Early life adversity increases the salience of later life stress: an investigation of interactive effects in the PSID

Exposure to elevated glucocorticoid during development primes altered transcriptional responses to acute stress in adulthood

Early life stress (ELS) is a major risk factor for developing psychiatric disorders, with glucocorticoids (GCs) implicated in mediating its effects in shaping adult phenotypes. In this process, exposure to high levels of developmental GC (hdGC) is thought to induce molecular changes that prime differential adult responses. However, identities of molecules targeted by hdGC exposure are not completely known. Here, we describe lifelong molecular consequences of hdGC exposure using a newly developed zebrafish double-hit stress model, which shows altered behaviors and stress hypersensitivity in adulthood. We identify a set of primed genes displaying altered expression only upon acute stress in hdGC-exposed adult fish brains. Interestingly, this gene set is enriched in risk factors for psychiatric disorders in humans. Lastly, we identify altered epigenetic regulatory elements following hdGC exposure. Thus, our study provides comprehensive datasets delineating potential molecular targets mediating the impact of hdGC exposure on adult responses.

Early-life stress alters chromatin modifications in VTA to prime stress sensitivity

Early-life stress increases sensitivity to subsequent stress, which has been observed among humans, other animals, at the level of cellular activity, and at the level of gene expression. However, the molecular mechanisms underlying such long-lasting sensitivity are poorly understood. We tested the hypothesis that persistent changes in transcription and transcriptional potential were maintained at the level of the epigenome, through changes in chromatin. We used a combination of bottom-up mass spectrometry, viral-mediated epigenome-editing, behavioral quantification, and RNA-sequencing in a mouse model of early-life stress, focusing on the ventral tegmental area (VTA), a brain region critically implicated in motivation, reward learning, stress response, and mood and drug disorders. We find that early-life stress in mice alters histone dynamics in VTA and that a majority of these modifications are associated with an open chromatin state that would predict active, primed, or poised gene expression, including enriched histone-3 lysine-4 methylation and the H3K4 monomethylase Setd7. Mimicking ELS through over-expression of Setd7 and enrichment of H3K4me1 in VTA recapitulates ELS-induced behavioral and transcriptional hypersensitivity to future stress. These findings enrich our understanding of the epigenetic mechanisms linking early-life environmental experiences to long-term alterations in stress reactivity within the brain's reward circuitry, with implications for understanding and potentially treating mood and anxiety disorders in humans.

Stress, Environment and Early Psychosis

Existing literature provides extended evidence of the close relationship between stress dysregulation, environmental insults, and psychosis onset. Early stress can sensitize genetically vulnerable individuals to future stress, modifying their risk for developing psychotic phenomena. Neurobiological substrate of the aberrant stress response to hypothalamic-pituitary-adrenal axis dysregulation, disrupted inflammation processes, oxidative stress increase, gut dysbiosis, and altered brain signaling, provides mechanistic links between environmental risk factors and the development of psychotic symptoms. Early-life and later-life exposures may act directly, accumulatively, and repeatedly during critical neurodevelopmental time windows. Environmental hazards, such as pre- and perinatal complications, traumatic experiences, psychosocial stressors, and cannabis use might negatively intervene with brain developmental trajectories and disturb the balance of important stress systems, which act together with recent life events to push the individual over the threshold for the manifestation of psychosis. The current review presents the dynamic and complex relationship between stress, environment, and psychosis onset, attempting to provide an insight into potentially modifiable factors, enhancing resilience and possibly influencing individual psychosis liability.

Caregivers of People With Mild Cognitive Impairment and Dementia: Characterizing Social and Psychological Outcomes

OBJECTIVE

Little is known about caregiving across the spectrum of cognitive impairment [mild cognitive impairment (MCI) to dementia] and how early life and sociocultural factors affect caregiver health. In this study, we characterized differences between caregivers of those with MCI versus those with dementia.

METHODS

A total of 158 caregivers were enrolled in this cross-sectional study, most of whom were dementia caregivers (65%). Caregivers completed questionnaires on depressive symptoms, self-rated health (SRH), perceived burden and stress, as well as psychosocial and demographic measures.

RESULTS

Caregivers of those with MCI reported fewer depressive symptoms and lower stress and burden compared with dementia caregivers. In adjusted analyses caregivers with greater stress reported more depressive symptoms. For SRH, at lower stress levels, having a sibling die before age 18 (ie, early life adversity) was associated with poorer SRH; at higher stress levels, having early life adversity was associated with better SRH. At lower burden levels, more live births were associated with worse SRH; at higher burden levels, more live births were associated with better SRH.

