Early-life and pubertal stress differentially modulate grey matter development in human adolescents

Functional Alterations and Cerebral Variations in Humans Exposed to Early Life Stress

Early life stress can be caused by acute or chronic exposure to childhood events, such as emotional, physical, sexual abuse, and neglect. Early stress is associated with subsequent alterations in physical and mental health, which can extend into adolescence, adulthood, and even old age. The effects of early stress exposure include alterations in cognitive, neuropsychological, and behavioral functions, and can even lead to the development of psychiatric disorders and changes in brain anatomy. The present manuscript provides a review of the main findings on these effects reported in the scientific literature in recent decades. Early life stress is associated with the presence of psychiatric disorders, mainly mood disorders such as depression and risk of suicide, as well as with the presence of post-traumatic stress disorder. At the neuropsychological level, the involvement of different mental processes such as executive functions, abstract reasoning, certain memory modalities, and poor school-skill performance has been reported. In addition, we identified reports of alterations of different subdomains of each of these processes. Regarding neuroanatomical effects, the involvement of cortical regions, subcortical nuclei, and the subcortical white matter has been documented. Among the telencephalic regions most affected and studied are the prefrontal cortex, the hippocampus, the amygdala, and the anterior cingulate cortex. Understanding the impact of early life stress on postnatal brain development is very important for the orientation of therapeutic intervention programs and could help in the formulation and implementation of preventive measures as well as in the reorientation of research targets.

Pubertal development mediates the association between family environment and brain structure and function in childhood

Psychosocial acceleration theory suggests that pubertal maturation is accelerated in response to adversity. In addition, suboptimal caregiving accelerates development of the amygdala–medial prefrontal cortex circuit. These findings may be related. Here, we assess whether associations between family environment and measures of the amygdala–medial prefrontal cortex circuit are mediated by pubertal development in more than 2000 9- and 10-year-old children from the Adolescent Brain Cognitive Development Study (http://dx.doi.org/10.15154/1412097). Using structural equation modeling, demographic, child-reported, and parent-reported data on family dynamics were compiled into a higher level family environment latent variable. Magnetic resonance imaging preprocessing and compilations were performed by the Adolescent Brain Cognitive Development Study's data analysis core. Anterior cingulate cortex (ACC) thickness, area, white matter fractional anisotropy, amygdala volume, and cingulo-opercular network–amygdala resting-state functional connectivity were assessed. For ACC cortical thickness and ACC fractional anisotropy, significant indirect effects indicated that a stressful family environment relates to more advanced pubertal stage and more mature brain structure. For cingulo-opercular network–amygdala functional connectivity, results indicated a trend in the expected direction. For ACC area, evidence for quadratic mediation by pubertal stage was found. Sex-stratified analyses suggest stronger results for girls. Despite small effect sizes, structural measures of circuits important for emotional behavior are associated with family environment and show initial evidence of accelerated pubertal development.

The amygdala in adolescents with attention-deficit/hyperactivity disorder: Structural and functional correlates of delay aversion

OBJECTIVES

Recent magnetic resonance imaging (MRI) studies implicate structural alterations of amygdala, a brain region responsible for processing and experiencing negative emotions, in adolescents with attention-deficit/hyperactivity disorder (ADHD). Here we examined ADHD-related structural correlates of amygdala functional activity elicited during a functional MRI task designed to test behavioural and brain responses to the imposition of delay - an event known to both elicit amygdala hyperactivation and aversity in ADHD.

METHODS

Structural MRI scans from 28 right-handed male adolescents with combined type ADHD and 32 age-matched controls were analysed. Regional grey matter volumes of ADHD and control participants (P[FWE] < 0.05) were correlated with delay aversion self-ratings and neural activity in response to delay-related cues on the Escape Delay Incentive fMRI task.

RESULTS

ADHD was associated with significantly reduced volumes in bilateral amygdala, parahippocampal and temporal gyrus (P[FWE] < 0.05), greater basolateral amygdala activation to delay-related cues (P[FWE] < 0.05) and higher delay aversion self-ratings. Amygdala volume reductions were significantly correlated with, and statistically mediated the pathway from ADHD to, delay-cue-related amygdala hyperactivity (P < 0.01) and self-reported delay aversion (P < 0.01).

