Early life adversity: Lasting consequences for emotional learning

Unraveling the influence of childhood emotional support on adult aging: Insights from the UK Biobank

BACKGROUND

Exploring the association between Childhood Emotional Support (CES) and the mechanisms of aging is pivotal for understanding its potential to lessen the incidence of age-related pathologies and promote a milieu for healthy aging.

METHODS

Utilizing data from the UK Biobank comprising nearly 160,000 individuals, comprehensive analyses were conducted to explore associations between CES levels and age-related diseases, biological age and aging hallmarks. Cox proportional hazards regression models were used to investigate the relationship between CES and the risk of hospitalization for age-related diseases. Linear regression models were employed to explore the associations between CES and the frailty index (FI), Klemera-Doubal method (KDM) biological age acceleration, homeostatic dysregulation (HD), C-reactive protein (CRP), white blood cell (WBC) count, and telomere length.

RESULTS

The analyses revealed a significant association between higher CES levels and a decreased risk of hospitalization for age-related diseases in later life. After adjustments for covariates, the hazard ratio for age-related diseases was 0.87 (95 % confidence interval, 0.83-0.91, p < 0.001) in those with the highest CES level compared to those with the lowest CES level. Participants with the highest CES level exhibited lower FI scores (coefficient = -0.033, p < 0.001), reduced CRP level (coefficient = -0.097, p < 0.05) and lower WBC counts (coefficient = -0.034, p < 0.05). Stratified analyses based on genetic susceptibility further elucidated the protective role of CES against age-related diseases.

CONCLUSION

These findings underscore the potential of early interventions targeting CES to promote healthy aging and alleviating the burden of age-related diseases.

Impacts of early life adversity on the neurocircuitry of emotional memory in children

Similar to adults with posttraumatic stress disorder, children with early life adversity show bias in memory for negative emotional stimuli. However, it is not well understood how childhood adversity impacts mechanisms underlying emotional memory. N = 56 children (8-14 years, 48% female) reported on adverse experiences including potentially traumatic events and underwent fMRI while attending to emotionally pleasant, neutral, or negative images. Post-scan, participants completed a cued recall test to assess memory for these images. Emotional difference-in-memory (DM) scores were computed by subtracting negative or positive from neutral recall performance. All children showed enhancing effects of emotion on recall, with no effect of trauma load. However, children with less trauma showed a larger emotional DM for both positive and negative stimuli when amygdala or anterior hippocampal activity was higher. In contrast, highly trauma-exposed children demonstrated a lower emotional DM with greater amygdala or hippocampal activity. This suggested that alternative neural mechanisms might support emotional enhancement of encoding in children with greater trauma load. Whole-brain analyses revealed that right fusiform activity during encoding positively correlated with both trauma load and successful later recall of positive images. Therefore, highly trauma-exposed children may use alternative, potentially adaptive neural pathways via the ventral visual stream to encode positive emotional events.

Early-life risperidone alters locomotor responses to apomorphine and quinpirole in adulthood

An escalating trend of antipsychotic drug use in children with ADHD, disruptive behavior disorder, or mood disorders has raised concerns about the impact of these drugs on brain development. Since antipsychotics chiefly target dopamine receptors, it is important to assay the function of these receptors after early-life antipsychotic administration. Using rats as a model, we examined the effects of early-life risperidone, the most prescribed antipsychotic drug in children, on locomotor responses to the dopamine D1/D2 receptor agonist, apomorphine, and the D2/D3 receptor agonist, quinpirole. Female and male Long-Evans rats received daily subcutaneous injections of risperidone (1.0 and 3.0 mg/kg) or vehicle from postnatal day 14-42. Locomotor responses to one of three doses (0.03, 0.1, and 0.3 mg/kg) of apomorphine or quinpirole were tested once a week for four weeks beginning on postnatal day 76 and 147 for each respective drug. The locomotor activity elicited by the two lower doses of apomorphine was significantly greater in adult rats, especially females, administered risperidone early in life. Adult rats administered risperidone early in life also showed more locomotor activity after the low dose of quinpirole. Overall, female rats were more sensitive to the locomotor effects of each agonist. In a separate group of rats administered risperidone early in life, autoradiography of forebrain D2 receptors at postnatal day 62 revealed a modest increase in D2 receptor density in the medial caudate. These results provide evidence that early-life risperidone administration can produce long-lasting changes in dopamine receptor function and density.

Neonatal Cannabidiol Exposure Impairs Spatial Memory and Disrupts Neuronal Dendritic Morphology in Young Adult Rats

Introduction: Early life is a sensitive period for brain development. Perinatal exposure to cannabis is increasingly linked to disruption of neurodevelopment; however, research on the effects of cannabidiol (CBD) on the developing brain is scarce. In this study, we aim to study the developmental effects of neonatal CBD exposure on behavior and dendritic architecture in young adult rats. Materials and Methods: Male and female neonatal Sprague Dawley rats were treated with CBD (50 mg/kg) intraperitoneally on postnatal day (PND) 1, 3, and 5 and evaluated for behavioral and neuronal morphological changes during early adulthood. Rats were subjected to a series of behavioral tasks to evaluate long-term effects of neonatal CBD exposure, including the Barnes maze, open field, and elevated plus maze paradigms to assess spatial memory and anxiety-like behavior. Following behavioral evaluation, animals were sacrificed, and neuronal morphology of the cortex and hippocampus was assessed using Golgi-Cox (GC) staining. Results: Rats treated with CBD displayed a sexually dimorphic response in spatial memory, with CBD-treated females developing a deficit but not males. CBD did not elicit alterations in anxiety-like behavior in either sex. Neonatal CBD caused an overall decrease in dendritic length and spine density (apical and basal) in cortical and hippocampal neurons in both sexes. Sholl analysis also revealed a decrease in dendritic intersections in the cortex and hippocampus, indicating reduced dendritic arborization. Conclusions: This study provides evidence that neonatal CBD exposure perturbs normal brain development and leads to lasting alterations in spatial memory and neuronal dendrite morphology in early adulthood, with sex-dependent sensitivity.

Coping with the experience of frustration throughout life: Sex- and age-specific effects of early life stress on the susceptibility to reward devaluation

Early life stress may lead to lifelong impairments in psychophysiological functions, including emotional and reward systems. Unpredicted decrease in reward magnitude generates a negative emotional state (frustration) that may be involved with susceptibility to psychiatric disorders. We evaluated, in adolescents and adult rats of both sexes, whether maternal separation (MS) alters the ability to cope with an unexpected reduction of reward later in life. Litters of Wistar rats were divided into controls (non handled - NH) or subjected to MS. Animals were trained to find sugary cereal pellets; later the amount was reduced. Increased latency to reach the reward-associated area indicates higher inability to regulate frustration. The dorsal hippocampus (dHC) and basolateral amygdala (BLA) were evaluated for protein levels of NMDA receptor subunits (GluN2A/GluN2B), synaptophysin, PSD95, SNAP-25 and CRF1. We found that adult MS males had greater vulnerability to reward reduction, together with decreased GluN2A and increased GluN2B immunocontent in the dHC. MS females and adolescents did not differ from controls. We concluded that MS enhances the response to frustration in adult males. The change in the ratio of GluN2A and GluN2B subunits in dHC could be related to a stronger, more difficult to update memory of the aversive experience.

Early psychosocial parent-infant interventions and parent-infant relationships after preterm birth-a scoping review

Objective

Early psychosocial interventions for preterm infants and their parents are diverse. This study aimed to structure the knowledge on psychosocial parent-infant interventions and to identify gaps in the intervention studies.

Methods

We included studies on early (during first year of life) psychosocial parent-infant interventions with parent-infant relationship outcomes after preterm birth (< 37 weeks). We excluded studies that did not focus on preterm infants, failed to indicate the studied intervention and outcomes, were not written in English, were not controlled or peer-reviewed studies, or did not provide essential information for eligibility. The search included studies published between January 2000 and March 2024 in PubMed and PsycINFO. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed in reporting. Psychosocial parent-infant intervention studies were classified adapting the International Classification of Health Interventions (ICHI) and the Template for Intervention Description and Replication (TIDieR).

Results

The included 22 studies reported data from 18 different interventions with preterm infants (< 37 weeks). Studies excluded preterm infants with health risks (19/22, 86%), with very low gestational age and/or birth weight (7/22, 32%), and/or mothers with psychosocial risks (14/22, 64%). Of the 18 interventions, 12 (67%) were classified as counseling, 3 (17%) as emotional support, 2 (11%) as psychotherapeutic, and 1 (6%) as educational. The parent-child relationship was assessed using 30 different methods and varying time points up to 18 months of age. Most studies (17/22, 77%) reported positive changes in the parent-child relationship favoring the intervention group.

