Researchers have found evidence to suggest that i children exposed to high levels of early childhood adversity (ELA) show an accelerated pattern of brain development during the preschool years. When exposed to ELA, such as to the mother's mental and physical health problems during pregnancy, the baby's brain undergoes accelerated development to adapt to adverse circumstances.
I study “The influence of early-life adversity on the coupling of structural and functional brain connectivity across childhood” was published in Nature Mental Health.
ELA: here are the consequences
This accelerated pace of brain development could lead to a greater risk of adverse cognitive and mental health outcomes. ELA exposure is a recognized risk factor for poor health outcomes later in life. This includes an increased risk of cognitive impairment and the development of mental health disorders such as major depressive disorders.
Exposure to ELA in the prenatal period triggers changes in the pace of brain development during childhood, most evident during the preschool period, a crucial time window in which experience-dependent learning and adaptation set the stage for future brain function.
Previous studies suggest that “accelerated brain development” is a mechanism of adaptation to early childhood challenges and may mediate the association between ELA and poor mental health and cognitive outcomes.
To effectively quantify the impact of ELA, the research team adopted a scoring framework created by Professor Patricia Silveira at McGill University, to produce a composite ELA score that considered factors that extend across the population.
These factors focused on exposures experienced before birth, including the mother's mental and physical health during pregnancy, as well as family structure and financial circumstances. When we add or combine several risk factors, we get a better prediction of a child's outcome.
Using this composite score, the study team stratified the GUSTO cohort into different levels of cumulative ELA exposure. The pace of brain development was then examined in children exposed to different levels of ELA.
To model the pace of brain development during childhood, the study team used multimodal MRI scans from the GUSTO birth cohort. These MRI brain scans were acquired from 549 children at three time points, aged 4.5, 6.0, and 7.5 years, allowing the study team to examine the link between ELA and brain development longitudinally.
Since most mental health disorders have roots in childhood, studying developmental trajectories longitudinally is highly relevant.
In this study, a measure combining structural connectivity and functional connectivity of the brain was used to provide information on the association between brain structure and function. This measure, known as structure-function coupling (SC-FC), reflects a child's potential for neuroplasticity, the brain's ability to adapt and reorganize to learn, recover from injury, and adapt to new experiences.
In early childhood, the brain is expected to be less specialized and more adaptable, corresponding to a decreasing trajectory of SC-FC throughout childhood.
Led by Dr Tan Ai Peng, principal investigator at A*STAR's Institute of Clinical Sciences (SICS) and physician at National University Hospital, together with Dr Chan Shi Yu, researcher at A*STAR's SICS, the study found that exposure to high levels of ELA is linked to a more rapid decline in SC-FC between 4.5 and 6 years, indicating accelerated brain development.
This accelerated pattern of brain development is likely an adaptive mechanism when exposed to environmental cues that require “maturity.” While this is intended to be a “protective mechanism” against adversity, it has long-term negative implications as it results in a shorter window of neuroplasticity and adaptive learning. In particular, the results of this study identify the period between ages 4.5 and 6 as a potential window for early intervention to improve outcomes for children exposed to ELA.
“Our study provided evidence that exposure to early childhood challenges influences the pace of brain development during childhood. This, in turn, has significant effects on future cognitive and mental health outcomes. If we can develop screening tools to detect accelerated brain development, we may be able to implement interventions earlier and prevent the cascading consequences of accelerated brain development for mental health,” said Dr. Tan Ai Peng.
Looking ahead, researchers have already identified important areas for future investigation, determining whether the effects of ELA on accelerated brain development during childhood set the stage for premature brain aging in later life and the effectiveness of intervention strategies that could mitigate the effects of ELA. exposure such as promoting psychological resilience through cognitive behavioral therapy.
Adversity in early life is associated with poorer health in adulthood, an association explained, at least in part, by greater engagement in health risk behaviors (HRB). In this review, we argue that it influences brain development in ways that increase the likelihood of engaging in HRB.
ELA alters the neural circuits underlying cognitive control and emotional processing, including networks involved in threat and reward processing. These neural changes are psychologically and behaviorally associated with heightened emotional reactivity, reduced reward reactivity, decreased emotion regulation, and increased delay discounting.
These adaptations to ELA have then been shown to be associated with an increased risk of smoking cigarettes, drinking alcohol, and eating foods high in fat and sugar. Furthermore, we explore how HRBs affect the brain in ways that reinforce addiction and further explain HRB clustering.
Early life adversity involves exposure to environmental circumstances during childhood or adolescence that may require significant psychologi
cal, behavioral, or neurobiological adaptation on the part of the average child. It is associated with poorer health in adulthood, an association explained, at least in part, by greater engagement in health risk behaviors (HRB). In this review, we argue that such adversities influence brain development in ways that increase the likelihood of engaging in HRB.
A recent analysis of data from the National Health Interview Survey revealed that 50% of adults had at least one chronic disease and 25% had two or more of the ten leading causes of death and disability in the United States.
Social determinants and socially shaped HRBs, including tobacco and alcohol use, unhealthy dietary patterns, and physical inactivity drive the chronic disease burden observed in the United States. Often starting during childhood, adolescence, and early adulthood, these highly prevalent HRBs are known to cluster within individuals and populations.
Given the prevalence of chronic diseases, a greater understanding of the mechanisms linking ELAs to HRBs and chronic disease risk has the potential to make a significant contribution to public health by highlighting new intervention targets.
Given that certain types of eating behaviors such as those we focus on in the paper fit neatly into an addiction model, and that ELA is associated with poor diet as well as obesity, we focus on unhealthy eating behavior as a route to obesity, despite the fact that physical inactivity and other factors also contribute to obesity.
Because obesity is often used as an indicator of eating behavior, in this article the neurobiological evidence we present includes both eating behaviors and differences between obese and non-obese populations.
Next, we review existing evidence of how ELA influences these neurodevelopmental processes and discuss how these neural adaptations are associated with psychological and behavioral factors that may increase the likelihood of engaging in HRB.
Existing evidence suggests that children exposed to forms of ELA characterized by threat (e.g., exposure to violence) show a heightened neural response to threat cues, particularly in the amygdala and other nodes of the salience network.
While these adaptations likely help children avoid danger, they come at a cost. For example, specificity is traded for sensitivity, leading to greater emotional reactivity to a wide range of potential threats and more false alarms among children raised in threatening environments.
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