Default Mode Network Maturation and Environmental Adversities During Childhood

The impact of sleep problems during late childhood on internalizing problems in early-mid adolescence

OBJECTIVES

Sleep and internalizing problems escalate during adolescence and can negatively impact long-term health. However, the directionality of this risk-relationship remains poorly understood within a developmental context. The current study aimed to determine the directionality of this relationship in adolescents with no history of psychiatric disorder and whether sex at birth played a role in this relationship.

METHODS

We used data from the Adolescent Brain Cognitive Development, an ongoing multisite longitudinal US study, that covered four waves (W1:9-11 years; W2:10-12 years; W3:11-13 years; W4:12-14 years). Analyses included 3,128 youth (50.99%girls) with no past or current psychiatric disorders at W1. The Sleep Disturbance Scale for Children and the Child Behavior Checklist were used to measure sleep and internalizing problems. Cross-lagged panel models were used to evaluate the cross-lagged relationships across waves.

RESULTS

The sleep-internalizing cross-lagged relationship was unidirectional, with medium-large effect sizes: greater total sleep problems were associated with more severe internalizing problems at later waves (W2➔W3, coefficient = 0.052, p = .021; W3➔W4, coefficient = 0.091, p < .001), with problems in initiating and maintaining sleep predicting internalizing problems early on. Girls showed greater sleep-internalizing risk than boys.

CONCLUSIONS

Sleep-internalizing relationships change across adolescence, becoming significant and more specific from early to mid-adolescence. Sleep interventions delivered in early adolescence, to girls in particular, may have a positive short and long-term impact on internalizing outcomes.

Advances in the fMRI analysis of the default mode network: a review

The default mode network (DMN) is a singular pattern of synchronization between brain regions, usually observed using resting-state functional magnetic resonance imaging (rs-fMRI) and functional connectivity analyses. In comparison to other brain networks that are primarily involved in attentional-demanding tasks (such as the frontoparietal network), the DMN is linked with self-referential activities, and alterations in its pattern of connectivity have been related to a wide range of disorders. Structural connectivity analyses have highlighted the vital role of the posterior cingulate cortex and the precuneus as integrative hubs, and advanced parcellation methods have further contributed to elucidate the DMN's regions, enriching its explanatory potential across cognitive functions and dysfunctions. Interestingly, the study of its temporal characteristics - the specific frequency spectrum of BOLD signal oscillations -, its developmental trajectory over the course of life, and its interaction with other networks, provides new insight into the DMN's defining features. In this context, this review aims to synthesize the state of the art in the study of the DMN to provide the most updated findings to anyone interested in its research. Finally, some weaknesses in the current state of knowledge and some interesting lines of work for further progress in the study of the DMN are presented.

Cortical Surface Area Profile Mediates Effects of Childhood Disadvantage on Later-Life General Cognitive Ability

OBJECTIVES

Childhood disadvantage is associated with lower general cognitive ability (GCA) and brain structural differences in midlife and older adulthood. However, the neuroanatomical mechanisms underlying childhood disadvantage effects on later-life GCA remain poorly understood. Although total surface area (SA) has been linked to lifespan GCA differences, total SA does not capture the nonuniform nature of childhood disadvantage effects on neuroanatomy, which varies across unimodal and transmodal cortices. Here, we examined whether cortical SA profile-the extent to which the spatial patterning of SA deviates from the normative unimodal-transmodal cortical organization-is a mediator of childhood disadvantage effects on later-life GCA.

METHODS

In 477 community-dwelling men aged 56-72 years old, childhood disadvantage index was derived from four indicators of disadvantages and GCA was assessed using a standardized test. Cortical SA was obtained from structural magnetic resonance imaging. For cortical SA profile, we calculated the spatial similarity between maps of individual cortical SA and MRI-derived principal gradient (i.e., unimodal-transmodal organization). Mediation analyses were conducted to examine the indirect effects of childhood disadvantage index through cortical SA profile on GCA.

RESULTS

Around 1.31% of childhood disadvantage index effects on later-life GCA were mediated by cortical SA profile, whereas total SA did not. Higher childhood disadvantage index was associated with more deviation of the cortical SA spatial patterning from the principal gradient, which in turn related to lower later-life GCA.

