How Brain Development and Trauma are Linked
Science tells us that the foundations of sound mental health are built early in life. Early experiences—including children’s relationships with parents, caregivers, relatives, teachers, and peers—interact with genes to shape the architecture of the developing brain. Disruptions in this developmental process can impair a child’s capacities for learning and relating to others, with lifelong implications. 
Adverse Childhood Experiences (ACEs) are negative, stressful, traumatizing events that occur before the age of 18 and confer health risk across the lifespan. The 10 best studied ACEs are divided into the umbrellas of abuse, neglect, and household dysfunction. These experiences create toxic stress. Children with ongoing, unmitigated toxic stress develop patterns of maladaptive behaviours and physiological disruptions that compromise health over the lifespan. 
FACTS AND STATS
- Before the age of 18, 27.2% experienced abuse and 49.1% experienced family dysfunction.
- Adverse Childhood Experiences (ACEs) rarely occur in isolation. Having one ACE increases the probability of experiencing another one by 84%.
- Children who experienced more ACEs were more likely to be diagnosed with mental health conditions or substance dependence in adulthood.
- Children who experienced more ACEs were more likely to perceive their physical health, emotional health, and social support as poor.
- The association between ACEs and poor health remained strong even when other risk factors for poor adult health outcomes, such as poverty, were taken into consideration.
- Children who experienced both abuse and family dysfunction had the highest risk for negative health outcomes in adulthood. 
Why is It Important?
Toxic stress, which is the result of strong, frequent, and/or prolonged biological responses to adversity, can damage the architecture of the developing brain and increase the likelihood of significant mental health problems that may emerge either quickly or years later. Because of its enduring effects on brain development and other organ systems, toxic stress can impair school readiness, academic achievement, and both physical and mental health in children and, later, adults. Life circumstances associated with family stress, such as persistent poverty, threatening neighborhoods, and very poor child care conditions elevate the risk of serious mental health problems. Young children who experience recurrent abuse or chronic neglect, domestic violence, or parental mental health or substance abuse problems are particularly vulnerable.
Some individuals demonstrate remarkable capacities to overcome the severe challenges of early, persistent maltreatment, trauma, and emotional harm, yet there are limits to the ability of young children to recover psychologically from such adversity. Even when children have been removed from traumatizing circumstances and placed in exceptionally nurturing homes, developmental improvements are often accompanied by continuing problems in self-regulation, emotional adaptability, relating to others, and self-understanding. When children overcome these burdens, they have typically been the beneficiaries of exceptional efforts on the part of supportive adults. These findings underscore the importance of prevention and timely intervention in circumstances that put young children at serious psychological risk. 
What Does It Look Like?
Complex trauma can adversely affect children in a multitude of ways:
- Attachment and Relationships – difficulty developing strong healthy attachment and relationships
- Physical Health – development of chronic or recurrent physical complaints, such as headaches or stomach aches. Adults with histories of trauma in childhood have been shown to have more chronic physical conditions and problems
- Emotional Responses – difficulty calming down when upset, feeling overwhelmed, intense emotional responses to triggers
- Dissociation – mentally separate themselves from the experience as a defense mechanism. Dissociation can affect a child’s ability to be fully present in activities of daily life and can significantly fracture a child’s sense of time and continuity
- Behaviour – difficulty with self-regulation, impulse control, may appear unpredictable, oppositional, volatile, and extreme or overcontrolled, rigid and unusually compliant with adults.
- Cognition – problems thinking clearly, reasoning, or problem solving. show deficits in language development and abstract reasoning skills thus affecting academic success.