Conclusion

We identified four types of interventions to influence parenting behavior; the most used was counseling. All four intervention types showed positive effects on parent-infant relationships, although the preterm populations studied were selective, the effects were evaluated using different methods, and the follow-up periods were short. These findings indicate a need for studies with standardized methods, longer follow-up, and less-restricted preterm populations to develop guidelines for all families with preterm infants.

Do childhood experiences influence associations between posttraumatic stress disorder symptoms and positive autobiographical memories among military veteran students? An exploratory study

BACKGROUND

Evidence links posttraumatic stress disorder (PTSD) symptoms and features of positive autobiographical memories (accessibility, vividness, coherence, sharing, emotional intensity, distancing). There is a knowledge gap on how adverse childhood experiences (ACEs) and benevolent childhood experiences (BCEs) may influence these relationships.

OBJECTIVES

The current study explored whether the number ACEs or BCEs moderated associations between PTSD symptom severity and features of positive autobiographical memories.

DESIGN AND METHODS

The sample included 124 student military veterans who had experienced a trauma (Mage = 33.90; 77.4% male; 75.0% White).

RESULTS

Path analyses showed more PTSD symptom severity was significantly associated with less positive autobiographical memory vividness (β = -0.26, p = .019, R2 = 0.06). Further, the number of ACEs moderated the relationship between PTSD symptom severity and positive autobiographical memory accessibility (β = -0.25, p = .023, R2 = 0.10) and vividness (β = -0.20, p = .024, R2 = 0.10). Among individuals with more ACEs (1 SD above the mean) compared to those with fewer ACEs (1 SD below the mean), less accessibility and vividness of positive autobiographical memories was associated with greater PTSD symptom severity. The number of BCEs was not a significant moderator.

CONCLUSIONS

Positive memory-based interventions may be particularly useful to address PTSD symptoms among military veterans with a history of childhood adversity.

Postweaning stress affects behavior, brain and gut microbiota of adolescent mice in a sex-dependent manner

Aggression is an instinctive behavior that has been reported to be influenced by early-life stress. However, the potential effects of acute stress during the postweaning period, a key stage for brain development, on defensive aggression and the associated mechanism remain poorly understood. In the present study, aggressive behaviors were evaluated in adolescent mice exposed to postweaning stress. Serum corticosterone and testosterone levels, neural dendritic spine density, and gut microbiota composition were determined to identify the underlying mechanism. Behavioral analysis showed that postweaning stress reduced locomotor activity in mice and decreased defensive aggression in male mice. ELISA results showed that postweaning stress reduced serum testosterone levels in female mice. Golgi staining analysis demonstrated that postweaning stress decreased neural dendritic spine density in the medial prefrontal cortex of male mice. 16S rRNA sequencing results indicated that postweaning stress altered the composition of the gut microbiota in male mice. Combined, these results suggested that postweaning stress alters defensive aggression in male mice, which may be due to changes in neuronal structure as well as gut microbiota composition. Our findings highlight the long-lasting and sex-dependent effects of early-life experience on behaviors.

The Yin and Yang of the oxytocin and stress systems: opposites, yet interdependent and intertwined determinants of lifelong health trajectories

During parturition and the immediate post-partum period there are two opposite, yet interdependent and intertwined systems that are highly active and play a role in determining lifelong health and behaviour in both the mother and her infant: the stress and the anti-stress (oxytocin) system. Before attempting to understand how the environment around birth determines long-term health trajectories, it is essential to understand how these two systems operate and how they interact. Here, we discuss together the hormonal and neuronal arms of both the hypothalamic-pituitary-adrenal (HPA) axis and the oxytocinergic systems and how they interact. Although the HPA axis and glucocorticoid stress axis are well studied, the role of oxytocin as an extremely powerful anti-stress hormone deserves more attention. It is clear that these anti-stress effects depend on oxytocinergic nerves emanating from the supraoptic nucleus (SON) and paraventricular nucleus (PVN), and project to multiple sites at which the stress system is regulated. These, include projections to corticotropin releasing hormone (CRH) neurons within the PVN, to the anterior pituitary, to areas involved in sympathetic and parasympathetic nervous control, to NA neurons in the locus coeruleus (LC), and to CRH neurons in the amygdala. In the context of the interaction between the HPA axis and the oxytocin system birth is a particularly interesting period as, for both the mother and the infant, both systems are very strongly activated within the same narrow time window. Data suggest that the HPA axis and the oxytocin system appear to interact in this early-life period, with effects lasting many years. If mother-child skin-to-skin contact occurs almost immediately postpartum, the effects of the anti-stress (oxytocin) system become more prominent, moderating lifelong health trajectories. There is clear evidence that HPA axis activity during this time is dependent on the balance between the HPA axis and the oxytocin system, the latter being reinforced by specific somatosensory inputs, and this has long-term consequences for stress reactivity.

Measuring interpersonal trauma: Development and validation of the German version of the victimization experience schedule (VES)

OBJECTIVE

Interpersonal victimization experiences (VEs) significantly affect mental and physical health, particularly in disorders associated with life-time adversities, like fibromyalgia syndrome (FMS) and major depressive disorder (MDD). However, assessing VEs comprehensively remains challenging due to limited tools that encompass sub-traumatic events, such as bullying or discrimination, and contextual dimensions. We aimed to address this gap by validating the Victimization Experience Schedule (VES) in German, examining its reliability, and assessing VEs in clinical populations with FMS and MDD.

METHODS

We investigated the relationship between VEs and clinical symptoms in individuals with FMS, MDD and healthy controls (N = 105) in a case-control study. We also analyzed correlations between different types of VEs and categories of early childhood abuse and posttraumatic-stress-disorder instruments. Additionally, we validated our findings in an independent sample of individuals with FMS (N = 97) from a clinical study.

RESULTS

We observed excellent inter-rater reliability (Kw = 0.90-0.99), and VEs assessed using the VES were in alignment with subcategories of early childhood abuse. The prevalence of VEs extended beyond the categories covered by traditional survey instruments and was higher in individuals with MDD (4.0 ± 2.6) and FMS (5.9 ± 3.1) compared to controls (1.5 ± 1.7). We consistently identified a significant association between the number of VEs, the associated subjective distress, and clinical scores. Furthermore, distinct correlation patterns between VEs and clinical outcomes emerged across different cohorts.

CONCLUSION

Our study emphasizes the VES's value in understanding VEs within MDD and FMS. These experiences span from traumatic to sub-traumatic and correlate with posttraumatic-stress and clinical symptoms, underscoring the VES's importance as an assessment tool.

Relationship Between Neighborhood Poverty and Externalizing Symptoms in Children: Mediation and Moderation by Environmental Factors and Brain Structure

Children living in poverty exhibit worse mental health outcomes, and various environmental and neurological risk factors may contribute to or mitigate this relationship. However, previous research has not examined the interplay of neighborhood SES, mental health, and relevant mechanisms. We examined the extent to which neighborhood poverty uniquely contributes to children's internalizing/externalizing disorder symptoms, as well as identified whether brain measures, toxin levels, and neighborhood threat mediated this relationship and whether socioemotional support moderated it. Data were collected from 8623 9-10 year olds as part of the Adolescent Brain Cognitive Development study. Using a secondary data analysis, we found that neighborhood poverty was positively associated with externalizing symptoms and mediated by reduced intracranial volume and parents/children reporting feeling less safe. Parental support (i.e., Parental Monitoring Survey) attenuated this link, but only for children lower in poverty. Consideration of these risk factors for psychopathology could improve the outcome of holistic interventions.

Preterm infant mental health in the neonatal intensive care unit: A review of research on NICU parent-infant interactions and maternal sensitivity

Caregiving relationships in the postnatal period are critical to an infant's development. Preterm infants and their parents face unique challenges in this regard, with infants experiencing separation from parents, uncomfortable procedures, and increased biologic vulnerability, and parents facing difficulties assuming caregiver roles and increased risk for psychological distress. To better understand the NICU parent-infant relationship, we conducted a review of the literature and identified 52 studies comparing observed maternal, infant, and dyadic interaction behavior in preterm dyads with full-term dyads. Eighteen of 40 studies on maternal behavior found less favorable behavior, including decreased sensitivity and more intrusiveness in mothers of preterm infants, seven studies found the opposite, four studies found mixed results, and 11 studies found no differences. Seventeen of 25 studies on infant behavior found less responsiveness in preterm infants, two studies found the opposite, and the remainder found no difference. Eighteen out of 14 studies on dyad-specific behavior reported less synchrony in preterm dyads and the remainder found no differences. We identify confounding factors that may explain variations in results, present an approach to interpret existing data by framing differences in maternal behavior as potentially adaptive in the context of prematurity, and suggest future areas for exploration.