DISCUSSION

Childhood disadvantage may contribute to later-life GCA differences partly by influencing the spatial patterning of cortical SA in a way that deviates from the normative cortical organizational principle.

Complex emotion processing and early life adversity in the Healthy Brain Network sample

OBJECTIVE

Early life adversity (ELA) has shown to have negative impacts on mental health. One possible mechanism is through alterations in neural emotion processing. We sought to characterize how multiple indices of ELA were related to naturalistic neural socio-emotional processing.

METHOD

In 521 5-15-year-old participants from the Healthy Brain Network Biobank, we identified scenes that elicited activation of the Default Mode Network (DMN), Ventral Attention Network (VAN), Cingulo-Opercular Network (CON) and amygdala, all of which are networks shown to be associated with ELA. We used linear regression to examine associations between activation and ELA: negative parenting, social status, financial insecurity, neighborhood disadvantage, negative experiences, and parent psychopathology.

RESULTS

We found DMN, VAN, CON and amygdala activation during sad/emotional, bonding, action, conflict, sad, or fearful scenes. Greater inconsistent discipline was associated with greater VAN activation during sad or emotional scenes.

CONCLUSION

Findings suggest that the DMN, VAN, CON networks and the amygdala support socio-emotional processing consistent with prior literature. Individuals who experienced inconsistent discipline may have greater sensitivity to parent-child separation signals. Since no other ELA-activation associations were found, it is possible that unpredictability may be more strongly associated with complex neural emotion processing than socio-economic status or negative life events.

Strengthening through adversity: The hormesis model in developmental psychopathology

BACKGROUND

Employing a developmental psychopathology framework, we tested the utility of the hormesis model in examining the strengthening of children and youth through limited levels of adversity in relation to internalizing and externalizing outcomes within a brain-by-development context.

METHODS

Analyzing data from the Adolescent Brain and Cognitive Development study (N = 11,878), we formed latent factors of threat, deprivation, and unpredictability. We examined linear and nonlinear associations between adversity dimensions and youth psychopathology symptoms and how change of resting-state functional connectivity (rsFC) in the default mode network (DMN) from Time 1 to Time 5 moderates these associations.

RESULTS

A cubic association was found between threat and youth internalizing problems; low-to-moderate family conflict levels reduced these problems. Deprivation also displayed a cubic relation with youth externalizing problems, with moderate deprivation levels associated with fewer problems. Unpredictability linearly increased both problem types. Change in DMN rsFC significantly moderated the cubic link between threat levels and internalizing problems, with declining DMN rsFC levels from Time 1 to Time 5 facilitating hormesis. Hormetic effects peaked earlier, emphasizing the importance of sensitive periods and developmental timing of outcomes related to earlier experiences.

CONCLUSIONS

Strengthening through limited environmental adversity is crucial for developing human resilience. Understanding this process requires considering both linear and nonlinear adversity-psychopathology associations. Testing individual differences by brain and developmental context will inform preventive intervention programming.

The interplay of dopaminergic genotype and parent-child relationship in relation to intra-individual response time variability in preschoolers: A replication study

Intra-individual response time variability (IIRTV) during cognitive performance is increasingly recognized as an important indicator of attentional control (AC) and related brain region function. However, what determinants contribute to preschoolers' IIRTV received little attention. The present study explored the interaction of dopaminergic polygenic composite score (DPCS) and the parent-child relationship in relation to preschoolers' IIRTV. In the initial sample, 452 preschoolers (M age = 5.17, SD = 0.92) participated in the study. The modified Flanker task was used to evaluate children's IIRTV and their parents were requested to complete the Parent-Child Relationship Scale to assess the parent-child relationship (closeness/conflict). DNA data were extracted from children's saliva samples, and a DPCS was created by the number of COMT, DAT1, and DRD2 alleles associated with lower dopamine levels. Results showed that DPCS significantly interacted with the parent-child closeness to impact preschoolers' IIRTV. Specifically, preschoolers with higher DPCS exhibited lower IIRTV under higher levels of the parent-child closeness, and greater IIRTV under lower levels of the parent-child closeness compared to those with lower DPCS, which supported the differential susceptibility theory (DST). A direct replication attempt with 280 preschoolers (M age = 4.80, SD = 0.86) was conducted to investigate whether the results were in accordance with our exploratory outcomes. The interactive effect of DPCS and the parent-child closeness on IIRTV was confirmed. Additionally, the significant interactive effect of DPCS and the parent-child conflict on IIRTV was found in the replication study. The findings indicate that preschoolers' IIRTV, as an indicator of AC and related brain region function, is influenced by the interactions of dopaminergic genotypes and the parent-child relationship. RESEARCH HIGHLIGHTS: We investigated the Gene × Environment mechanism to underline the intra-individual response time variability as an indicator of attentional control (AC) in Chinese preschoolers. Dopaminergic polygenic composite score (COMT, DAT1, and DRD2) interacted with the parent-child relationship to predict preschoolers' intra-individual reaction time variability. A direct replication attempt has been conducted, and the results were in accordance with our exploratory outcomes, which increased the credibility of the present findings. The findings highlight the importance of considering precursors, including polygenic and environmental factors, which contribute to the development of early cognitive performance such as AC.

