The local environment and early experiences shape and develop our children’s brains in deeper ways than we can imagine.
By the time children start school, they’re social little creatures who are developing relationships separate from their immediate family. They have their own friends, temperament, likes and dislikes. They can tell stories, create art and are ready to learn to read, spell and do simple maths. Their capacity to think, problem solve, interact with others, show empathy and even develop a theory of mind (their awareness of others’ states of mind) is emerging.
Children don’t learn these skills in isolation. Every neural process, every thought, feeling and behaviour they develop, is embedded in and influenced by the world around them. Interaction with people, places and things is an absolute requirement for healthy brain development.
Children learn best by play. They’re driven by a natural urge to play, do, taste, explore, feel, smell, experiment and interact—with people and animals, pots and pans in the bottom drawer, and puddles of rain. It’s by interacting so intensely with the world that their brains develop.
Young brains are primed to learn and grow by experience, and the requirement for experience to refine synapses and develop skills is unconditional. Our large, complex, social brains require a long experience-rich childhood to develop. It has been said our extended childhoods enable our brains to better match the rich experiences and diverse environments we humans inhabit. A long childhood is also the foundation of our mind and sense of self—those amorphous mental attributes that make each of us the devastatingly charming, adaptable and distinctive individuals we are.
“It’s possible we’ve underestimated the importance of childhood,” says Professor Richie Poulton, head of the Dunedin Study, a research program that has closely tracked every aspect of the lives of 1037 people born in Dunedin, New Zealand, in 1972 and 1973.
Early life experiences shape developing brain architecture and strongly affect whether children grow up to be healthy, productive members of society. During early childhood, enhanced brain plasticity is a double-edged sword: increased opportunity for learning is paired with increased vulnerability to deprivation and stress. Toxic stress is defined as stress that is extreme or long lasting or occurs outside an environment of supportive, attached caregiver relationships. Toxic stress derails brain development, with damaging effects on learning, behaviour, and physical and mental health across the lifespan.
This vulnerability is clearly demonstrated by the Dunedin Study. Professor Richie has been able to predict with reasonable accuracy which children will grow up with social or health problems.
Growing up in a socioeconomically deprived family, exposure to maltreatment, low IQ and poor self-control are proven predictors of poor adult health and social outcomes, including criminal convictions, prescription fills, welfare claims and hospital visits. This “high cost” group of adults could be reliably identified by three years of age. Rather than blaming the victim for economic burden following on from childhood disadvantage, Professor Richie suggests we focus on early-years intervention or what he calls “grey-matter infrastructure” so we can lift health and social wellbeing as disadvantaged children grow up.
Another group of children living a few hours north of Dunedin has given us additional insights into how extreme stress in infancy impacts social, emotional and cognitive development in childhood.
Starting in September 2010, my hometown of Christchurch was hit by a series of massive earthquakes. The most devastating was on February 22, 2011, when 185 people died and 6600 people were injured. Everyone, including my family, was deeply affected. Over the next two years there were 14,000 aftershocks, including 32 earthquakes over magnitude five. People called living with continual shaking, damaged infrastructure, insurance battles and unrelenting psychological stress “the new normal”.
In the past few years I’ve started hearing stories of Christchurch schools struggling with large numbers of children starting school with learning difficulties and behavioural problems. For example, I knew of one class of 22 children that required four extra learning support teachers. There was a general consensus among my friends and family that this was the impact of children growing up in “the new normal”.
Researcher Kathleen Liberty, an associate professor of child development at the University of Canterbury, is following the lives of a cohort of Christchurch children, who she calls her “post-EQ children”. In New Zealand, children begin school on the day of or near to their fifth birthday, and Kathleen has been gathering data on the social, emotional and cognitive development of these new entrants since 2006. After the earthquakes she has been able to revisit the same primary schools and gather data on post-EQ children, then compare them to the “old normal” baseline.
. . . parents, in particular the mother, are to blame for how resilient or stressed children are.
Kathleen confirms there are significantly more behavioural problems and post-traumatic stress symptoms in the children who started school after experiencing the earthquakes. In her 2016 paper, published in PLOS Natural Disasters, she reports that 21 per cent of post-EQ children showed six or more post-traumatic symptoms such as being withdrawn, clingy, irritable, defiant, unhappy or having sudden mood changes (six or more symptoms is highly indicative of post-traumatic stress disorder, PTSD, in children). Less than nine per cent of pre-EQ children showed as many symptoms.
One of the strongest predictors of whether children would experience difficulties was the age the child was when the earthquakes began. Surprisingly, children younger than two when the sequence began were more vulnerable than older children. But Kathleen suggests this is because the older children experienced a buffer period of normal stress-free brain development. She guesses older children possessed the behaviours, language and cognitive skills to communicate with parents and perhaps make some sense of what was happening when the room was shaking, people were screaming and the world was literally falling down around them.
Because earthquakes strike without warning, the post-EQ boys and girls have grown up in an unpredictable world, many in highly stressed families. During a period of incredible neural plasticity, the children’s stress response systems were activated thousands of times. Exposure to extreme stress before the age of two activates the immature stress response system, including the hypothalamus-pituitary-adrenal (HPA) axis and brain regions that regulate its activity, with enduring consequences for children’s behaviour.
You may be wondering if there were gender differences in how children reacted to the quakes. Kathleen told me that gender differences weren’t detected. Primary-school-age boys and girls were equally affected by growing up with earthquake stress. However, a study of 525 Christchurch teenagers six months after the earthquakes reported clear gender differences in the development of PTSD. Only 13 per cent of boys showed clinically significant PTSD symptoms compared to 34 per cent of teenage girls. This finding is consistent with other disaster zone research and PTSD research in general that finds higher prevalence of PTSD amongst post-pubertal girls and women compared to boys and men.
Intriguingly, one of the buffers against distress was being part of a Maori community. Other researchers have also found the social connectedness, spiritual support and collective dynamics associated within the indigenous community contributed to the resilience of the Maori children in Christchurch.
Kathleen tells me she is now working with schools and families to help children learn to regulate and understand their own emotions and to build resilience. One myth she is working hard to dispel is that parents, in particular the mother, are to blame for how resilient or stressed children are.
“Children are not having problems because of how mum reacts during an earthquake,” she says. “Mothers don’t cause the problems, the earthquakes did. But parents are in a unique position to teach their children how to manage their stress response.”