Effects of Childhood Trauma on the HPA Axis

Over two-thirds of children experiences at least one traumatic event before the age of 16. Childhood trauma is much more common and relevant than we may expect. SAMHSA (the Substance Use and Mental Health Services Administration), describes psychological, physical, or sexual abuse, community or school violence, national disasters or terrorism, sexual exploitation, neglect, and many more as examples of childhood traumatic events. Traumatic events in childhood have been linked to susceptibility to adult psychological and psychiatric conditions, and the main culprit is in dysregulation of the HPA (hypothalamic-pituitary-adrenal) axis.

A traumatic event negatively impacts the stress response system by inducing hyperarousal of the sympathetic nervous system. Hyperarousal of the stress response can cause physiological changes like increased blood pressure, heart rate, and respiration, changes to perceiving the environment, and outward behaviors like crying/shouting. The difference is that these behaviors tend to be advantageous to the stress response in adults, while they tend to be maladaptive in children because children lack the ability to readily protect themselves physically. There is also a notable difference between the normal stress response and one to a traumatic event, which is that following a traumatic event, the state of hyperarousal continues long after the trauma, causing disruptions in the HPA axis, limbic system, and prefrontal cortex. A child’s brain is very sensitive and susceptible to endocrine changes during a time of development, so it is crucial to consider the downstream effects of childhood trauma.

The HPA axis is accepted as the major neuroendocrine stress response system which helps an organism adapt in stressful times. During activation of the SNS, the hypothalamus first releases of corticotropin-releasing hormone (CRH) to increase alertness. Then, release of CRH signals to the pituitary to release adrenocorticotropic hormone (ACTH), which signals to the adrenal glands to release cortisol which helps the body adapt to stress. Stressors, either physical or nonphysical, lead to a temporary spike in cortisol which causes system dysregulation. Also, activation of the amygdala (which processes fear-inducing stimuli) causes an overproduction of CRH.

Overall, stressful situations in childhood effectively cause dysregulations of the HPA axis which lead into adulthood. It has been shown that children who experienced trauma like violence or abuse have dysregulated cortisol levels before they even reach adulthood. This is an important consideration because there are assumed links between cortisol dysregulation and adult psychiatric disorders such as major depressive disorder (MDD), PTSD, bipolar disorder, and psychosis.

‌Murphy, F., Nasa, A., Cullinane, D., Raajakesary, K., Gazzaz, A., Sooknarine, V., Haines, M., Roman, E., Kelly, L., O’Neill, A., Cannon, M. & Roddy, D.W. (2022). Childhood trauma, the HPA axis and psychiatric illnesses: A targeted literature synthesis. Frontiers in Psychiatry, 13(748372), 1-15. https://doi.org/10.3389/fpsyt.2022.748372.

Understanding Child Trauma. (n.d.). Www.samhsa.gov. https://www.samhsa.gov/child-trauma/understanding-child-trauma#:~:text=Child%20trauma%20occurs%20more%20than.