Neurodevelopmental, Mental Health, and Parenting Issues in Preterm Infants

The World Health Organization in its recommendations for the care of preterm infants has drawn attention to the need to address issues related to family involvement and support, including education, counseling, discharge preparation, and peer support. A failure to address these issues may translate into poor outcomes that extend across the lifespan. In this paper, we review the often far-reaching impact of preterm birth on the health and wellbeing of the parents and highlight the ways in which psychological stress may have a negative long-term impact on the parent-child interaction, attachment, and the styles of parenting. This paper addresses the following topics: (1) neurodevelopmental outcomes in preterm infants, including cognitive, sensory, and motor difficulties, (2) long-term mental health issues in premature infants that include elevated rates of anxiety and depressive disorders, autism, and somatization, which may affect social relationships and quality of life, (3) adverse mental health outcomes for parents that include elevated rates of depression, anxiety, and symptoms of post-traumatic stress, as well as increased rates of substance abuse, and relationship strain, (4) negative impacts on the parent-infant relationship, potentially mediated by maternal sensitivity, parent child-interactions, and attachment, and (5) impact on the parenting behaviors, including patterns of overprotective parenting, and development of Vulnerable Child Syndrome. Greater awareness of these issues has led to the development of programs in neonatal mental health and developmental care with some data suggesting benefits in terms of shorter lengths of stay and decreased health care costs.

Prenatal stress aggravates age-dependent cognitive decline, insulin signaling dysfunction, and the pro-inflammatory response in the APPNL-F/NL-F mouse model of Alzheimer's disease

Accumulating evidence indicates that early adverse life experiences may be involved in the pathogenesis of Alzheimer's disease (AD). Prenatal stress (PS) can affect brain maturation and neuroimmune and metabolic interactions, leading to age-dependent cognitive deficits in offspring. However, a multi-faceted cause-and-effect impact of PS on the development of cognitive deficits in the process of physiological ageing and in the APP^NL-F/NL-F mouse model of Alzheimer's disease has not yet been evaluated. We have identified age-dependent cognitive learning and memory deficits using male C57BL/6 J (wild type, WT) and the knock-in APP^NL-F/NL-F (KI) aged 12, 15, and 18 months. An increase in the Aβ42/Aβ40 ratio and mouse ApoE levels in the hippocampus and frontal cortex preceded the onset of cognitive deficits in the KI mice. Moreover, dysfunction in insulin signaling, including increased IRS-1 serine phosphorylation in both brain areas and the tyrosine phosphorylation deficit in the frontal cortex, suggested age-dependent insulin/IGF-1 resistance. Resistance was reflected by disturbances in mTOR or ERK1/2 kinase phosphorylation and excessive pro-inflammatory (TNF-α, IL-6, and IL-23) status in the KI mice. Importantly, our study has provided insights into the higher vulnerability to PS-induced exacerbation of age-dependent cognitive deficits and biochemical dysfunction in KI mice than in WT animals. We anticipate our study will lead to future investigation of a multi-faceted cause-and-effect relationship between stress during neurodevelopment and the onset of AD pathology, distinguishing it from changes in the course of dementia during normal ageing.

The effect of adverse childhood experiences on chronic pain and major depression in adulthood: a systematic review and meta-analysis

BACKGROUND

Adverse childhood experiences have been linked to increased multimorbidity, with physical and mental health consequences throughout life. Chronic pain is often associated with mood disorders, such as major depressive disorder (MDD); both have been linked to adverse childhood experiences. It is unclear how the effect of adverse childhood experiences on neural processing impacts on vulnerability to chronic pain, MDD, or both, and whether there are shared mechanisms. We aimed to assess evidence for central neural changes associated with adverse childhood experiences in subjects with chronic pain, MDD, or both using systematic review and meta-analysis.

METHODS

Electronic databases were systematically searched for neuroimaging studies of adverse childhood experiences, with chronic pain, MDD, or both. Two independent reviewers screened title, abstracts, and full text, and assessed quality. After extraction of neuroimaging data, activation likelihood estimate meta-analysis was performed to identify significant brain regions associated with these comorbidities.

RESULTS

Forty-nine of 2414 studies were eligible, of which 43 investigated adverse childhood experiences and MDD and six investigated adverse childhood experiences and chronic pain. None investigated adverse childhood experiences, chronic pain, and MDD together. Functional and structural brain abnormalities were identified in the superior frontal, lingual gyrus, hippocampus, insula, putamen, superior temporal, inferior temporal gyrus, and anterior cerebellum in patients with MDD exposed to adverse childhood experiences. In addition, brain function abnormalities were identified for patients with MDD or chronic pain and exposure to adverse childhood experiences in the cingulate gyrus, inferior parietal lobule, and precuneus in task-based functional MRI studies.

CONCLUSIONS

We found that adverse childhood experiences exposure can result in different functional and structural brain alterations in adults with MDD or chronic pain compared with those without adverse childhood experiences.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO CRD42021233989.

Neurophysiological and Psychosocial Mechanisms of Fibromyalgia: A Comprehensive Review and Call for An Integrative Model

Research into the neurobiological and psychosocial mechanisms involved in fibromyalgia has progressed remarkably in recent years. Despite this, current accounts of fibromyalgia fail to capture the complex, dynamic, and mutual crosstalk between neurophysiological and psychosocial domains. We conducted a comprehensive review of the existing literature in order to: a) synthesize current knowledge on fibromyalgia; b) explore and highlight multi-level links and pathways between different systems; and c) build bridges connecting disparate perspectives. An extensive panel of international experts in neurophysiological and psychosocial aspects of fibromyalgia discussed the collected evidence and progressively refined and conceptualized its interpretation. This work constitutes an essential step towards the development of a model capable of integrating the main factors implicated in fibromyalgia into a single, unified construct which appears indispensable to foster the understanding, assessment, and intervention for fibromyalgia.

Early-life stress affects Mongolian gerbil interactions with conspecific vocalizations in a sex-specific manner

During development, early-life stress (ELS) impairs cognition, learning, and emotional regulation, in part by disrupting neural circuitry in regions underlying these higher-order functions. In addition, our recent work indicates that ELS also alters simple sensory perception: ELS impaired auditory perception and neural encoding of short gaps in sounds, which are essential for vocal communication. The combination of higher-order and basic sensory disruption suggests that ELS is likely to affect both the perception and interpretation of communication signals. We tested this hypothesis by measuring behavioral responses to conspecific vocalizations (those emitted by other gerbils) in ELS and untreated Mongolian gerbils. Because stress effects often differ by sex, we separately examined females and males. To induce ELS, pups were intermittently maternally separated and restrained from post-natal days (P) 9-24, a time window when the auditory cortex is most sensitive to external disruption. We measured the approach responses of juvenile (P31-32) gerbils to two types of conspecific vocalizations: an alarm call, which is emitted to alert other gerbils of a potential threat, and the prosocial contact call, which is emitted near familiar gerbils, especially after separation. Control males, Control females, and ELS females approached a speaker emitting pre-recorded alarm calls, while ELS males avoided this source, suggesting that ELS affects the response to alarm calls in male gerbils. During playback of the pre-recorded contact call, Control females and ELS males avoided the sound source, while Control males neither approached nor avoided, and ELS females approached the sound. These differences cannot be accounted for by changes in locomotion or baseline arousal. However, ELS gerbils slept more during playback, suggesting that ELS may reduce arousal during vocalization playback. Further, male gerbils made more errors than females on a measure of working memory, but the sex difference of cognition in this context may stem from novelty aversion rather than impaired memory. These data indicate that ELS influences behavioral responses to ethologically relevant communication sounds in a sex-specific manner, and are among the first to demonstrate an altered response to auditory stimuli following ELS. Such changes may arise from differences in auditory perception, cognition, or a combination of factors, and suggest that ELS may affect auditory communication in human adolescents.