CONCLUSIONS

We provide the first evidence of the functional significance of reduced amygdala volumes in adolescents with ADHD by highlighting its relation to delay-induced brain activity that is linked to delay aversion.

Childhood emotional neglect and oxytocin receptor variants: Association with limbic brain volumes

Objectives: Childhood emotional neglect (EN) is a predictor for the development of affective disorders. Oxytocin (OXT) may mediate the interplay between EN and changes in stress biological systems, brain development, and mental health outcomes. We investigated, in a cross-sectional study, the associations between EN, (epi)genetic variation in the OXT receptor (OXTR) gene, and amygdalar and hippocampal volumes, two brain regions implicated in emotional processing.Methods: We recruited 63 Caucasian South African adults (35 women) with and without social anxiety disorder. Childhood EN was assessed using the Childhood Trauma Questionnaire. rs53576 and rs2254298 genotypes, as well as methylation status, was determined using DNA purified from whole blood. Bilateral amygdalar and hippocampal volumes were determined by structural magnetic resonance imaging. The relationships between these variables were investigated using linear regression.Results: The interaction of the rs2254298 A risk allele and EN was nominally associated with reduced left hippocampal volume. The rs2254298 A risk allele was independently associated with reduced bilateral amygdalar volumes. We found no association between EN, OXTR methylation and amygdalar or hippocampal volumes. The rs53576 GG risk genotype was, however, associated with decreased OXTR methylation.Conclusions: The rs2254298 A allele may increase susceptibility to the structural brain effects of EN.

Childhood abuse history and attention bias in adults

Attention biases toward unpleasant information are evident among children and adults with a history of abuse and have been identified as a potential pathway through which abused children develop psychopathology. Identifying whether a history of childhood abuse affects the time course of attention biases in adults is critical, as this may provide intervention targets. The present study examined the time course of attention bias during an emotion-word Stroop task using event-related potentials (ERPs) in a sample of adults with a range of child abuse histories using a categorical approach (comparing adults with or without a history of moderate-to-severe childhood abuse) and a dimensional approach (analyzing the range from no abuse to severe abuse in a continuous manner). Although behavioral performance did not vary as a function of abuse history, adults with a history of moderate-to-severe childhood abuse showed ERP evidence of early reduced processing of emotional stimuli (smaller N200) and later reduced processing of emotional and nonemotional stimuli (smaller P300), followed by later increased processing of unpleasant stimuli (larger slow wave [SW]). Results suggest that early disengagement from emotional stimuli may help individuals with moderate-to-severe abuse histories to achieve normal behavioral performance on the emotion-word Stroop task. Additionally, regardless of analytic approach, adults with elevated levels of childhood abuse exhibited prolonged engagement (larger SW) specifically with unpleasant stimuli. Present results demonstrate attention bias patterns in adults with a history of childhood abuse and clarify the time course of attention bias. Results are discussed in the context of potential treatment implications.

The moderating role of socioeconomic status on level of responsibility, executive functioning, and cortical thinning during adolescence

Brain development is exquisitely sensitive to psychosocial experiences, with implications for neurodevelopmental trajectories, for better or worse. The premise of this investigation was that the level of responsibility in adolescence may relate to brain structure and higher-order cognitive functions. In a sample of 108 adolescents, we focused on cortical thickness (using FreeSurfer) as an indicator of neurodevelopment in regions previously implicated in executive functioning (EF) and examined performance on an EF task outside of the scanner, in the context of level of responsibility. We further investigated whether socioeconomic status (SES) and family stress moderated the relationship between responsibility and brain structure or EF. Findings revealed that greater responsibility was related to thinner left precuneus and right middle frontal cortex. In lower SES adolescents, greater responsibility predicted thinner left precuneus and right middle frontal cortex, which have been consistently implicated in EF. Higher SES adolescents did not show structural differences related to responsibility, however, they did exhibit better EF performance. It may be that circumstances surrounding the need for greater responsibility in lower SES households are detrimental to neurodevelopment compared to higher SES households. Alternatively, responsibility may act as a protective factor that bolsters cortical thinning in regions related to EF.

