Adversity early in life tends to affect a child’s executive function skills — their ability to focus, for example, or organize tasks.
Experiences such as poverty, residential instability, or parental divorce or substance abuse, also can lead to changes in a child’s brain chemistry, muting the effects of stress hormones.
These hormones rise to help us face challenges, stress or to simply “get up and go.”
Together, these impacts on executive function and stress hormones create a snowball effect, adding to social and emotional challenges that can continue through childhood.
A new University of Washington study examines how adversity can change the ways children develop.
“This study shows how adversity is affecting multiple systems inside a child,” said the study’s lead author, Liliana Lengua, a UW professor of psychology and director of the Center for Child and Family Well-Being.
“The disruption of multiple systems of self-control, both intentional planning efforts and automatic stress-hormone responses, sets off a cascade of neurobiological effects that starts early and continues through childhood.”
The study, published May 10 in Development and Psychopathology, evaluated 306 children at intervals over more than two years, starting when participants were around 3 years old, up to age 5 ½.
Children were from a range of racial, ethnic and socioeconomic backgrounds, with 57% considered lower income or near poverty.
Income was a key marker for adversity.
In addition, the children’s mothers were surveyed about other risk factors that have been linked to poor health and behavior outcomes in children, including family transitions, residential instability, and negative life events such as abuse or the incarceration of a parent.
Against these data, Lengua’s team tested children’s executive function skills with a series of activities, and, through saliva samples, a stress-response hormone called diurnal cortisol.
The hormone that “helps us rise to a challenge,” Lengua said, cortisol tends to follow a daily, or diurnal, pattern:
It increases early in the morning, helping us to wake up.
It is highest in the morning — think of it as the energy to face the day — and then starts to fall throughout the day. But the pattern is different among children and adults who face constant stress, Lengua said.
“What we see in individuals experiencing chronic adversity is that their morning levels are quite low and flat through the day, every day.
When someone is faced with high levels of stress all the time, the cortisol response becomes immune, and the system stops responding.
That means they’re not having the cortisol levels they need to be alert and awake and emotionally ready to meet the challenges of the day,” she said.
To assess executive function, researchers chose preschool-friendly activities that measured each child’s ability to follow directions, pay attention and take actions contrary to impulse.
For instance, in a game called “Head-Toes-Knees-Shoulders,” children are told to do the opposite of what a researcher tells them to do — if the researcher says, “touch your head,” the child is supposed to touch their toes.
In another activity, children interact with two puppets — a monkey and a dragon — but are supposed to follow only the instructions given by the monkey.
When children are better at following instructions in these and similar activities, they tend to have better social skills and manage their emotions when stressed.
Children who did well on these tasks also tended to have more typical patterns of diurnal cortisol.
But children who were in families that had lower income and higher adversity tended to have both lower executive function and an atypical diurnal cortisol pattern.
Each of those contributed to more behavior problems and lower social-emotional competence in children when they were about to start kindergarten.
The study shows that not only do low income and adversity affect children’s adjustment, but they also impact these self-regulation systems that then add to children’s adjustment problems.
“Taken all together, it’s like a snowball effect, with adverse effects adding together,” Lengua said.
Income was a key marker for adversity. In addition, the children’s mothers were surveyed about other risk factors that have been linked to poor health and behavior outcomes in children, including family transitions, residential instability, and negative life events such as abuse or the incarceration of a parent. The image is in the public domain.
While past research has pointed to the effects of adversity on executive function, and to the specific relationship between cortisol and executive function, this new study shows the additive effects over time, Lengua said.
“Executive function is an indicator that shows the functioning of cognitive regulation. Cortisol is the neuroendocrine response, an automatic response, and the two consistently emerge as being related to each other and impacting behavior in children,” she said.
The research could be used to inform parenting programs, early childhood and school-based interventions, Lengua said.