Brain topology underlying executive functions across the lifespan: focus on the default mode network

Introduction

While traditional neuroimaging approaches to the study of executive functions (EFs) have typically employed task-evoked paradigms, resting state studies are gaining popularity as a tool for investigating inter-individual variability in the functional connectome and its relationship to cognitive performance outside of the scanner.

Method

Using resting state functional magnetic resonance imaging data from the Human Connectome Project Lifespan database, the present study capitalized on graph theory to chart cross-sectional variations in the intrinsic functional organization of the frontoparietal (FPN) and the default mode (DMN) networks in 500 healthy individuals (from 10 to 100 years of age), to investigate the neural underpinnings of EFs across the lifespan.

Results

Topological properties of both the FPN and DMN were associated with EF performance but not with a control task of picture naming, providing specificity in support for a tight link between neuro-functional and cognitive-behavioral efficiency within the EF domain. The topological organization of the DMN, however, appeared more sensitive to age-related changes relative to that of the FPN.

Discussion

The DMN matures earlier in life than the FPN and it ıs more susceptible to neurodegenerative changes. Because its activity is stronger in conditions of resting state, the DMN might be easier to measure in noncompliant populations and in those at the extremes of the life-span curve, namely very young or elder participants. Here, we argue that the study of its functional architecture in relation to higher order cognition across the lifespan might, thus, be of greater interest compared with what has been traditionally thought.

Longitudinal variation in resilient psychosocial functioning is associated with ongoing cortical myelination and functional reorganization during adolescence

Adolescence is a period of dynamic brain remodeling and susceptibility to psychiatric risk factors, mediated by the protracted consolidation of association cortices. Here, we investigated whether longitudinal variation in adolescents' resilience to psychosocial stressors during this vulnerable period is associated with ongoing myeloarchitectural maturation and consolidation of functional networks. We used repeated myelin-sensitive Magnetic Transfer (MT) and resting-state functional neuroimaging (n = 141), and captured adversity exposure by adverse life events, dysfunctional family settings, and socio-economic status at two timepoints, one to two years apart. Development toward more resilient psychosocial functioning was associated with increasing myelination in the anterolateral prefrontal cortex, which showed stabilized functional connectivity. Studying depth-specific intracortical MT profiles and the cortex-wide synchronization of myeloarchitectural maturation, we further observed wide-spread myeloarchitectural reconfiguration of association cortices paralleled by attenuated functional reorganization with increasingly resilient outcomes. Together, resilient/susceptible psychosocial functioning showed considerable intra-individual change associated with multi-modal cortical refinement processes at the local and system-level.

Childhood adversities characterize the heterogeneity in the brain pattern of individuals during neurodevelopment

BACKGROUND

Several factors shape the neurodevelopmental trajectory. A key area of focus in neurodevelopmental research is to estimate the factors that have maximal influence on the brain and can tip the balance from typical to atypical development.

METHODS

Utilizing a dissimilarity maximization algorithm on the dynamic mode decomposition (DMD) of the resting state functional MRI data, we classified subjects from the cVEDA neurodevelopmental cohort (n = 987, aged 6-23 years) into homogeneously patterned DMD (representing typical development in 809 subjects) and heterogeneously patterned DMD (indicative of atypical development in 178 subjects).