Protective effects of vanillic acid on autistic-like behaviors in a rat model of maternal separation stress: Behavioral, electrophysiological, molecular and histopathological alterations

Compounds derived from herbs exhibit a range of biological properties, including anti-inflammatory, antioxidant, and neuroprotective properties. However, the exact mechanism of action of these compounds in various neurological disorders is not fully discovered yet. Herein, the present work detected the effect of Vanillic acid (VA), a widely-used flavoring agent derived from vanillin, on autistic-like behaviors to assess the probable underlying mechanisms that mediate behavioral, electrophysiological, molecular, and histopathological alterations in the rat model of maternal separation (MS) stress. Maternal separated rats were treated with VA (25, 50, and 100 mg/kg interperitoneally for 14 days). In addition, anxiety-like, autistic-like behaviors, and learning and memory impairment were evaluated using various behavioral tests. Hippocampus samples were assessed histopathologically by H&E staining. Levels of malondialdehyde (MDA) and antioxidant capacity (by the FRAP method), as well as nitrite levels, were measured in brain tissue. Moreover, gene expression of inflammatory markers (IL-1β, TLR-4, TNF-α, and NLRP3) was evaluated in the hippocampus. Electrophysiological alterations were also estimated in the hippocampus by long-term potentiation (LTP) assessments. Results showed that VA reversed the negative effects of MS on behavior. VA increased the diameter and decreased the percentage of dark neurons in the CA3 area. Accordingly, VA decreased MDA and nitrite levels and increased the antioxidant capacity in brain samples and decreased the expression of all inflammatory genes. VA treated rats showed significant improvements in all LTP parameters. This study provided evidence suggesting a possible role for VA in preventing autism spectrum disorder (ASD) by regulating immune signaling.

Stress in adolescence as a first hit in stress-related disease development: Timing and context are crucial

The two-hit stress model predicts that exposure to stress at two different time-points in life may increase or decrease the risk of developing stress-related disorders later in life. Most studies based on the two-hit stress model have investigated early postnatal stress as the first hit with adult stress as the second hit. Adolescence, however, represents another highly sensitive developmental window during which exposure to stressful events may affect programming outcomes following exposure to stress in adulthood. Here, we discuss the programming effects of different types of stressors (social and nonsocial) occurring during adolescence (first hit) and how such stressors affect the responsiveness toward an additional stressor occurring during adulthood (second hit) in rodents. We then provide a comprehensive overview of the potential mechanisms underlying interindividual and sex differences in the resilience/susceptibility to developing stress-related disorders later in life when stress is experienced in two different life stages.

Early life adversity across different cell- types in the brain

Early life adversity (ELA)- which includes physical, psychological, emotional, and sexual abuse is one of the most common predictors to diverse psychopathologies later in adulthood. As ELA has a lasting impact on the brain at a developmental stage, recent findings from the field highlighted the specific contributions of different cell types to ELA and their association with long lasting consequences. In this review we will gather recent findings describing morphological, transcriptional and epigenetic alterations within neurons, glia and perineuronal nets and their associated cellular subpopulation. The findings reviewed and summarized here highlight important mechanisms underlying ELA and point to therapeutic approaches for ELA and related psychopathologies later in life.

Stress-induced plasticity of a CRH/GABA projection disrupts reward behaviors in mice

Disrupted operations of the reward circuit underlie major emotional disorders, including depression, which commonly arise following early life stress / adversity (ELA). However, how ELA enduringly impacts reward circuit functions remains unclear. We characterize a stress-sensitive projection connecting basolateral amygdala (BLA) and nucleus accumbens (NAc) that co-expresses GABA and the stress-reactive neuropeptide corticotropin-releasing hormone (CRH). We identify a crucial role for this projection in executing disrupted reward behaviors provoked by ELA: chemogenetic and optogenetic stimulation of the projection in control male mice suppresses several reward behaviors, recapitulating deficits resulting from ELA and demonstrating the pathway's contributions to normal reward behaviors. In adult ELA mice, inhibiting-but not stimulating-the projection, restores typical reward behaviors yet has little effect in controls, indicating ELA-induced maladaptive plasticity of this reward-circuit component. Thus, we discover a stress-sensitive, reward inhibiting BLA → NAc projection with unique molecular features, which may provide intervention targets for disabling mental illnesses.

Photobiomodulation attenuates oligodendrocyte dysfunction and prevents adverse neurological consequences in a rat model of early life adversity

Rationale: Adverse experiences in early life including abuse, trauma and neglect, have been linked to poor physical and mental health outcomes. Emerging evidence implies that those who experienced early life adversity (ELA) are more likely to develop cognitive dysfunction and depressive-like symptoms in adulthood. The molecular mechanisms responsible for the negative consequences of ELA, however, remain unclear. In the absence of effective management options, anticipatory guidance is the mainstay of ELA prevention. Furthermore, there is no available treatment that prevents or alleviates the neurologic sequelae of ELA, especially traumatic stress. Hence, the present study aims to investigate the mechanisms for these associations and evaluate whether photobiomodulation (PBM), a non-invasive therapeutic procedure, can prevent the negative cognitive and behavioral manifestations of ELA in later life. Methods: ELA was induced by repeated inescapable electric foot shock of rats from postnatal day 21 to 26. On the day immediately following the last foot shock, 2-min daily PBM treatment was applied transcranially for 7 consecutive days. Cognitive dysfunction and depression-like behaviors were measured by a battery of behavioral tests in adulthood. Subsequently, oligodendrocyte progenitor cells (OPCs) differentiation, the proliferation and apoptosis of oligodendrocyte lineage cells (OLs), mature oligodendrocyte, myelinating oligodendrocyte, the level of oxidative damage, reactive oxygen species (ROS) and total antioxidant capacity were measured and analyzed using immunofluorescence staining, capillary-based immunoassay (ProteinSimple®) and antioxidant assay kit. Results: The rats exposed to ELA exhibited obvious oligodendrocyte dysfunction, including a reduction in OPCs differentiation, diminished generation and survival of OLs, decreased OLs, and decreased matured oligodendrocyte. Furthermore, a deficit in myelinating oligodendrocytes was observed, in conjunction with an imbalance in redox homeostasis and accumulated oxidative damage. These alternations were concomitant with cognitive dysfunction and depression-like behaviors. Importantly, we found that early PBM treatment largely prevented these pathologies and reversed the neurologic sequelae resulting from ELA. Conclusions: Collectively, these findings provide new insights into the mechanism by which ELA affects neurological outcomes. Moreover, our findings support that PBM may be a promising strategy to prevent ELA-induced neurologic sequelae that develops later in life.

Early Life Stress Enhances Cognitive Decline and Alters Synapse Function and Interneuron Numbers in Young Male APP/PS1 Mice

BACKGROUND

Exposure to stress early in life increases the susceptibility to Alzheimer's disease (AD) pathology in aged AD mouse models. So far, the underlying mechanisms have remained elusive.

OBJECTIVE

To investigate 1) effects of early life stress (ELS) on early functional signs that precede the advanced neuropathological changes, and 2) correlate synaptosomal protein content with cognition to identify neural correlates of AD.

METHODS

APPswe/PS1dE9 mice and littermates were subjected to ELS by housing dams and pups with limited bedding and nesting material from postnatal days 2-9. At 3 months of age, an age where no cognitive loss or amyloid-β (Aβ) pathology is typically reported in this model, we assessed hippocampal Aβ pathology, synaptic strength and synapse composition and interneuron populations. Moreover, cognitive flexibility was assessed and correlated with synaptosomal protein content.

RESULTS

While ELS did not affect Aβ pathology, it increased synaptic strength and decreased the number of calretinin+ interneurons in the hippocampal dentate gyrus. Both genotype and condition further affected the level of postsynaptic glutamatergic protein content. Finally, APP/PS1 mice were significantly impaired in cognitive flexibility at 3 months of age, and ELS exacerbated this impairment, but only at relatively high learning criteria.

CONCLUSIONS

ELS reduced cognitive flexibility in young APP/PS1 mice and altered markers for synapse and network function. These findings at an early disease stage provide novel insights in AD etiology and in how ELS could increase AD susceptibility.

Emotion regulation and the salience network: a hypothetical integrative model of fibromyalgia

Fibromyalgia is characterized by widespread pain, fatigue, sleep disturbances and other symptoms, and has a substantial socioeconomic impact. Current biomedical and psychosocial treatments are unsatisfactory for many patients, and treatment progress has been hindered by the lack of a clear understanding of the pathogenesis of fibromyalgia. We present here a model of fibromyalgia that integrates current psychosocial and neurophysiological observations. We propose that an imbalance in emotion regulation, reflected by an overactive 'threat' system and underactive 'soothing' system, might keep the 'salience network' (also known as the midcingulo-insular network) in continuous alert mode, and this hyperactivation, in conjunction with other mechanisms, contributes to fibromyalgia. This proposed integrative model, which we term the Fibromyalgia: Imbalance of Threat and Soothing Systems (FITSS) model, should be viewed as a working hypothesis with limited supporting evidence available. We hope, however, that this model will shed new light on existing psychosocial and biological observations, and inspire future research to address the many gaps in our knowledge about fibromyalgia, ultimately stimulating the development of novel therapeutic interventions.