Safe, stable environments and communities, and positive, nurturing parenting practices support child development, while a focus on relationships and healthy behaviors in preschool settings can support children of all backgrounds — those with high as well as low adversity.
In November 2012, the Royal Society of Canada and the Canadian Academy of Health Sciences released an expert panel report on early child development (1). Despite its broad title, the report’s principal focus was the role of early childhood adversity in shaping risks of addiction and mental health problems in adolescence and young adulthood. Key questions that were addressed included:
- Are there identifiable adverse childhood experiences, such as abuse, neglect, chronic poverty, family dysfunction, chronic illness, family addiction and/or mental illness, that lead to poor mental health and unhealthy behaviours, such as addiction, in the adolescent and young adult?
- Is there evidence that the effects of these experiences are due to changes in brain structure and function?
- What is the evidence for the effectiveness of the interventions used to mitigate the effects of adverse childhood experiences on the developing child?
As a coeditor of the report, I believe that its most significant achievement was outlining a new, emerging science of human development that integrates genetics, epigenetics, neuroscience, life course epidemiology and developmental psychology to suggest how early experience can become biologically embedded; thus, fundamentally altering our understanding of how environment and biology jointly influence health and well-being over the life course. Here, I describe nine findings that warrant attention from Canadian paediatricians, family physicians, nurses and other health professionals caring for young children. Collectively, they should transform our understanding of, and attitudes toward, the nature and significance of adverse experiences in early childhood, and influence policy and practice in relation to them.
- Early childhood is a sensitive period in human development (2), during which the brain, especially the circuitry governing emotion, attention, self-control and stress, is shaped by the interplay of the child’s genes and experiences. As children grow, the biological and environmental factors that determine their development become increasingly intertwined. Thus, early adversity and later developmental health are linked through the structural and functional development of specific brain and nervous system circuits, from executive function to responses to stress.
- Extended longitudinal research provides evidence that children who, early in life, contend with chronic adversities, such as family poverty, inappropriate care and child maltreatment are more likely to experience a broad range of impairments later in life (3). These difficulties range from emotional, behavioural, interpersonal, school- and stress-related adjustment problems to more severe difficulties, such as mental health problems, delinquency and criminal offending.
- Developmental trajectories appear early in life (3) and tend to be subsequently reinforced through a cascade of differential exposures to stressful and risky social contexts. There is no single path from early adversity to poor social, emotional, cognitive and mental health outcomes. Moreover, the effects of early adversity are moderated by a wide range of factors, from genes to community-level social support. Beyond parenting, broader factors – at the level of the extended family (eg, grandparents, aunts), community and society – also play an important developmental role.
- Adverse childhood experiences that influence children’s development do not only include dramatic events that are departures from social norms; the day-to-day interactions in children’s lives are much more important than we had previously understood (3). It is the chronic, daily exposure to maltreatment, poor parenting and other adversities, rather than an individual dramatic occurrence of abuse, which causes the most damage to developmental health across our society.
- Although exposure to early adversity is a significant predictor of later problems, they are not inevitable for all children (2). Rather, children vary tremendously in their response to adverse childhood experiences. Early childhood is a sensitive period when children may be more susceptible to both negative and positive experiences. Some children appear to be more biologically susceptible to social context than others and, thus, more predisposed to react to both stressful and nurturing environments. Most importantly, there is reason to believe that these children may also experience the most gains from intervention.
- Early in life, the environment talks to genes and the genes listen (2). Brain development processes are, in part, governed by complex gene-environment interactions that affect the expression of genes. By gene-environment interaction, we mean that (multiple) genes convey a general susceptibility that may result in a negative outcome depending on the child’s experience of environmental stressors. Our genes do not determine our traits; rather, there is a dynamic interplay between nature (genes) and nurture (environment). Recent advances in epigenetics now provide us with mechanisms that may explain how this occurs. Brain development is molded, in part, through changes in gene expression, embedding early experience in human biology, which leads to individual differences in developmental trajectories.