RESULTS

Significant DMD differences were primarily identified in the default mode network (DMN) regions across these groups (p < 0.05, Bonferroni corrected). While the groups were comparable in cognitive performance, the atypical group had more frequent exposure to adversities and faced higher abuses (p < 0.05, Bonferroni corrected). Upon evaluating brain-behavior correlations, we found that correlation patterns between adversity and DMN dynamic modes exhibited age-dependent variations for atypical subjects, hinting at differential utilization of the DMN due to chronic adversities.

CONCLUSION

Adversities (particularly abuse) maximally influence the DMN during neurodevelopment and lead to the failure in the development of a coherent DMN system. While DMN's integrity is preserved in typical development, the age-dependent variability in atypically developing individuals is contrasting. The flexibility of DMN might be a compensatory mechanism to protect an individual in an abusive environment. However, such adaptability might deprive the neural system of the faculties of normal functioning and may incur long-term effects on the psyche.

Trait anxiety and corresponding neuromarkers predict internet addiction: A longitudinal study

Background and Aims

The high prevalence of internet addiction (IA) has become a worldwide problem that profoundly affects people's mental health and executive function. Empirical studies have suggested trait anxiety (TA) as one of the most robust predictors of addictive behaviors. The present study investigated the neural and socio-psychological mechanisms underlying the association between TA and IA.

Methods

Firstly, we tested the correlation between TA and IA. Then we investigated the longitudinal influence of TA on IA using a linear mixed effect (LME) model. Secondly, connectome-based predictive modeling (CPM) was employed to explore neuromarkers of TA, and we tested whether the identified neuromarkers of TA can predict IA. Lastly, stressful life events and default mode network (DMN) were considered as mediating variables to explore the relationship between TA and IA.

Findings

A significant positive correlation between TA and IA was found and the high TA group demonstrated higher IA across time. CPM results revealed that the functional connectivity of cognitive control and emotion-regulation circuits and DMN were significantly correlated with TA. Furthermore, a significant association was found between the neuromarkers of TA and IA. Notably, the CPM results were all validated in an independent sample. The results of mediation demonstrated that stressful life events and correlated functional connectivity mediated the association between TA and IA.

Conclusions

Findings of the present study facilitate a deeper understanding of the neural and socio-psychological mechanisms linking TA and IA and provide new directions for developing neural and psychological interventions.

Examining the Role of Socioeconomic Status and Maternal Sensitivity in Predicting Functional Brain Network Connectivity in 5-Month-Old Infants

Infancy is a sensitive period of human brain development that is plastically shaped by environmental factors. Both proximal factors, such as sensitive parenting, and distal factors, such as socioeconomic status (SES), are known predictors of individual differences in structural and functional brain systems across the lifespan, yet it is unclear how these familial and contextual factors work together to shape functional brain development during infancy, particularly during the first months of life. In the current study, we examined pre-registered hypotheses regarding the interplay between these factors to assess how maternal sensitivity, within the broader context of socioeconomic variation, relates to the development of functional connectivity in long-range cortical brain networks. Specifically, we measured resting-state functional connectivity in three cortical brain networks (fronto-parietal network, default mode network, homologous-interhemispheric connectivity) using functional near-infrared spectroscopy (fNIRS), and examined the associations between maternal sensitivity, SES, and functional connectivity in a sample of 5-month-old infants and their mothers (N = 50 dyads). Results showed that all three networks were detectable during a passive viewing task, and that maternal sensitivity was positively associated with functional connectivity in the default mode network, such that infants with more sensitive mothers exhibited enhanced functional connectivity in this network. Contrary to hypotheses, we did not observe any associations of SES with functional connectivity in the brain networks assessed in this study. This suggests that at 5 months of age, maternal sensitivity is an important proximal environmental factor associated with individual differences in functional connectivity in a long-range cortical brain network implicated in a host of emotional and social-cognitive brain processes.

