When our stress response system becomes activated too frequently or our body loses the ability to shut down the Hypothalamic Pituitary Axis and Sympatho-adrenomedullary axes, our negative feedback inhibition becomes severely disrupted.1 This causes the system to continuously secrete cortisol as if a tiger was standing right in front of you. There are essentially three different types of stress responses: positive stress response, tolerable stress response and toxic stress response.2

A positive stress response is a normal part of life, this is characterized by a mild increase in heart rate and a transient elevation in serum cortisol. Starting your first day of kindergarten might produce this type of response. A tolerable stress response activates the stress systems to a greater degree as a result of a more severe, longer-lasting adversity.2 A good example of this would be the stress experienced during a natural disaster or losing a loved one. On the contrary, a toxic stress response can occur when a child experiences frequent and/or prolonged adversity such as physical or sexual abuse, neglect, exposure to violence, and caregiver substance abuse.1

This prolonged activation of our fight or flight systems leads to a disruption in the normal development of our brain architecture and organ systems which increases our risk for stress-related diseases and cognitive impairments into adulthood.2  Our immune systems are affected, our hormonal systems are affected, even the way our DNA is read and transcribed is affected by this toxic stress response. Brain scans and salivary cortisol levels of kids with multiple traumatic experiences showed smaller volumes of their hippocampus as well as chronically elevated cortisol levels.2

This abnormal response to stress that occurred in childhood as a result of trauma can have disastrous impact into adulthood. People who are exposed to these extremely stressful events are at an increased risk for anxiety, depression, PTSD, major depression, panic disorders, and substance abuse disorders compared to those who have not experienced traumatic events.


  1.     Bremner J. D. (2006). Traumatic stress: effects on the brain. Dialogues in clinical neuroscience, 8(4), 445–461.
  2.     Lanius, R., Vermetten, E., & Pain, C. (2011). The impact of early life trauma on health and disease. Cambridge: Cambridge University Press.