CONCLUSIONS

Early life factors are relevant for caregivers of those with cognitive impairment and targeted prevention and early intervention may be helpful in alleviating caregiver burden and stress.

Reactivation of Early-Life Stress-Sensitive Neuronal Ensembles Contributes to Lifelong Stress Hypersensitivity

Early-life stress (ELS) is one of the strongest lifetime risk factors for depression, anxiety, suicide, and other psychiatric disorders, particularly after facing additional stressful events later in life. Human and animal studies demonstrate that ELS sensitizes individuals to subsequent stress. However, the neurobiological basis of such stress sensitization remains largely unexplored. We hypothesized that ELS-induced stress sensitization would be detectable at the level of neuronal ensembles, such that cells activated by ELS would be more reactive to adult stress. To test this, we leveraged transgenic mice to genetically tag, track, and manipulate experience-activated neurons. We found that in both male and female mice, ELS-activated neurons within the nucleus accumbens (NAc), and to a lesser extent the medial prefrontal cortex, were preferentially reactivated by adult stress. To test whether reactivation of ELS-activated ensembles in the NAc contributes to stress hypersensitivity, we expressed hM4Dis receptor in control or ELS-activated neurons of pups and chemogenetically inhibited their activity during experience of adult stress. Inhibition of ELS-activated NAc neurons, but not control-tagged neurons, ameliorated social avoidance behavior following chronic social defeat stress in males. These data provide evidence that ELS-induced stress hypersensitivity is encoded at the level of corticolimbic neuronal ensembles.SIGNIFICANCE STATEMENT Early-life stress enhances sensitivity to stress later in life, yet the mechanisms of such stress sensitization are largely unknown. Here, we show that neuronal ensembles in corticolimbic brain regions remain hypersensitive to stress across the life span, and quieting these ensembles during experience of adult stress rescues stress hypersensitivity.

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.

Impact of Early Life Stress on Reward Circuit Function and Regulation

Early life stress - including experience of child maltreatment, neglect, separation from or loss of a parent, and other forms of adversity - increases lifetime risk of mood, anxiety, and substance use disorders. A major component of this risk may be early life stress-induced alterations in motivation and reward processing, mediated by changes in the nucleus accumbens (NAc) and ventral tegmental area (VTA). Here, we review evidence of the impact of early life stress on reward circuit structure and function from human and animal models, with a focus on the NAc. We then connect these results to emerging theoretical models about the indirect and direct impacts of early life stress on reward circuit development. Through this review and synthesis, we aim to highlight open research questions and suggest avenues of future study in service of basic science, as well as applied insights. Understanding how early life stress alters reward circuit development, function, and motivated behaviors is a critical first step toward developing the ability to predict, prevent, and treat stress-related psychopathology spanning mood, anxiety, and substance use disorders.

Adverse Childhood Experiences and Physical and Mental Health of Adults: Assessing the Mediating Role of Cumulative Life Course Poverty

OBJECTIVES

Research has linked adverse childhood experiences (ACEs) to a host of negative health outcomes in adulthood. However, most existing studies focused on traumatic ACEs and used samples collected from a specific geographic unit (e.g., region, city, or state). This study examines the association between non-traumatic ACEs and health outcomes (i.e., self-rated health and psychological well-being) in adulthood, and assesses the extent to which the cumulative life course poverty accounts for these associations between ACEs and health.

DATA SOURCE

Public and de-identified data from Panel Study of Income Dynamics (PSID) (1968-2013) and its Childhood Retrospective Circumstances Study (CRCS) (2014) (N = 7,126) were used. Episode and severity of childhood adversities of respondents were determined by using comprehensive retrospective circumstance measures.

METHODS

Multivariate regression models were used to analyze the associations between ACEs and adult health. Mediation analysis was employed to assess the extent to which the associations were explained by cumulative life course poverty. Data analysis was carried out in 2019 using STATA 15.

RESULTS

We found that episode and severity of ACEs were associated with increased risk of poor health and psychological distress. Compared to individuals with no ACEs, one unit increase in the ACE index is associated with 8 and 18 percent increase in the risk of poor health and psychological distress, respectively. A small proportion (4%) of the impact of early adversities on health is attributable to the proportion of adult lifetime spent in poverty.

CONCLUSIONS

Non-traumatic ACEs are associated with increased risk for poor health and psychological distress. Life course cumulative experience in poverty accounts for a small portion of the associations. Providing support to prevent ACEs may have long-term health benefits.