Spatial patterns of intrinsic brain activity and functional connectivity in facial synkinesis patients

Objectives: As one of the most objectionable sequelae of facial paralysis, patients with facial synkinesis are more likely to be depressed and have lower quality of life than other facial paralysis patients. However, there is no research on the spatial patterns of intrinsic brain activity and functional connectivity in these patients. The objective of this study was to investigate the spatial patterns and cerebral plasticity of facial synkinesis patients.Methods: A total of 20 facial synkinesis patients (18 men and 2 women; mean age: 33.35 ± 6.97 years old) and 19 healthy controls (17 men and 2 women; mean age: 33.21 ± 6.75 years old) were enrolled in this study. resting-state functional magnetic resonance imaging (rs-fMRI) data were collected, and the amplitude of low frequency fluctuation (ALFF), regional homogeneity (ReHo), and degree centrality (DC) were calculated for each participant. Two-sample t-tests were performed to compare the ALFF, ReHo, and DC maps between the two groups.Results: Compared with the healthy controls, facial synkinesis patients exhibited decreased ALFF in the fusiform gyrus, lingual gyrus, parahippocampal gyrus, triangular inferior frontal gyrus, precentral gyrus, postcentral gyrus, cingulate gyrus, superior frontal gyrus, precuneus, caudate nucleus and thalamus; decreased ReHo in the cingulate gyrus, superior frontal gyrus, insula, superior temporal gyrus, orbital middle frontal gyrus, caudate nucleus and thalamus; and decreased DC in the frontal lobe, insula, cingulate gyrus, superior temporal gyrus, lenticular putamen, hippocampus and parahippocampal gyrus. We found significant overlap in the superior frontal gyrus across the ALFF, ReHo and DC analyses.Conclusions: In facial synkinesis patients, the neurological activity in brain areas is reduced and the local synchronization in motion-related brain regions is decreased. The superior frontal gyrus could be a crucial region in the unique spatial patterns of intrinsic brain activity and functional connectivity in these patients.

Developmental trajectories to reduced activation of positive valence systems: A review of biological and environmental contributions

Reduced activation of positive valence systems (PVS), including blunted neural and physiological responses to pleasant stimuli and rewards, has been shown to prospectively predict the development of psychopathology. Yet, little is known about how reduced PVS activation emerges across development or what implications it has for prevention. We review genetic, temperament, parenting, and naturalistic and laboratory stress research on neural measures of PVS and outline developmentally-informed models of trajectories of PVS activation. PVS function is partly heritable and appears to reflect individual differences in early-emerging temperament traits. Although lab-induced stressors blunt PVS activation, effects of parenting and naturalistic stress on PVS are mixed and depend on the type of stressor, developmental timing, and interactions amongst risk factors. We propose that there may be multiple, dynamic developmental trajectories to reduced PVS activation in which combinations of genes, temperament, and exposure to severe, prolonged, or uncontrollable stress may exert direct and interactive effects on PVS function. Critically, these risk factors may alter PVS developmental trajectories and/or PVS sensitivity to proximal stressors. Distinct factors may converge such that PVS activation proceeds along a typical, accelerated, chronically low, or stress-reactive trajectory. Finally, we present directions for future research with translational implications.

Disruptive Behavior Problems, Callous-Unemotional Traits, and Regional Gray Matter Volume in the Adolescent Brain and Cognitive Development Study

BACKGROUND

Neurobiological differences linked to socioemotional and cognitive processing are well documented in youths with disruptive behavior disorders (DBDs), especially youths with callous-unemotional (CU) traits. The current study expanded this literature by examining gray matter volume (GMV) differences among youths with DBD with CU traits (DBDCU+), youths with DBD without CU traits (DBD-only), and youths that were typically developing (TD).

