How childhood trauma impacts our brains, bodies – and even our genes

Childhood is the most sensitive period for neurodevelopment, but sadly, it can be disrupted in many ways, from abuse or neglect to exposure to war and violence. Understanding the neurobiological effects of childhood adversity can help us understand and treat its long-term psychological effects. Evidence suggests that these particularly affect the main stress regulation system, known as the hypothalamic-pituitary-adrenal axis. 

The activity of this system can be measured through hormones such as cortisol, collectively known as glucocorticoids. In normal amounts, cortisol helps to mobilise the body to deal with threats or challenges. However, excessive amounts can be harmful – children exposed to war have elevated levels of both cortisol and immunoglobulin-A in their saliva, which also indicates high immune system activity.

The imprints of adversity in the brain can also be more localised. One of the areas most sensitive to the effects of stress is the hippocampus, a crucial structure in the formation of memories and spatial orientation, among other functions. This sensitivity is due to its high concentration of glucocorticoid receptors, the “stress hormones” which are present in high levels in families exposed to war.

The largest and most recent study on the subject reported a 17% reduction in hippocampus size among children exposed to three or more traumatic events compared to those who had suffered none.

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