Differential impact of two paradigms of early-life adversity on behavioural responses to social defeat in young adult rats and morphology of CA3 pyramidal neurons

Early life stress (ELS) is an important factor in programing the brain for future response to stress, and resilience or vulnerability to stress-induced emotional disorders. The hippocampal formation, with essential roles in both regulating the stress circuitry and emotionality, contributes to this adaptive programing. Here, we examined the effects of early handling (EH) and maternal deprivation (MD) as mild and intense postnatal stressors, respectively, on the behavioural responses to social defeat stress in young adulthood. We also evaluated the interaction of mild and intense ELS with later social defeat (SD) stress on the morphology and dendritic spine density of Golgi-cox-stained CA3 hippocampal neurons. SD stress in adult rats, as expected, increased anxiety and depressive-like behaviours in the open field, elevated plus-maze and forced swimming test. These effects were associated with reduction of dendritic spines and soma size of CA3 neurons. Both behavioural and structural alterations were significantly ameliorated in socially defeated rats that experienced early handling (EH-SD). Basal dendrites of CA3 neurons in EH-SD rats also showed longer dendrites and more intersections with Sholl circles in the distal portion, compared to both control and SD rats. On the other hand, in socially defeated rats with maternal deprivation experience (MD-SD) the stress-induced behavioural and structural alterations were generally intensified compared to SD rats. In MD-SD rats, apical dendrites of CA3 neurons demonstrated remarkable retraction; an effect that was not detected in SD rats. The reduction of dendritic spines density on the apical dendrites of CA3 neurons was also more pronounced in MD-SD rats compared to SD rats. Dendritic arbors and spines comprise the major neuronal substrate for the circuit connectivity, and cell region-specific alterations of dendrites and spines in CA3 neurons reveal plausible mechanisms that can underlie the impact of different ELSs on risk for affective disorders in response to social stress in adulthood.

Behavioral effects of environmental enrichment on male and female wistar rats with early life stress experiences

Exposure to adverse childhood experiences or early life stress experiences (ELSs) increase the risk of non-adaptive behaviors and psychopathology in adulthood. Environmental enrichment (EE) has been proposed to minimize these effects. The vast number of methodological variations in animal studies underscores the lack of systematicity in the studies and the need for a detailed understanding of how enrichment interacts with other variables. Here we evaluate the effects of environmental enrichment in male and female Wistar rats exposed to adverse early life experiences (prenatal, postnatal, and combined) on emotional (elevated plus maze), social (social interaction chamber), memory (Morris water maze) and flexibility tasks. Our results—collected from PND 51 to 64—confirmed: 1) the positive effect of environmental enrichment (PND 28–49) on anxiety-like behaviors in animals submitted to ELSs. These effects depended on type of experience and type of enrichment: foraging enrichment reduced anxiety-like behaviors in animals with prenatal and postnatal stress but increased them in animals without ELSs. This effect was sex-dependent: females showed lower anxiety compared to males. Our data also indicated that females exposed to prenatal and postnatal stress had lower anxious responses than males in the same conditions; 2) no differences were found for social interactions; 3) concerning memory, there was a significant interaction between the three factors: A significant interaction for males with prenatal stress was observed for foraging enrichment, while physical enrichment was positive for males with postnatal stress; d) regarding cognitive flexibility, a positive effect of EE was found in animals exposed to adverse ELSs: animals with combined stress and exposed to physical enrichment showed a higher index of cognitive flexibility than those not exposed to enrichment. Yet, within animals with no EE, those exposed to combined stress showed lower flexibility than those exposed to both prenatal stress and no stress. On the other hand, animals with prenatal stress and exposed to foraging-type enrichment showed lower cognitive flexibility than those with no EE. The prenatal stress-inducing conditions used here 5) did not induced fetal or maternal problems and 6) did not induced changes in the volume of the dentate gyrus of the hippocampus.

Early life adversity shapes neural circuit function during sensitive postnatal developmental periods

Early life adversity (ELA) is a major risk factor for mental illness, but the neurobiological mechanisms by which ELA increases the risk for future psychopathology are still poorly understood. Brain development is particularly malleable during prenatal and early postnatal life, when complex neural circuits are being formed and refined through an interplay of excitatory and inhibitory neural input, synaptogenesis, synaptic pruning, myelination, and neurogenesis. Adversity that influences these processes during sensitive periods of development can thus have long-lasting and pervasive effects on neural circuit maturation. In this review, we will discuss clinical and preclinical evidence for the impact of ELA on neural circuit formation with a focus on the early postnatal period, and how long-lasting impairments in these circuits can affect future behavior. We provide converging evidence from human and animal studies on how ELA alters the functional development of brain regions, neural circuits, and neurotransmitter systems that are crucial for cognition and affective behavior, including the hippocampus, the hypothalamus-pituitary-adrenal (HPA) axis, neural networks of fear responses and cognition, and the serotonin (5-HT) system. We also discuss how gene-by-environment (GxE) interactions can determine individual differences in susceptibility and resilience to ELA, as well as molecular pathways by which ELA regulates neural circuit development, for which we emphasize epigenetic mechanisms. Understanding the molecular and neurobiological mechanisms underlying ELA effects on brain function and psychopathology during early postnatal sensitive periods may have great potential to advance strategies to better treat or prevent psychiatric disorders that have their origin early in life.

Challenges in the use of animal models and perspectives for a translational view of stress and psychopathologies

The neurobiology and development of treatments for stress-related neuropsychiatric disorders rely heavily on animal models. However, the complexity of these disorders makes it difficult to model them entirely, so only specific features of human psychopathology are emulated and these models should be used with great caution. Importantly, the effects of stress depend on multiple factors, like duration, context of exposure, and individual variability. Here we present a review on pre-clinical studies of stress-related disorders, especially those developed to model posttraumatic stress disorder, major depression, and anxiety. Animal models provide relevant evidence of the underpinnings of these disorders, as long as face, construct, and predictive validities are fulfilled. The translational challenges faced by scholars include reductionism and anthropomorphic/anthropocentric interpretation of the results instead of a more naturalistic and evolutionary understanding of animal behavior that must be overcome to offer a meaningful model. Other limitations are low statistical power of analysis, poor evaluation of individual variability, sex differences, and possible conflicting effects of stressors depending on specific windows in the lifespan.

Effects of Early Life Adversity on Tooth Enamel Formation

In a systemic effort to survive environmental stress, organ systems fluctuate and adapt to overcome external pressures. The evolutionary drive back toward homeostasis makes it difficult to determine if an organism experienced a toxic exposure to stress, especially in early prenatal and neonatal periods of development. Previous studies indicate that primary human teeth may provide historical records of experiences related to stressors during that early time window. To assess the molecular effects of early life adversity on enamel formation, we used a limited bedding and nesting (LBN) mouse model of early life adversity (ELA) to assess changes in the enamel organ gene expression and enamel matrix mineralization. On average, postnatal day 12 (P12) ELA mice weighed significantly less than the controls. When adjusted for animal weight, ELA molar enamel volume was reduced as compared with the controls, and the relative mineral density of molar enamel was significantly increased. There were no obvious changes in enamel matrix crystal morphology or structure in ELA as compared with the control mouse enamel. RNAseq showed extracellular matrix organization to be the most significantly affected GO and reactome pathways, whereas butanote metabolism was the most significantly altered KEGG pathway. Transcripts expressing the enamel matrix proteins amelogenin (Amelx) and enamelin (Enam) were among the top 4 most differentially expressed genes. When evaluating molecular mechanisms for the changes in gene expression in ELA enamel organs, we found significantly increased expression of Dlx3, while transcripts for clock genes Per1 and Nrd1 were downregulated. These findings support the possibility that the developing enamel organ is sensitive to the pressures of early life adversity and produces molecular and structural biomarkers reflecting these challenges.