METHODS

Data were from the first full sample release of the Adolescent Brain and Cognitive Development Study (mean age = 9.49 years; 49% female). We tested whether the GMVs of 11 regions of interest selected a priori differentiated between our 3 groups: DBDCU+ (n = 288), DBD-only (n = 362), and TD (n = 915). Models accounted for demographic confounders, attention-deficit/hyperactivity disorder, and intracranial volume. We examined two potential moderators of the relationship between GMVs and group membership: sex and clinically significant anxiety (i.e., primary vs. secondary CU traits subtype).

RESULTS

Youths in the DBDCU+ group had lower right amygdala GMV, and youths in the DBD-only group had lower bilateral amygdala GMV relative to TD youths. Youths in the DBDCU+ group had lower bilateral hippocampal GMV, and youths in the DBD-only group had lower left hippocampal GMV relative to TD youths. Youths in the DBDCU+ group evidenced lower left insula GMV relative to TD youths. Finally, youths in the DBD-only group had lower left superior frontal gyrus and lower right caudal anterior cingulate cortex GMVs relative to TD youths. There was no moderation of associations between GMV and group membership by sex.

CONCLUSIONS

Our findings implicate structural aberrations in both the amygdala and hippocampus in the etiology of DBDs, with minimal evidence for differences based on the presence or absence of CU traits.

Bullying Victimization and Trauma

Bullying victimization and trauma research traditions operate quite separately. Hence, it is unclear from the literature whether bullying victimization should be considered as a form of interpersonal trauma. We review studies that connect bullying victimization with symptoms of PTSD, and in doing so, demonstrate that a conceptual understanding of the consequences of childhood bullying needs to be framed within a developmental perspective. We discuss two potential diagnoses that ought to be considered in the context of bullying victimization: (1) developmental trauma disorder, which was suggested but not accepted as a new diagnosis in the DSM-5 and (2) complex post-traumatic stress disorder, which has been included in the ICD-11. Our conclusion is that these frameworks capture the complexity of the symptoms associated with bullying victimization better than PTSD. We encourage practitioners to understand how exposure to bullying interacts with development at different ages when addressing the consequences for targets and when designing interventions that account for the duration, intensity, and sequelae of this type of interpersonal trauma.

Depression Severity Over 27 Months in Adolescent Girls Is Predicted by Stress-Linked Cortical Morphology

BACKGROUND

Evidence supports the notion that early-life stress and trauma impact cortical development and increase vulnerability to depression. However, it remains unclear whether common stressful life events in community-dwelling adolescents have similar consequences for cortical development.

METHODS

A total of 232 adolescent girls (mean age 15.29 ± 0.65 years) were assessed with the Stressful Life Events Schedule (a semistructured interview of stressors in the previous 9 months) and underwent a magnetic resonance imaging scan. FreeSurfer 5.3.0 was used to perform whole-brain surface-based morphometry. Dysphoria was assessed at the time of imaging and prospectively at three 9-month follow-up appointments using the Inventory of Depression and Anxiety Symptoms II.

RESULTS

At least one stressful life event was reported in 90% of the adolescent participants during the 9 months preceding imaging. Greater burden of recent life stress was associated with less left precuneus and left postcentral cortical thickness and smaller left superior frontal and right inferior parietal volume (all p < .05 after multiple comparisons correction). Left precuneus thickness in the stress-associated cluster significantly predicted dysphoria for 27 months after imaging controlling for prior dysphoria (β = -.11, p = .004). Left precuneus cortical thickness accounted for 17.0% of the association between stress and dysphoric mood for 27 months after imaging (β = .04, p = .05).

CONCLUSIONS

Consistent with evidence from imaging studies of trauma-exposed youths and preclinical stress models, a heavy burden of recent common life stress in community-dwelling adolescent girls was associated with altered frontal/parietal cortical morphology. Stress-linked precuneus cortical thickness represents a candidate prospective biomarker of adolescent depression.

