A child's experiences early in life are important building blocks for the developing brain. Genes - nature - are like the blueprint. They provide the basic framework for brain development.
However, genes do not design the brain completely. Environmental influences - nurture - fine tune how the brain works by shaping which brain connections get used. Connections that are used more grow stronger and more permanent, whereas ones that do not get much use fade away.
Together, genes and the environment build the foundation for all future development. Safe, stable and nurturing relationships early in life lead to healthy development. But children's brains capture other experiences as well: stressful events.
However, not all stress is bad. Positive stress involves normal childhood experiences, like starting daycare, or meeting a new person for the first time. This stress is essential for healthy development, because it helps children develop coping skills and confidence.
But when stress is frequent, chronic, and uncontrolled, it is toxic to children, especially when they do not have a caregiver to provide support or buffer the stress. Adverse childhood experiences – ACEs - such as abuse, neglect, exposure to intimate partner violence, parental depression or addiction, and poverty are toxic stressors which could lead to lifelong changes in learning and behavior. ACEs early in development can impact social, emotional, and cognitive functioning, increased risk-taking behaviors such as drinking and substance use, and increased risk of disease, disability, and social problems later in life.
The question is - how do adverse childhood experiences impact a lifelong development. One of the most important systems in our body is our stress system. It's activated when we experience stress.
We become alert, our heart rate increases, and so do our stress hormone levels - cortisol and adrenaline. Our body is ready to react - what is known as fight or flight. A short period of time after the stress is over - or if a child receives support from a caregiver - the stress response turns off and the body returns to a normal state.
Adverse childhood experiences create stress responses that stay active, and without the support of a caregiver, the system has difficulty shutting off completely. This constant and prolonged activation can affect immune system functioning and increase the chances of sickness, infection, and disease. Prolonged activation of stress hormones is also toxic to the brain.
Certain areas of the brain are more vulnerable to toxic stress, including the executive centre, or the brain’s control centre, an area important for solving complex problems, attention, reasoning, impulsivity, inhibition, and learning. A second area is the emotional centre - the brain's alarm system - which is involved in processing and interpreting emotions, and the ability to control impulses. The third area is the memory and learning centre - the brain's filing cabinet - which plays a major role in learning and the formation and retrieval of memories.
Science shows that adverse childhood experiences impact all of these brain centres. Behaviourally, what we begin to see is emotional distress, poor emotion regulation, greater impulsivity, learning difficulties, and physical and mental health problems. More recently, science has begun to look at how ACEs cause changes in gene expression through a process called epigenetics which helps us understand how nature and nurture interact.
Epigenetics causes changes in the way genes work, without changing the DNA code itself. This occurs through chemical changes influencing how the code is used. In other words, genes are like the hardware in a computer: they determine the boundaries of what is possible.
However, we need an operating system to tell the hardware what to do. Epigenetics is like the operating system directing the function of a gene’s DNA hardware. The genes we are born with are the genes that we have for life, but experiences like nutrition, exercise, smoking, stressors, and relationships all affect our biology.
Adverse childhood experiences are associated with epigenetic changes related to stress, brain development, cognition, and systems associated with mental and physical health. Changes that happen early in brain development are more likely to be enduring, and are possibly passed down to future generations as well. The good news is that positive, supportive relationships at any stage in life can make a difference.
However, supporting families and children early on will help prevent many of these negative outcomes. One of the key ingredients for healthy development is having warm, loving, and actively engaged caregivers. This involves promoting serve and return interactions, where caregivers actively and warmly engage with the child: making eye contact, responding to sounds, words, gestures, emotional needs, and sharing experiences like reading and play.
Providing programs that support caregivers to strengthen these abilities are the blocks that build healthy foundations for life.