Glucocorticoid Receptor Overexpression in the Dorsal Hippocampus Attenuates Spatial Learning and Synaptic Plasticity Deficits Following Pediatric Traumatic Brain Injury

Traumatic brain injury (TBI) in children younger than 4 years old leads to long-term deficits in cognitive and learning abilities that can persist or even worsen as children age into adolescence. In this study, the role of glucocorticoid receptor (GR) function in the dorsal hippocampus (DH) in hippocampal-dependent cognitive function and synaptic plasticity were assessed following injury to the 11-day-old rat. Brain injury produced significant impairments in spatial learning and memory in the Morris water maze in male and female rats at 1-month post-injury (adolescence) which was accompanied by impairments in induction and maintenance of long-term potentiation (LTP) in the CA1 region of the DH. Brain injury resulted in a significant decrease in the expression of the glucocorticoid-inducible gene, serum- and glucocorticoid-kinase 1 (sgk1), suggestive of an impairment in GR transcriptional activity within the hippocampus. Lentiviral transfection of the human GR (hGR) in the DH improved spatial learning and memory in the Morris water maze and attenuated LTP deficits following TBI. GR overexpression in the DH was also associated with a significant increase in the mRNA expression levels of sgk1, and the glutamate receptor subunits GluA1 and GluA2 within the hippocampus. Overall, these findings support an important role of dorsal hippocampal GR function in learning and memory deficits following pediatric TBI and suggest that these effects may be related to the regulation of glutamate receptor subunit expression in the DH.

Emotion Regulation as a Pathway Connecting Early Life Adversity and Inflammation in Adulthood: a Conceptual Framework

Chronic inflammation is implicated in a variety of diseases (e.g., cardiovascular disease and cancer). Much evidence suggests that early life adversity (ELA), such as maltreatment or neglect, can increase risk for inflammation in adulthood. ELA may program proinflammatory activity via its effects on brain areas involved in emotion regulation. Of multiple emotion regulation strategies, some are considered maladaptive (e.g., expressive suppression), while others are generally adaptive (e.g., cognitive reappraisal). We propose a conceptual framework for how emotion regulation tendencies may affect vulnerability or resilience to inflammation in adults who experienced adversity in childhood and/or adolescence. In support of this framework, we summarize evidence for the relationships between emotion dysregulation and higher inflammation (i.e., vulnerability), as well as between cognitive reappraisal and lower inflammation (i.e., resilience), in healthy adults with a history of ELA. Plausible neurobiological, physiological, psychosocial, and ELA-specific factors, as well as interventions, contributing to these associations are discussed. Strengths and limitations of the extant research, in addition to ideas for future directions, are presented.

Prepulse inhibition can predict the motivational effects of cocaine in female mice exposed to maternal separation

The prepulse inhibition (PPI) of the startle response can identify the rodents that are more sensitive to the effects of cocaine. Mice with a lower PPI presented a higher vulnerability to the effects of cocaine and a higher susceptibility to developing a substance use disorder (SUD). Maternal separation with early weaning (MSEW) is a relevant animal model to induce motivational alterations throughout life. Nevertheless, only a few studies on females exist, even though they are more vulnerable to stress- and cocaine-related problems. Hence, the aim of the present study was to evaluate the ability of PPI to identify females with a greater vulnerability to the long-term consequences of early stress on the motivational effects of cocaine. Female mice underwent MSEW and were classified according to their high or low PPI. They were then assessed in the cocaine-induced locomotor sensitization test, the conditioned place preference paradigm or the operant self-administration paradigm. Additionally, they were also evaluated in the passive avoidance task, the tail-suspension and the splash tests. The results revealed that the females with lower PPI presented higher consequences of MSEW on the effects of cocaine and showed an increase in anhedonia-like behaviours. Our findings support that a PPI deficit could represent a biomarker of vulnerability to the effects of cocaine induced by MSEW.

Sex Differences in Affective Dysfunction and Alterations in Parvalbumin in Rodent Models of Early Life Adversity

The early life environment markedly influences brain and behavioral development, with adverse experiences associated with increased risk of anxiety and depressive phenotypes, particularly in females. Indeed, early life adversity (ELA) in humans (i.e., caregiver deprivation, maltreatment) and rodents (i.e., maternal separation, resource scarcity) is associated with sex-specific emergence of anxious and depressive behaviors. Although these disorders show clear sex differences in humans, little attention has been paid toward evaluating sex as a biological variable in models of affective dysfunction; however, recent rodent work suggests sex-specific effects. Two widely used rodent models of ELA approximate caregiver deprivation (i.e., maternal separation) and resource scarcity (i.e., limited bedding). While these approaches model aspects of ELA experienced in humans, they span different portions of the pre-weaning developmental period and may therefore differentially contribute to underlying mechanistic risk. This is borne out in the literature, where evidence suggests differences in trajectories of behavior depending on the type of ELA and/or sex; however, the neural underpinning of these differences is not well understood. Because anxiety and depression are thought to involve dysregulation in the balance of excitatory and inhibitory signaling in ELA-vulnerable brain regions (e.g., prefrontal cortex, amygdala, hippocampus), outcomes are likely driven by alterations in local and/or circuit-specific inhibitory activity. The most abundant GABAergic subtypes in the brain, accounting for approximately 40% of inhibitory neurons, contain the calcium-binding protein Parvalbumin (PV). As PV-expressing neurons have perisomatic and proximal dendritic targets on pyramidal neurons, they are well-positioned to regulate excitatory/inhibitory balance. Recent evidence suggests that PV outcomes following ELA are sex, age, and region-specific and may be influenced by the type and timing of ELA. Here, we suggest the possibility of a combined role of PV and sex hormones driving differences in behavioral outcomes associated with affective dysfunction following ELA. This review evaluates the literature across models of ELA to characterize neural (PV) and behavioral (anxiety- and depressive-like) outcomes as a function of sex and age. Additionally, we detail a putative mechanistic role of PV on ELA-related outcomes and discuss evidence suggesting hormone influences on PV expression/function which may help to explain sex differences in ELA outcomes.

Impaired social cognition caused by perinatal protein malnutrition evokes neurodevelopmental disorder symptoms and is intergenerationally transmitted

Nutritional inadequacy before birth and during postnatal life can seriously interfere with brain development and lead to persistent deficits in learning and behavior. In this work, we asked if protein malnutrition affects domains of social cognition and if these phenotypes can be transmitted to the next generation. Female mice were fed with a normal or hypoproteic diet during pregnancy and lactation. After weaning, offspring were fed with a standard chow. Social interaction, social recognition memory, and dominance were evaluated in both sexes of F1 offspring and in the subsequent F2 generation. Glucose metabolism in the whole brain was analyzed through preclinical positron emission tomography. Genome-wide transcriptional analysis was performed in the medial prefrontal cortex followed by gene-ontology enrichment analysis. Compared with control animals, malnourished mice exhibited a deficit in social motivation and recognition memory and displayed a dominant phenotype. These altered behaviors, except for dominance, were transmitted to the next generation. Positron emission tomography analysis revealed lower glucose metabolism in the medial prefrontal cortex of F1 malnourished offspring. This brain region showed genome-wide transcriptional dysregulation, including 21 transcripts that overlapped with autism-associated genes. Our study cannot exclude that the lower maternal care provided by mothers exposed to a low-protein diet caused an additional impact on social cognition. Our results showed that maternal protein malnutrition dysregulates gene expression in the medial prefrontal cortex, promoting altered offspring behavior that was intergenerationally transmitted. These results support the hypothesis that early nutritional deficiency represents a risk factor for the emergence of symptoms associated with neurodevelopmental disorders.

Children with developmental dyslexia show elevated parasympathetic nervous system activity at rest and greater cardiac deceleration during an empathy task

Reading difficulties are the hallmark feature of dyslexia, but less is known about other areas of functioning. Previously, we found children with dyslexia exhibited heightened emotional reactivity, which correlated with better social skills. Whether emotional differences in dyslexia extend to the parasympathetic nervous system-an autonomic branch critical for attention, social engagement, and empathy-is unknown. Here, we measured autonomic nervous system activity in 24 children with dyslexia and 24 children without dyslexia, aged 7 - 12, at rest and during a film-based empathy task. At rest, children with dyslexia had higher respiratory sinus arrhythmia (RSA) than those without dyslexia. Cardiac deceleration during the empathy task was greater in dyslexia and correlated with higher resting RSA across the sample. Children with dyslexia produced more facial expressions of concentration during film-viewing, suggesting greater engagement. These results suggest elevated resting parasympathetic activity and accentuated autonomic and behavioral responding to others' emotions in dyslexia.