Subcortical structural variations associated with low socioeconomic status in adolescents

Low socioeconomic status (SES) is associated with a higher probability of multiple exposures (e.g., neighborhood violence, poor nutrition, housing instability, air pollution, and insensitive caregiving) known to affect structural development of subcortical brain regions that subserve threat and reward processing, however, few studies have examined the relationship between SES and such subcortical structures in adolescents. We examined SES variations in volume and surface morphometry of subcortical regions. The sample comprised 256 youth in eighth grade (mean age = 13.9 years), in whom high dimensional deformation mapping of structural 3T magnetic resonance imaging scans was performed. Vertex‐wise linear regression analyses examined associations between income to poverty ratio and surfaces of the hippocampus, amygdala, thalamus, caudate, putamen, nucleus accumbens and pallidum, with the covariates age, pubertal status, and intracranial volume. Given sex differences in pubertal development and subcortical maturation at this age, the analyses were stratified by sex. Among males, who at this age average an earlier pubertal stage than females, the relationship between SES and local shape variation in subcortical regions was almost entirely positive. For females, the relationship between SES and local shape variation was negative. Racial identity was associated with SES in our sample, however supplementary analyses indicated that most of the associations between SES and subcortical structure were independent of it. Although these cross‐sectional results are not definitive, they are consistent with a scenario where low SES delays structural maturation of subcortical regions involved with threat and reward processing. Future longitudinal studies are needed to test this hypothesis.

Stress and the brain: Perceived stress mediates the impact of the superior frontal gyrus spontaneous activity on depressive symptoms in late adolescence

Identifying factors for the prediction of depression is a long-standing research topic in psychiatry and psychology. Perceived stress, which reflects the tendency to appraise one's life situations as stressful and overwhelming, has emerged as a stable predictor for depressive symptoms. However, the neurobiological bases of perceived stress and how perceived stress influences depressive symptoms in the healthy brain remain largely unknown. Here, we investigated these issues in 217 healthy adolescents by estimating the fractional amplitude of low-frequency fluctuations (fALFFs) via resting-state functional magnetic resonance imaging. A whole-brain correlation analysis showed that higher levels of perceived stress were associated with greater fALFF in the left superior frontal gyrus (SFG), which is a core brain region for cognitive control and emotion regulation-related processes. Mediation analysis further indicated that perceived stress mediated the link between the fALFF in the left SFG and depressive symptoms. Importantly, our results remained significant even when excluding the influences of head motion, anxiety, SFG gray matter structure, and school environment. Altogether, our findings suggested that the fALFF in the left SFG is a neurofunctional marker of perceived stress in adolescents and revealed a potential indirect effect of perceived stress on the association between the SFG spontaneous activity and depressive symptoms.

Pubertal development mediates the association between family environment and brain structure and function in childhood

Psychosocial acceleration theory suggests that pubertal maturation is accelerated in response to adversity. In addition, suboptimal caregiving accelerates development of the amygdala-medial prefrontal cortex circuit. These findings may be related. Here, we assess whether associations between family environment and measures of the amygdala-medial prefrontal cortex circuit are mediated by pubertal development in more than 2000 9- and 10-year-old children from the Adolescent Brain Cognitive Development Study (http://dx.doi.org/10.15154/1412097). Using structural equation modeling, demographic, child-reported, and parent-reported data on family dynamics were compiled into a higher level family environment latent variable. Magnetic resonance imaging preprocessing and compilations were performed by the Adolescent Brain Cognitive Development Study's data analysis core. Anterior cingulate cortex (ACC) thickness, area, white matter fractional anisotropy, amygdala volume, and cingulo-opercular network-amygdala resting-state functional connectivity were assessed. For ACC cortical thickness and ACC fractional anisotropy, significant indirect effects indicated that a stressful family environment relates to more advanced pubertal stage and more mature brain structure. For cingulo-opercular network-amygdala functional connectivity, results indicated a trend in the expected direction. For ACC area, evidence for quadratic mediation by pubertal stage was found. Sex-stratified analyses suggest stronger results for girls. Despite small effect sizes, structural measures of circuits important for emotional behavior are associated with family environment and show initial evidence of accelerated pubertal development.

Psychosis and urbanicity: a review of the recent literature from epidemiology to neurourbanism

PURPOSE OF REVIEW

Epidemiological studies associate city living with an elevated psychosis risk. Urban (social/economic) stress and exposure to environmental toxins, pollution or disease agents have been proposed to underlie this association. This review provides an update on the recent evidence (May 2017 - November 2018).