Mediating role of the default mode network on parental acceptance/warmth and psychopathology in youth

Humans are reliant on their caregivers for an extended period of time, offering numerous opportunities for environmental factors, such as parental attitudes and behaviors, to impact brain development. The default mode network is a neural system encompassing the medial prefrontal cortex, posterior cingulate cortex, precuneus, and temporo-parietal junction, which is implicated in aspects of cognition and psychopathology. Delayed default mode network maturation in children and adolescents has been associated with greater general dimensional psychopathology, and positive parenting behaviors have been suggested to serve as protective mechanisms against atypical default mode network development. The current study aimed to extend the existing research by examining whether within- default mode network resting-state functional connectivity would mediate the relation between parental acceptance/warmth and youth psychopathology. Data from the Adolescent Brain and Cognitive Development study, which included a community sample of 9,366 children ages 8.9-10.9 years, were analyzed to test this prediction. Results demonstrated a significant mediation, where greater parental acceptance/warmth predicted greater within- default mode network resting-state functional connectivity, which in turn predicted lower externalizing, but not internalizing symptoms, at baseline and 1-year later. Our study provides preliminary support for the notion that positive parenting behaviors may reduce the risk for psychopathology in youth through their influence on the default mode network.

Normal development of the brain: a survey of joint structural-functional brain studies

Joint structural-functional (S-F) developmental studies present a novel approach to address the complex neuroscience questions on how the human brain works and how it matures. Joint S-F biomarkers have the inherent potential to model effectively the brain's maturation, fill the information gap in temporal brain atlases, and demonstrate how the brain's performance matures during the lifespan. This review presents the current state of knowledge on heterochronous and heterogeneous development of S-F links during the maturation period. The S-F relationship has been investigated in early-matured unimodal and prolonged-matured transmodal regions of the brain using a variety of structural and functional biomarkers and data acquisition modalities. Joint S-F unimodal studies have employed auditory and visual stimuli, while the main focus of joint S-F transmodal studies has been resting-state and cognitive experiments. However, nonsignificant associations between some structural and functional biomarkers and their maturation show that designing and developing effective S-F biomarkers is still a challenge in the field. Maturational characteristics of brain asymmetries have been poorly investigated by the joint S-F studies, and the results were partially inconsistent with previous nonjoint ones. The inherent complexity of the brain performance can be modeled using multifactorial and nonlinear techniques as promising methods to simulate the impact of age on S-F relations considering their analysis challenges.

The cognitive basis of psychosocial impact in COVID-19 pandemic. Does it encircle the default mode network of the brain? A pragmatic proposal

Epigenetics, hypothalamic-pituitary axes, environmental and metabolic influences, and transgenerational plasticity govern social behavior. Cognitive research considers the brain's default mode network (DMN) as a central hub that integrates various cognitive and social processing domains responsible for emotion perception, empathy, theory of mind, and morality. Hence, DMN is regarded as the "social brain." Upsurge in social turmoil, social anxiety, panic, depression, post-traumatic stress, hoarding, herd behavior, substance and behavioral addictions, sexual abuse, and violence in the time of the COVID-19 pandemic are intricately related to personality traits resulting in disruptive social cognition and social behavior, conceptualized as the result of unsettling and disruption of the functional nexus of the DMN. Considering overt and conspicuous display of neuroticism during the current pandemic, its impact upon modulation of the DMN functional nexus and the DMN itself, and the potential to presage cognitive impairment in the future, the authors caution that an increase in the global burden of dementia may be one of the long-term ramifications of COVID-19. Social behavior, a functional derivative of the DMN, can strikingly affect the functional nexus of DMN and the DMN itself, in a centripetal way via the phenomenon called "Experience-Dependent Plasticity," with long-term consequences. In this review, we intend to 1) decipher the association between social cognition and social behavior with the DMN, in time of COVID-19; and to 2) discuss the prospective aftermath of disrupted social behavior during the pandemic on modulation/alteration of functional connectomes of DMN or the DMN itself in the time ahead.

Bridging Anxiety and Depression: A Network Approach in Anxious Adolescents

BACKGROUND

The phenomenology and neurobiology of depressive symptoms in anxious youth is poorly understood.

METHODS

Association networks of anxiety and depressive symptoms were developed in adolescents with generalized anxiety disorder (GAD; N=52, mean age: 15.4±1.6 years) who had not yet developed major depressive disorder. Community analyses were used to create consensus clusters of depressive and anxiety symptoms and to identify "bridge" symptoms between the clusters. In a subset of this sample (n=39), correlations between cortical thickness and depressive symptom severity was examined.

