Cortisol, T-Rex, and Your Baby

This post is part of the 2010 API Principles of Parenting blog carnival, a series of monthly parenting blog carnivals, hosted by API Speaks. Learn more about attachment parenting by visiting the API website.

The debate centered around “spoiling” a baby vs. cry-it-out (CIO) extinguishing methods normally focuses on parental life style.  Even when framed in an argument that children need to learn to “self-soothe” the primary argument still seems to be that sleeping through the night is the primary goal for the sanity of the parents and the maturity of the child.  (This idea that children need to learn self soothing is very flawed – see Authentic Parenting’s great article Autonomous babies, babied children.)

I’d like to look at this question from a much more objective standpoint – that is how CIO affects the brain of an infant.

Your Baby’s Brain – An Unwired House

At the moment of birth a baby has the most brain cells it will ever have.  Over the next two years the number of brain cells will decrease (and continue to decrease over your lifetime).  The important factor isn’t really the number of neurons but the connections (called synapses).  The interesting thing about connections is that they are shaped by experience and thus are grown after birth through interactions with the world.  (In some of the most depressing research I’ve done – click at your own risk – children deprived of interaction, such as feral children, develop much fewer brain connections and can lose the ability to make connections).  So, even though a newborn has more neurons their brain is not very dense with connections – this is called synaptic density.  

Your baby’s brain is like a house with all the outlets installed but none of the wiring.  Parents, through interacting with children and exposing them to experiences, help wire the brain and teach the brain how to wire – traits that last a lifetime.

Cortisol – Run From the T-Rex!

So how does stress effect the developing brain?  Cortisol gets bad press but it is useful in the human body.  When a dangerous situation happens cortisol alters key things in your body to help you respond (fight or flight) and remember.  However, our bodies were not designed to experience chronic stress.

The stress system in our bodies is really simple.  Yeah right!  Here’s a graphic describing the interplay of brain, hormones, glands, and organs:

Did you get all that?  Yeah, me neither.  The important thing to note is (a) it is a loop – if you look at the circular path in the image (even without understanding the acronyms) you can see that prolonged stress response can increase stress response leading to a cycle of too much cortisol, and (b) it affects almost every system in your body:
  • Cortisol counteracts insulin, contributing to hyperglycemia.
  • Cortisol stimulates gastric acid secretion which increases loss of potassium.  Potassium is essential to neuron function.
  • Cortisol inhibits loss of sodium from small intestines of mammals.
  • Cortisol weakens the immune system. Cortisol prevents proliferation of T-cells by rendering the interleukin-2 producer T-cells unresponsive to interleukin-1 (IL-1)
  • Cortisol lowers bone formation thus favoring development of osteoporosis in the long term.
  • Cortisol reduces calcium absorption in the intestine.
  • Cortisol works with adrenaline to create short-term memories of stressful events.  This is important in reminding cavemen not to taunt the T-rex the next time they are out hunting – hence the beneficial purpose of a short-term stress response.  However, long-term exposure to cortisol results in damage to cells in the hippocampus – your brain’s long-term memory powerhouse. This damage results in impaired learning.”

Non-Responsiveness and Crying

Since cortisol was meant to be a short-lived condition the body reacts to chronically elevated levels by actually destroying synapses.  In response your body produces more cortisol.  Basically, the long-term effect is to wire the whole system for over-reaction so that every cortisol producing event causes your body to over-produce cortisol.  Hence, all the effects above are prolonged.

“By regulating affect, the caregiver is also regulating the release of neurohormones in the infant’s brain. High levels of cortisol, a stress hormone that may well be released in the brain during states of distress, has been shown in some animal studies to destroy synapses (Schore, 1996 emphasis mine).”

This actually structurally changes the child’s brain in a way similar to an adult with prolonged depression

“Stress early in life can alter the development multiple neurotransmitter systems and promote structural and functional alterations in brain regions similar to those seen in adults with depression (Kaufman and Charney, 2001)

Infants that experience persistent crying episodes were 10 times more likely to have ADHD and were also more prone to poor school performance, antisocial behavior, increased aggression, impulsivity, and violence Wolke, Rizzo, and Woods and Perry, B. (1997), “Incubated in Terror: Neurodevelopmental Factors in the Cycle of Violence,” Children in a Violent Society, Guilford Press, New York.)

Responsiveness – The Cortisol Antidote

As much as parents can effect brain development in a negative way they can also do so in a positive way,

“In the inevitable event of distress states in the infant, the caregiver’s moving in to repair the connection and comfort the infant reduces the levels of cortisol and related stress hormones. As a result, the frontal cortex develops a greater concentration of glucocorticoid receptors that can modulate stress responses (Schore, 1996).

You can create a child that handles stress well, is less prone to depression, has a high-degree of emotional intelligence, and is better able to self-soothe as an adult.

The only question you have to ask yourself is – do you want your baby to self-soothe now or when they are an adult?

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Author: Paige

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  1. Thanks for linking to me! Love the article, we need more concrete ones like this to prove to people how CIO is damaging

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  2. Great post. I've been reading all the links. Facinating!

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  3. Excellent points. While I appreciate most of the attached parenting principles, I have tried to talk my wife into letting our son cry a bit more when he's tired. Your post reminded me of things I learned while getting my Neuroscience degree, and the logic was very sound.

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  4. What a great post! I've heard that cortisol can make it harder for a child to fall asleep..then when they finally do, it makes them wake up sooner. Crying increases the levels so it's a horrible cycle. Your research is even better evidence of the real LONGTERM damage you're doing when you CIO. Love this thought: "The only question you have to ask yourself is – do you want your baby to self-soothe now or when they are an adult?"My parents didn't let me CIO, but I grew up in a very stressful environment. I'm hoping that I can avoid that for my daughter…because I do not want her to end up with all the depression issues I've had over the years. Thank you for giving me something to think about!

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  5. Nice summary! It is very important that we inform the public on the possible effects of "crying it out." The reason I say possible is because we don't have the long term data to say with absolute certainty what the effects are. However, I agree that all evidence points to this not being a healthy practice.
    Check out… and
    for more on the developing nervous system as affected by parental responsiveness (or lack of).
    Keep up the great work!

    Post a Reply


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