What is Toxic Stress


We are sponsoring a free lecture on Toxic Stress on Thursday, October 16th.  Because this is such an important issue, I wanted to give you a little bit of information about what Toxic Stress is, how it differs from a normal stress response, and why it matters.

What is Toxic Stress?

Toxic Stress is defined as a strong, persistent activation of the body’s stress response. It happens as a result of a child being exposed to repeated or unrelenting threats (as seen from the infant or child’s point of view) in their environment which activates their fight, flight, or freeze response.

Neglect, exposure to domestic violence, physical or sexual abuse are just a few of the situations which can trigger this bodily response. In the last newsletter we discussed how the stress response returns to normal as the parasympathetic nervous system kicks in.  Because of the constant or extremely threatening nature of the dangers in the environment, the child’s stress response does not return to normal but is permanently set on “high alert” mode.

While we have known that chronic or extreme stress can cause an abnormal stress response for some time, we have not had direct evidence about the deleterious impact of this type of stress response in infants and young children.  A group of scientists at the Harvard Center for Child Development, including psychiatrist Jack Schonkoff, were interested in studying the impact of this type of stress response in young children.

They coined the term, “Toxic Stress” and theorized that a protective environment buffers the impact of toxic stress.  They have been actively studying the phenomenon.  They have developed some ingenious methods of studying the impact of toxic stress on infants, toddlers, and preschool children through a study of children in orphanages or foster care settings in Bucharest, Romania. They succeeded in constructing a situation where they could randomly assign children to a foster care setting (previously non-existent or extremely rare in Bucharest) or the orphanage (care-as-usual) setting. They then studied children’s brain development (using various brain scanning techniques) and other outcomes after different periods of time in these settings.  The extent of brain differences in these children is truly stunning.

Here are just a few:

If child was taken out of the institution before 24 months of age there was a good chance of a child developing a secure attachment but after 24 months, the chance of developing a secure attachment fell below 30%. After 30 months it was just slightly over 20%

IQ scores are lower in children raised in the orphanage but the score rebounds if taken out of the institution before the age of 24 months

  • Less overall brain electrical activity brain (Marshall, P.J., Fox, N.A. et.al 2004; DeBellis, M.D. 2005)
  • Differences in neural reactions to stimuli like facial expressions or understanding emotions EEG study  (Parker, S.W., Nelson, C.A., et.al. 2005)
  • MRI studies show less volume in PFC, hippocampus, medial temporal lobe, corpus callosum
  • Poorer connectivity between brain areas that integrate complex information (Eluvathingal, T , et. al 2006)
  • This results in Difficulties with learning
  • Difficulties with emotion regulation

So what is the good news?

We now have very specific information that it is the quality of the relationship between a child and their caregiver that builds brain growth.  We also know that a caring, responsive relationship in which a parent actively talks with their child and responds sensitively to a child’s cues is key to forming these strong neural networks that buffer toxic stress.

Interested in learning more? Here are some links and references:

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