RESULTS

Ten symptoms clustered into an anxious community, 5 clustered into a depressive community and 5 bridged the two communities: impaired schoolwork, excessive weeping, low self-esteem, disturbed appetite, and physical symptoms of depression. Patients with more depressive cluster burden had altered cortical thickness in prefrontal, inferior and medial parietal (e.g., precuneus, supramarginal) regions and had decreases in cortical thickness-age relationships in prefrontal, temporal and parietal cortices.

LIMITATIONS

Data are cross-sectional and observational. Limited sample size precluded secondary analysis of comorbidities and demographics.

CONCLUSIONS

In youth with GAD, a sub-set of symptoms not directly related to anxiety bridge anxiety and depression. Youth with greater depressive cluster burden had altered cortical thickness in cortical structures within the default mode and central executive networks. These alternations in cortical thickness may represent a distinct neurostructural fingerprint in anxious youth with early depressive symptoms. Finally, youth with GAD and high depressive symptoms had reduced age-cortical thickness correlations. The emergence of depressive symptoms in early GAD and cortical development may have bidirectional, neurobiological relationships.

Impact of preweaning stress on long-term neurobehavioral outcomes in Sprague-Dawley rats: Differential effects of barren cage rearing, pup isolation, and the combination

Two developmental stressors were compared in preweaning rats exposed to either one stressor or both. Stressors were barren cage rearing or maternal separation (pup isolation). 40 gravid Sprague-Dawley CD/IGS rats were randomly assigned to two cage conditions: standard (Std) cage or barren cage (Bar), 20 litters/condition throughout gestation and lactation. After delivery, litters were randomly culled to 4 males and 4 females. The second stressor was maternal separation: Two male/female pairs per litter were isolated from their dam 4 h/day (Iso) and two pairs were not (Norm). Hence, there were 4 conditions: Std-Norm, Std-Iso, Bar-Norm, and Bar-Iso. One pair/litter/stress condition received the following: elevated zero-maze (EZM), open-field, swim channel, Cincinnati water maze, conditioned fear, and open-field with methamphetamine challenge. The second pair/litter/condition received the light-dark test, swim channel, Morris water maze, forced swim, and EZM with diazepam challenge. Barren rearing reduced EZM time-in-open, whereas isolation rearing reduced open-field activity in males and increased it in females. Effects on straight channel swimming were minor. In the Cincinnati water maze test of egocentric learning, isolation rearing increased errors whereas barren cage housing reduced errors in combination with normal rearing. Barren cage with maternal separation (pup isolation) increased Cincinnati water maze escape latency but not errors. Barren cage housing reduced hyperactivity in response to methamphetamine. Isolation rearing increased time in open in the EZM after diazepam challenge. Trends were seen in the Morris water maze. These suggested that barren cage and isolation rearing in combination reduced latency on acquisition on days 1 and 2 in males, whereas females had increased latency on days 2 and 3. Combined exposure to two developmental stressors did not induce additive or synergistic effects, however the data show that these stressors had long-term effects with some evidence that the combination of both caused effects when either stressor alone did not, but synergism was not observed.

Association between spontaneous activity of the default mode network hubs and leukocyte telomere length in late childhood and early adolescence

The impact of early life stress on mental health and telomere length shortening have been reported. Changes in brain default mode network (DMN) were found to be related to a myriad of psychiatric conditions in which stress may play a role. In this context, family environment and adverse childhood experiences (ACEs) are potential causes of stress. This is a hypothesis-driven study focused on testing two hypotheses: (i) there is an association between telomere length and the function of two main hubs of DMN: the posterior cingulate cortex (PCC) and the medial prefrontal cortex (mPFC); (ii) this association is modulated by family environment and/or ACEs. To the best of our knowledge, this is the first study investigating these hypotheses. Resting-state functional magnetic resonance imaging data and blood sample were collected from 389 subjects (6-15 age range). We assessed DMN fractional amplitude of low-frequency fluctuations (fALFF) and leukocyte telomere length (LTL). We fitted general linear models to test the main effects of LTL on DMN hubs and the interaction effects with Family Environment Scale (FES) and ACEs. The results did not survive a strict Bonferroni correction. However, uncorrected p-values suggest that LTL was positively correlated with fALFF in PCC and a FES interaction between FES and LTL at mPFC. Although marginal, our results encourage further research on the interaction between DMN hubs, telomere length and family environment, which may play a role on the biological embedding of stress.