Downregulation of kainate receptors regulating GABAergic transmission in amygdala after early life stress is associated with anxiety-like behavior in rodents

Early life stress (ELS) is a well-characterized risk factor for mood and anxiety disorders. GABAergic microcircuits in the amygdala are critically implicated in anxiety; however, whether their function is altered after ELS is not known. Here we identify a novel mechanism by which kainate receptors (KARs) modulate feedforward inhibition in the lateral amygdala (LA) and show that this mechanism is downregulated after ELS induced by maternal separation (MS). Specifically, we show that in control rats but not after MS, endogenous activity of GluK1 subunit containing KARs disinhibit LA principal neurons during activation of cortical afferents. GluK1 antagonism attenuated excitability of parvalbumin (PV)-expressing interneurons, resulting in loss of PV-dependent inhibitory control and an increase in firing of somatostatin-expressing interneurons. Inactivation of Grik1 expression locally in the adult amygdala reduced ongoing GABAergic transmission and was sufficient to produce a mild anxiety-like behavioral phenotype. Interestingly, MS and GluK1-dependent phenotypes showed similar gender specificity, being detectable in male but not female rodents. Our data identify a novel KAR-dependent mechanism for cell-type and projection-specific functional modulation of the LA GABAergic microcircuit and suggest that the loss of GluK1 KAR function contributes to anxiogenesis after ELS.

Early life exposure to poly I:C impairs striatal DA-D2 receptor binding, myelination and associated behavioural abilities in rats

Early-life viral infections critically influence the brain development and have been variously reported to cause neuropsychiatric diseases such as Schizophrenia, Parkinson's diseases, demyelinating diseases, etc. To investigate the alterations in the dopaminergic system, myelination and associated behavioral impairments following neonatal viral infection, the viral immune activation model was created by an intraperitoneal injection of Poly I:C (5 mg/kg bw/ip) to neonatal rat pups on PND-7. The DA-D2 receptor binding was assessed in corpus striatum by using ³H-Spiperone at 3, 6 and 12 weeks of age. MOG immunolabelling was performed to check myelination stature and myelin integrity, while corpus callosum calibre was assessed by Luxol fast blue staining. Relative behavioral tasks i.e., motor activity, motor coordination and neuromuscular strength were assessed by open field, rotarod and grip strength meter respectively at 3, 6 and 12 weeks of age. Following Poly I:C exposure, a significant decrease in DA-D2 receptor binding, reduction in corpus callosum calibre and MOG immunolabelling indicating demyelination and a significant decrease in locomotor activity, neuromuscular strength and motor coordination signify motor deficits and hypokinetic influence of early life viral infection. Thus, the findings suggest that early life poly I:C exposure may cause demyelination and motor deficits by decreasing DA-D2 receptor binding affinity.

Traumatic Injury to the Developing Brain: Emerging Relationship to Early Life Stress

Despite the high incidence of brain injuries in children, we have yet to fully understand the unique vulnerability of a young brain to an injury and key determinants of long-term recovery. Here we consider how early life stress may influence recovery after an early age brain injury. Studies of early life stress alone reveal persistent structural and functional impairments at adulthood. We consider the interacting pathologies imposed by early life stress and subsequent brain injuries during early brain development as well as at adulthood. This review outlines how early life stress primes the immune cells of the brain and periphery to elicit a heightened response to injury. While the focus of this review is on early age traumatic brain injuries, there is also a consideration of preclinical models of neonatal hypoxia and stroke, as each further speaks to the vulnerability of the brain and reinforces those characteristics that are common across each of these injuries. Lastly, we identify a common mechanistic trend; namely, early life stress worsens outcomes independent of its temporal proximity to a brain injury.

Unbiased Screening Identifies Functional Differences in NK Cells After Early Life Psychosocial Stress

Early Life Adversity (ELA) is closely associated with the risk for developing diseases later in life, such as autoimmune diseases, type-2 diabetes and cardiovascular diseases. In humans, early parental separation, physical and sexual abuse or low social-economic status during childhood are known to have great impact on brain development, in the hormonal system and immune responses. Maternal deprivation (MD) is the closest animal model available to the human situation. This paradigm induces long lasting behavioral effects, causes changes in the HPA axis and affects the immune system. However, the mechanisms underlying changes in the immune response after ELA are still not fully understood. In this study we investigated how ELA changes the immune system, through an unbiased analysis, viSNE, and addressed specially the NK immune cell population and its functionality. We have demonstrated that maternal separation, in both humans and rats, significantly affects the sensitivity of the immune system in adulthood. Particularly, NK cells’ profile and response to target cell lines are significantly changed after ELA. These immune cells in rats are not only less cytotoxic towards YAC-1 cells, but also show a clear increase in the expression of maturation markers after 3h of maternal separation. Similarly, individuals who suffered from ELA display significant changes in the cytotoxic profile of NK cells together with decreased degranulation capacity. These results suggest that one of the key mechanisms by which the immune system becomes impaired after ELA might be due to a shift on the senescent state of the cells, specifically NK cells. Elucidation of such a mechanism highlights the importance of ELA prevention and how NK targeted immunotherapy might help attenuating ELA consequences.

The Paraventricular Thalamus: A Potential Sensor and Integrator of Emotionally Salient Early-Life Experiences

Early-life experiences influence a broad spectrum of behaviors throughout the lifespan that contribute to resilience or vulnerability to mental health disorders. Yet, how emotionally salient experiences early in life are encoded, stored, and processed and the mechanisms by which they influence future behaviors remain poorly understood. The paraventricular nucleus of the thalamus (PVT) is a key structure in modulating positive and negative experiences and behaviors in adults. However, little is known of the PVT's role in encoding and integrating emotionally salient experiences that occur during neonatal, infancy, and childhood periods. In this review, we (1) describe the functions and connections of the PVT and its regulation of behavior, (2) introduce novel technical approaches to elucidating the role of the PVT in mediating enduring changes in adult behaviors resulting from early-life experiences, and (3) conclude that PVT neurons of neonatal rodents are engaged by both positive and negative emotionally salient experiences, and their activation may enduringly govern future behavior-modulating PVT activity during emotionally salient contexts.

Salivary cytokine cluster moderates the association between caregivers perceived stress and emotional functioning in youth

Some individuals exposed to early life stress show evidence of enhanced systemic inflammation and are at greater risk for psychopathology. In the current study, caregivers and their offspring (0-17 years) were recruited at a pediatric clinic visit at the University of California, San Francisco (UCSF). Mothers and seven-year-old children from the Growing Up inSingaporeTowards healthy Outcomes (GUSTO) prospective birth cohort were used as a replication cohort. Caregivers perceived stress was measured to determine potential intergenerational effects on the children's functioning and inflammation levels. Children's emotional functioning in the UCSF cohort was evaluated using the Pediatric Quality of Life (PedsQL) inventory. Child emotional and behavioral functioning was measured using the Child Behavior Checklist (CBCL) in GUSTO. Saliva was collected from the children and salivary levels of IL-6, IL-1β, IL-8 and TNF-α were measured using an electrochemiluminescent cytokine multiplex panel. Child IL-6, IL-1β, IL-8 cytokine levels were clustered into low, average, and high cytokine cluster groups using hierarchical cluster analysis. We did not find that salivary cytokine clusters were significantly associated with children's emotional or behavioral function. However, cytokine clusters did significantly moderate the association between increased caregiver perceived stress and reduced child emotional functioning (UCSF cohort) and increased Attention-Deficit-Hyperactivity (ADH) problems (GUSTO cohort, uncorrected Cohen's F2 = 0.02). Using a cytokine clustering technique may be useful in identifying those children exposed to increased caregiver perceived stress that are at risk of emotional and attention deficit hyperactivity problems.

Promoting infant mental health in the neonatal intensive care unit (NICU): A review of nurturing factors and interventions for NICU infant-parent relationships

Premature and medically vulnerable infants experience early and sometimes prolonged separation from their parents, intrusive and unnatural environments, painful and distressing procedures, difficulties with physiological regulation, increased biological and neurological vulnerabilities, and grow up to have higher rates of neurocognitive and psychosocial difficulties. Parents of infants born prematurely or with medical vulnerabilities, in turn, experience significant distress and are a psychiatrically vulnerable population, with very high rates of depression, anxiety, and posttraumatic stress disorder. The combination of these factors cause significant challenges for some of these infants and parents in developing an early optimal relationship and connection. Given the critical importance of early relationships with main caregivers for infant mental health and long-term developmental outcomes, we review various targets of intervention to promote healthy infant and parent mental health and bonding thereby facilitating an optimal infant-parent relationship in the NICU population.