RECENT FINDINGS

Of 647 screened studies, 17 on: urbanicity-psychosis associations in worldwide high, middle and low-income countries; explanatory mechanisms, including nature exposure, social and economic stressors and genetic risk; urbanicity effects on the brain and coping; and urbanicity and resources, were included. The reviewed evidence revealed complex patterns of urbanicity-psychosis associations with considerable international variation within Europe and between low, middle and high-income countries worldwide. Social and economic stressors (e.g. migration, ethnic density and economic deprivation), nature exposure and access to resources could only explain part of the urbanicity effects. Risk factors differed between countries and between affective and non-affective psychosis.

SUMMARY

Urbanicity-psychosis associations are heterogeneous and driven by multiple risk and protective factors that seem to act differently in different ethnic groups and countries. Interdisciplinary research combining approaches, for example from experimental neuroscience and epidemiology, are needed to unravel specific urban mechanisms that increase or decrease psychosis risk.

DRD2 methylation and regional grey matter volumes in young adult offspring from families at ultra-high risk for alcohol dependence

Dopaminergic alteration is a prominent feature in those with AD and may influence brain development in those with a family history of AD. MRI scans (3T) from 43 HR offspring (27.4 ± 3.6 years) and 45 controls (24.5 ± 4.1 years) provided whole brain (WB) and region of interest (ROI) analyses. The VBM8 toolbox was used for WB analysis (threshold p < 0.005; cluster = 100 voxels); the MarsBaR ROI toolbox provided region of interest data. Pyrosequencing of CpG sites within the DRD2 gene was performed. DRD2 methylation was significantly increased in association with familial high-risk status. Significant familial risk group differences were seen with HR individuals showing reduced volume of the Left Inferior Temporal, Left Fusiform and Left Insula regions relative to LR controls. These regions have previously been linked to social cognition. DRD2 methylation was negatively related to grey matter volumes in these regions. Because these regions, have been previously linked to facial affect perception and social cognition, lesser grey matter volumes in individuals at high-risk for developing AD suggests that neural underpinnings of social cognitive impairment may be a premorbid risk factors for AD.

Stress exposures, neurodevelopment and health measures in the ABCD study

The Adolescent Brain Cognitive Development (ABCD) Study, a large, longitudinal study of brain development and child health, is uniquely positioned to explore relationships among stress, neurodevelopment, and psychiatric symptomatology, including substance use and addiction. There is much we do not know about how adverse experiences affect the developing brain and cognitive, social, emotional, and academic outcomes. The data collected by the ABCD Study will allow the examination of the relationships among these variables in adolescence, including the effects of stressors (e.g., abuse, neglect, household challenges, parental substance use) on psychological adjustment and other stress responses. A comprehensive protocol that includes physical and mental health, substance use, culture and environment, neurocognitive assessments, biospecimen analyses, and structural and functional neuroimaging will provide opportunities for learning about the impacts of stressors on health and other outcomes in the context of adolescent development. This knowledge could lead to the development of interventions that reduce or even reverse the impacts of stressors.

How early media exposure may affect cognitive function: A review of results from observations in humans and experiments in mice

Attention deficit hyperactivity disorder (ADHD) is now among the most commonly diagnosed chronic psychological dysfunctions of childhood. By varying estimates, it has increased by 30% in the past 20 years. Environmental factors that might explain this increase have been explored. One such factor may be audiovisual media exposure during early childhood. Observational studies in humans have linked exposure to fast-paced television in the first 3 years of life with subsequent attentional deficits in later childhood. Although longitudinal and well controlled, the observational nature of these studies precludes definitive conclusions regarding a causal relationship. As experimental studies in humans are neither ethical nor practical, mouse models of excessive sensory stimulation (ESS) during childhood, akin to the enrichment studies that have previously shown benefits of stimulation in rodents, have been developed. Experimental studies using this model have corroborated that ESS leads to cognitive and behavioral deficits, some of which may be potentially detrimental. Given the ubiquity of media during childhood, these findings in humansand rodents perhaps have important implications for public health.