It’s all connected

What happens in the young brain has a big impact on the body – and long-term health. Monica Crouch explores how early childhood teachers come into the picture.

A working paper released in 2020 by the Center on the Developing Child at Harvard University in the United States reveals, at granular level, how young children who experience poverty, violence or threats of violence, poor nutrition, housing instability and systemic racism are primed for chronic physical and mental health issues as adults.

The paper, Connecting the brain to the rest of the body: Early childhood development and lifelong health are deeply intertwined, spells out what early childhood teachers have long known or strongly intuited: that when teachers are properly paid and staff-student ratios are manageable, there is lower staff turnover.

Low staff turnover in turn fosters stability. And stability fosters stronger, more supportive and responsive relationships between children and their teachers, leading not only to greater professional satisfaction for teachers, but also a far better chance of good physical and mental health for children as they progress into adulthood.

Adversity impacts health

“The extreme challenges of 2020 have laid bare longstanding inequities that affect the lives of children and families, as well as the health of a nation,” Jack P Shonkoff, Professor of Child Health and Development at Harvard said.

“Significant adversity in the lives of young children can disrupt the development of the brain and other biological systems. And these disruptions can undermine young children’s opportunities to achieve their full potential.”

But it’s not just reaching potential that’s compromised, it’s a child’s long-term health. Cardiovascular diseases, diabetes, respiratory illnesses, obesity, addictions, anxiety and depression all have their roots in early childhood.

In releasing the paper, Professor Shonkoff drew attention to two key points: what happens in early childhood has a big impact on short-term and long-term outcomes in learning, behaviour and both physical and mental health; and all of this is interconnected and learning potential is strongly linked to physical and mental health. This, he said, means that when young children experience good primary health services and their families have a liveable income it affects both learning and health. Equally, early education and care also affect both learning and health.

Poor health outcomes are more likely if we do not adequately support children experiencing persistent hardships or threats.

All systems go

You may remember the old song that goes something like “your leg bone’s connected to your knee bone, your knee bone’s connected to your thigh bone, your thigh bone’s connected to your hip bone …”. So is every system within our bodies – brain and nerves, heart and lungs, gut and digestion, energy production, fighting infection, hormones and physical growth – they’re all interconnected.

The white paper likens these systems to “a team of highly skilled athletes” – each system ‘reads’ its environment and responds to it, and shares information with the other systems.

When young children experience strong, responsive relationships with parents and teachers, their biological systems ‘read’ this and lay down solid foundations not only for social and emotional development, school readiness and future learning but also for a lifetime of sound physical and mental health. Unfortunately, when these relationships and supportive experiences are lacking, the reverse is also true.

Relentless stress

If a child’s stress responses are activated frequently and intensively during early childhood, the child can become permanently set on high alert. “If the world is a dangerous place, the internal systems designed to protect us need to develop in a way that anticipates frequent threats,” Professor Shonkoff said.

Children who experience domestic violence or threats are particularly at risk. So are children in the grips of poverty, racism, unsupportive caregiving, overcrowding and excessive noise. Those who are less active because they lack safe playing spaces are prone to all these issues in their adult years.

A fearful or stressed child produces excessive amounts of the primary stress hormones, adrenaline and cortisol. These hormones are useful in a fight or flight situation: they increase the heart rate, elevate blood pressure and boost energy supply. At the same time, they temporarily suppress the immune and digestive systems. Once a threat has passed, all levels return to normal.

But if threats and fear are ever present, long-term activation of the stress response and overexposure to these hormones can lead to anxiety and depression, digestive problems and weight gain, sleep disturbances, diabetes, heart disease and immune disorders.

On the mental health side of the ledger, constantly elevated stress levels in early childhood can lead to problems with emotional regulation and memory, addictions, anxiety and depression.

“Poor health outcomes are not inevitable, but they are more likely if we do not adequately support children experiencing persistent hardships or threats, particularly in the face of structural inequities that impose enormous challenges,” Professor Shonkoff said.

Again, their teachers and centres can provide stability and a safe haven.

Shifting gear

Investing in early childhood education and care not only affects learning outcomes, it also positively influences children’s long-term health. Good outcomes are easier to achieve with early intervention – it is far harder to rebuild faulty foundations in later life.

Investment in young children and the teachers who educate them is vital. When teachers are properly valued and supported, they are more inclined to reciprocate that support in their workplace, providing stability for children. When access to essential resources and these supportive relationships is secure, a child’s building blocks of resilience and wellness are strengthened.

“The time has arrived for a mindset shift for the early childhood field as part of a broader movement for social change,” Professor Shonkoff said. “The brain is indeed connected to the rest of the body, but health and education are separated in policy.”

An integrated approach that involves the expertise of early childhood teachers is essential to mapping a way forward for the early childhood education and care sector, for young children and, by extension, society as a whole.

Six key lessons from the Harvard report
  • All biological systems interact with each other and the environment.
  • Early childhood experiences impact physical and mental health in adulthood.
  • Childhood adversity is associated with heart disease, diabetes and obesity.Poverty, homelessness and violence are often precursors to depressive disorders.
  • Supportive relationships in stable environments help children build adaptive skills.
  • Returns on science-informed investments in early education and care are clear.


National Scientific Council on the Developing Child (2020), Connecting the Brain to the Rest of the Body: Early Childhood Development and Lifelong Health Are Deeply Intertwined, Working Paper No 15,