SAHA Improves Depressive Symptoms, Cognitive Impairment and Oxidative Stress: Rise of a New Antidepressant Class

Depression is a disabling psychiatric disorder affecting millions of people all around the world. Under current therapeutic choices, a portion of patients are not responsive, have relapses, or experience cognitive side effects. Hence, the present study aimed to find other antidepressant compounds lacking the mentioned deficiency. Since epigenetic regulations have attracted more attention in etiology of depression, histone deacetylase (HDAC) inhibitors have gained more importance due to their possible antidepressant activity. We selected a promising member of HDAC inhibitors named suberanilohydroxamic acid (SAHA) to evaluate its antidepressant properties. Early life stress disarrays many neurodevelopmental factors and consequently, leads to the destruction of hippocampus and prefrontal cortex synapses as areas highly related to emotion and memory so that any destruction on them can cause lasting impairments. For that reason, we used maternal separation (MS) paradigm to investigate depression in male mice. To compare the efficacy of SAHA with current treatment options, we also treated a group of MS mice with fluoxetine (FLX) as first-line pharmacological drugs of depression. The results demonstrated that depressive-like behavior, cognitive function and inflammatory response of MS mice were attenuated with SAHA. Our data showed that, besides anti-depressant and cognition-boosting effects similar to FLX, SAHA counteracted inflammatory response caused by depression and reversed the coenzyme Q₁₀ (CoQ₁₀) level in hippocampus. SAHA's effect on alleviating depressive behavior was accompanied with memory enhancement and hippocampus biochemical tests. These findings may propose SAHA as another therapeutic option for depressive symptoms, especially with comorbid cognitive impairment.

The Developmental Origins of Opioid Use Disorder and Its Comorbidities

Opioid use disorder (OUD) rarely presents as a unitary psychiatric condition, and the comorbid symptoms likely depend upon the diverse risk factors and mechanisms by which OUD can arise. These factors are heterogeneous and include genetic predisposition, exposure to prescription opioids, and environmental risks. Crucially, one key environmental risk factor for OUD is early life adversity (ELA). OUD and other substance use disorders are widely considered to derive in part from abnormal reward circuit function, which is likely also implicated in comorbid mental illnesses such as depression, bipolar disorder, and schizophrenia. ELA may disrupt reward circuit development and function in a manner predisposing to these disorders. Here, we describe new findings addressing the effects of ELA on reward circuitry that lead to OUD and comorbid disorders, potentially via shared neural mechanisms. We discuss some of these OUD-related problems in both humans and animals. We also highlight the increasingly apparent, crucial contribution of biological sex in mediating the range of ELA-induced disruptions of reward circuitry which may confer risk for the development of OUD and comorbid neuropsychiatric disorders.

Social Defeat Stress During Early Adolescence Confers Resilience Against a Single Episode of Prolonged Stress in Adult Rats

Early-life adverse experiences (first hit) lead to coping strategies that may confer resilience or vulnerability to later experienced stressful events (second hit) and the subsequent development of stress-related psychopathologies. Here, we investigated whether exposure to two stressors at different stages in life has long-term effects on emotional and cognitive capabilities, and whether the interaction between the two stressors influences stress resilience. Male rats were subjected to social defeat stress (SDS, first hit) in adolescence and to a single episode of prolonged stress (SPS, second hit) in adulthood. Behavioral outcomes, hippocampal expression of brain-derived neurotrophic factor, and plasma corticosterone levels were tested in adulthood. Rats exposed to both stressors exhibited resilience against the development of stress-induced alterations in emotional behaviors and spatial memory, but vulnerability to cued fear memory dysfunction. Rats subjected to both stressors demonstrated resilience against the SDS-induced alterations in hippocampal brain-derived neurotrophic factor expression and plasma corticosterone levels. SPS alone altered locomotion and spatial memory retention; these effects were absent in SDS-exposed rats later exposed to SPS. Our findings reveal that exposure to social stress during early adolescence influences the ability to cope with a second challenge experienced later in life.

An Evolutionary Perspective of Dyslexia, Stress, and Brain Network Homeostasis

Evolution fuels interindividual variability in neuroplasticity, reflected in brain anatomy and functional connectivity of the expanding neocortical regions subserving reading ability. Such variability is orchestrated by an evolutionarily conserved, competitive balance between epigenetic, stress-induced, and cognitive-growth gene expression programs. An evolutionary developmental model of dyslexia, suggests that prenatal and childhood subclinical stress becomes a risk factor for dyslexia when physiological adaptations to stress promoting adaptive fitness, may attenuate neuroplasticity in the brain regions recruited for reading. Stress has the potential to blunt the cognitive-growth functions of the predominantly right hemisphere Ventral and Dorsal attention networks, which are primed with high entropic levels of synaptic plasticity, and are critical for acquiring beginning reading skills. The attentional networks, in collaboration with the stress-responsive Default Mode network, modulate the entrainment and processing of the low frequency auditory oscillations (1-8 Hz) and visuospatial orienting linked etiologically to dyslexia. Thus, dyslexia may result from positive, but costly adaptations to stress system dysregulation: protective measures that reset the stress/growth balance of processing to favor the Default Mode network, compromising development of the attentional networks. Such a normal-variability conceptualization of dyslexia is at odds with the frequent assumption that dyslexia results from a neurological abnormality. To put the normal-variability model in the broader perspective of the state of the field, a traditional evolutionary account of dyslexia is presented to stimulate discussion of the scientific merits of the two approaches.

Evaluation of the HPA Axis' Response to Pharmacological Challenges in Experimental and Clinical Early-Life Stress-Associated Depression

Early-life stress (ELS) is associated with a higher risk of psychopathologies in adulthood, such as depression, which may be related to persistent changes in the hypothalamic-pituitary-adrenal (HPA) axis. This study aimed to evaluate the effects of ELS on the functioning of the HPA axis in clinical and experimental situations. Clinically, patients with current depressive episodes, with and without ELS, and healthy controls, composed the sample. Subjects took a capsule containing placebo, fludrocortisone, prednisolone, dexamethasone or spironolactone followed by an assessment of plasma cortisol the morning after. Experimentally, male Wistar rats were submitted to ELS protocol based on variable, unpredictable stressors from postnatal day (PND)1 to PND21. On PND65 animals were behaviorally evaluated through the forced-swimming test (FST). At PND68, pharmacological challenges started, using mifepristone, dexamethasone, spironolactone, or fludrocortisone, and corticosterone levels were determined 3 h after injections. Cortisol response of the patients did not differ significantly from healthy subjects, regardless of their ELS history, and it was lower after fludrocortisone, prednisolone, and dexamethasone compared with placebo, indicating the suppression of plasma cortisol by all these treatments. Animals exposed to ELS presented altered phenotype as indicated by an increased immobility time in the FST when compared with control, but no significant long-lasting effects of ELS were observed on the HPA axis response. Limitations on the way the volunteers were sampled may have contributed to the lack of ELS effects on the HPA axis, pointing out the need for further research to understand these complex phenomena.

Long-Term Decreases in the Expression of Calcineurin and GABAA Receptors Induced by Early Maternal Separation Are Associated with Increased Anxiety-Like Behavior in Adult Male Rats

INTRODUCTION

Early life stress is a well-described risk factor of anxiety disorders in adulthood. Dysfunction in GABA/glutamate receptors and their functional regulator, calcineurin, is linked to anxiety disorders. Here, we investigated the effect of early life stress, such as repeated maternal separation (MS; 3 h per day from postnatal day [P] 2 to 11), on changes in the expression of calcineurin as well as the ionotropic glutamatergic and GABAergic receptors including α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-D-aspartate (NMDA) and GABAA receptors in the hippocampus and prefrontal cortex (PFC) of adolescent (P35) and adult (P62) male Wistar rats and their correlations with anxiety-like behavior in adulthood.

METHODS

The protein levels were assessed by Western blot analysis. Anxiety-like behavior was measured in the elevated plus maze (EPM) and open field (OF) tests.

RESULTS

MS induced a regional transient decrease of glutamate receptors expression at P35, with decreased NMDA and AMPA receptor levels, respectively, in the hippocampus and PFC, suggesting a possible decrease in excitatory synaptic strength. In contrast to glutamate receptors, MS had long-lasting influence on GABAA receptor and calcineurin levels, with reduced expression of GABAA receptor and calcineurin in both brain regions at P35 that continued into adulthood. These results were accompanied by increased anxiety behavior in adulthood, shown by lower percentage of number of total entries and time spent in the open arms of the EPM, and by lower time spent and number of entries in the OF central area.

CONCLUSIONS

Together, our study suggests that GABAA receptors via calcineurin-dependent signaling pathways may play an important role in the expression of stress-induced anxiety-like behavior.