- Parenting begets parenting (4). Individuals exposed to adverse childhood experiences tend to be less equipped to take on a parenting role when they are adults and, in the context of adverse circumstances and the absence of some form of social support and/or intervention, they are more likely to adopt inappropriate parenting behaviours and perpetuate a cycle of negative and adverse parenting across generations. The biological systems and pathways linking adverse childhood experiences to biology and behaviour also extend to the regulation of parenting behaviours, which implies that there is a disruption of the usual behavioural and physiological processes involved in normal parenting, including stress regulation. However, despite the probabilistic associations between early adversity and later emotional and parenting problems, most parents who experienced extreme adversity, such as physical abuse, when they were children will not adopt the same pattern with their child.
- There is now a limited but promising body of research suggesting that child maltreatment and its associated outcomes can be reduced if targeted, intensive and sustained services are deployed (5). Targeting works best when implemented before a pattern of maltreatment has been established, not afterwards. The success of intense, sustained prevention programs targeting high-risk families at birth and early childhood emphasizes that these times are high-priority windows for intervention. Yet, despite all we now know about the importance of the early years, we still tend to ignore the experiences that occur early in the life course and only react when things go dramatically wrong during the teenage years and young adulthood (6).
- In contrast, there is a paucity of credible research evidence examining how broader interventions at the level of childcare, school and community might influence adverse childhood experiences in ways that, in turn, would influence long-term developmental outcomes (5). In some respects, the problem is methodological. When engaging in intervention at the group level, each group (ie, each childcare centre, school or community) is an ‘n of one’ regardless of the number of children involved. Thus, the ability to recruit study groups with a sufficient sample size to conduct a randomized controlled trial with sufficient statistical power is usually beyond the resources of both investigators and granting agencies. Second, and most importantly, is the fact that responses to group-based interventions are very often mediated by the unique social dynamics within each specific intervention group. Because of this, community interventions rarely produce a statistically powerful main effect. Instead, intervention tends to increase the variability in outcomes across intervention groups becasue some groups successfully engage with the intervention and use it effectively, while others do not. Using traditional analytical techniques such an outcome will be deemed ‘negative’ or ‘weak’ because, on average, the intervention groups will show minimal improvement compared with controls. Yet, thanks to economic, sociological and political science research, we now have insight into these sources of variation. Based on the findings from wide-ranging studies of community variation (eg, why Aboriginal teen suicide and Aboriginal employment levels vary hugely from band to band; why seniors die during heat waves in some neighbourhoods and not others; why some watershed communities maintain sustainable agriculture over a millennium while others do not; why the United States biogenetic technology industry is now concentrated in only three places, compared with thirty areas a few decades ago) there is now a strong evidentiary base revealing common underlying characteristics of groups, at the nongovernmental level, that successfully address these challenges. There are ways to evaluate group level interventions using this knowledge base, such as multistage implementation approaches. In broad terms: step one involves an introduction of the intervention to all selected communities; step two evaluates the variability in implementation integrity across groups; step three attempts to teach low implementation integrity communities the techniques that made high integrity communities successful; step four evaluates the effects of step three and identifies communities where implementation integrity remains low; step five proposes alternate approaches for these communities; and step six evaluates outcomes, using dose-response analyses, where ‘dose’ is based on implementation integrity.
Funding: The study was funded by the National Institute of Child Health and Human Development. Co-authors were Stephanie Thompson, Erika Ruberry and Melanie Klein of the UW Department of Psychology; Lyndsey Moran of the Boston Child Study Center; Maureen Zalewski of the University of Oregon; and Cara Kiff of UCLA.
University of Washington
Kim Eckart – University of Washington
The image is in the public domain.
Original Research: Open access
“Pathways from early adversity to later adjustment: Tests of the additive and bidirectional effects of executive control and diurnal cortisol in early childhood”. Liliana Lengua et al.
Development and Psychopathology. doi:10.1017/S0954579419000373