a family history of alcoholism

BACKGROUND AND AIMS

People with blunted stress reactivity have poor impulse control and also show increased risk for alcoholism. Exposure to early life adversity (ELA) contributes to blunted reactivity, but individual differences in susceptibility to ELA are not well understood. This study aimed to determine whether exposure to ELA has a greater impact on stress reactivity in young adults with a family history of alcoholism (FH+) compared with young adults with no family history of alcoholism (FH-).

DESIGN

Observational study using linear modeling.

SETTING

Oklahoma, USA.

PARTICIPANTS

Seven hundred and nine young adults (398 females) recruited through community advertisement.

MEASUREMENTS

We obtained heart rates and cortisol levels in subjects while undergoing public speaking and mental arithmetic stress compared with a resting control day (1418 test sessions). ELA was quantified as 0, 1 or > 1 adverse events experienced by age 15 years. FH+ people had one or two parents with an alcohol use disorder, and FH- controls had no such history for two generations.

FINDINGS

Increasing levels of ELA predicted progressive blunting of cortisol and heart rate reactivity for the whole sample (Fs = 4.57 and 4.70, Ps ≤ 0.011), but examination by FH status showed that the effect of ELA was significant only among FH+ (Fs ≥ 3.5, Ps < 0.05) and absent in FH- (Ps > 0.40). This difference in ELA impact was not explained by the cortisol diurnal cycle or subjective evaluation of the stressors.

CONCLUSIONS

People with a family history of alcoholism appear to be vulnerable, in terms of changes to physiological stress response, to the impact of exposure to early life adversity while people with no family history of alcoholism appear to be resilient. Blunted stress reactivity may reflect differential vulnerability to early life adversity in young adults with a family history of alcoholism.

The Mitochondrion as Potential Interface in Early-Life Stress Brain Programming

Mitochondria play a central role in cellular energy-generating processes and are master regulators of cell life. They provide the energy necessary to reinstate and sustain homeostasis in response to stress, and to launch energy intensive adaptation programs to ensure an organism’s survival and future well-being. By this means, mitochondria are particularly apt to mediate brain programming by early-life stress (ELS) and to serve at the same time as subcellular substrate in the programming process. With a focus on mitochondria’s integrated role in metabolism, steroidogenesis and oxidative stress, we review current findings on altered mitochondrial function in the brain, the placenta and peripheral blood cells following ELS-dependent programming in rodents and recent insights from humans exposed to early life adversity (ELA). Concluding, we propose a role of the mitochondrion as subcellular intersection point connecting ELS, brain programming and mental well-being, and a role as a potential site for therapeutic interventions in individuals exposed to severe ELS.

Looking back and moving forward: Evaluating and advancing translation from animal models to human studies of early life stress and DNA methylation

Advances in epigenetic methodologies have deepened theoretical explanations of mechanisms linking early life stress (ELS) and disease outcomes and suggest promising targets for intervention. To date, however, human studies have not capitalized on the richness of diverse animal models to derive and systematically evaluate specific and testable hypotheses. To promote cross-species dialog and scientific advance, here we provide a classification scheme to systematically evaluate the match between characteristics of human and animal studies of ELS and DNA methylation. Three preclinical models were selected that are highly cited, and that differ in the nature and severity of the ELS manipulation as well as in the affected epigenetic loci (the licking and grooming, maternal separation, and caregiver maltreatment models). We evaluated the degree to which human studies matched these preclinical models with respect to the timing of ELS and of DNA methylation assessment, as well as the type of ELS, whether sex differences were explicitly examined, the tissue sampled, and the targeted loci. Results revealed <50% match (range of 8-83%) between preclinical models and human work on these variables. Immediate and longer-term suggestions to improve translational specificity are offered, with the goal of accelerating scientific advance.