Childhood Depression and the Brain: HPA axis and Cortisol

The brains of depressed children are different than the brains of non-depressed children.  Depression and anxiety can strain a young, gentle and weary mind but it can also strain a sturdy, rock solid mind.  Depression doesn’t discriminate.   

In my last post I talked about neurotransmitters.  In this post I will write about the HPA axis and cortisol.  I’m trying to write about the brain in a way that most people can understand so I don’t want you to be scared away by some of the complicated names.

Depression and anxiety are about feeling negative emotions too deeply.  These emotions include sadness, despair, hopelessness and fear.  Stress can bring out these negative emotions and these negative emotions can cause stress.

When a person feels stress something called the HPA axis is activated.  It’s not really about what it’s called but what it does.  The H stands for the hypothalamus which is a region in the brain.  Stress causes the hypothalamus to release CRH hormones which stand for corticotrophin-releasing hormone. Again it’s not about their names but what they do. 

This CRH hormone sends a message to the pituitary gland which is also in the brain.  The pituitary gland is the P in HPA axis.  It releases ACTH which stands for adrenocorticotropic hormone.  It sounds complicated but it’s not.  Just know that ACTH is released into the blood stream. 

The A in HPA axis stands for the adrenal glands which are situated right above the kidneys.  When the adrenal glands detect ACTH in the blood they secrete something called cortisol.

Cortisol has been called the stress hormone.  It is released during the fight or flight response through the HPA axis.  Some people naturally secrete more cortisol than others but excessive, chronic stress can cause too much cortisol to be released and over a period of time the cortisol can kill neurons and can inhibit new neurons from forming in certain parts of the brain.  That means fewer neurotransmitters are released. 

I wrote about neurons and neurotransmitters in my previous post.  I’ll write more about the different parts of the brain cortisol can affect in my next few posts but I want to get back to the HPA axis.

In normal brains the HPA axis is a negative feedback loop which just means that when cortisol is released it is supposed to suppress the hypothalamus from releasing CRH hormones.  This is supposed to bring cortisol levels back to normal but in depressed and anxious children this negative feedback loop doesn’t work the way it is supposed too. 

Depressed and anxious children who are under chronic stress from things like trauma, poverty or emotional issues, to name a few, have been shown to have a more hyperactive HPA axis causing higher levels of cortisol. 

Cortisol interacts with neurotransmitters like serotonin, norepinephrine and dopamine.  It also interacts with their neurons and receptors.  Remember from my previous post receptors are the locks and neurotransmitters are the keys.  If cortisol kills off some of the neurons and receptors, then the neurotransmitters can’t do their job which is to help us feel better.  This can cause depression and anxiety. 

Chronic stress and hyperactivity of the HPA axis leading to too much cortisol can cause structural changes in some parts of the brain.  It can be hard to tell if these changes in the brain are genetic or if they are caused by the high cortisol levels. 

In my next post I’ll write about the parts of the brain called the hippocampus and prefrontal cortex.  I hope my posts have helped people understand childhood depression and anxiety a little better.  I welcome comments.  I just ask that you be respectful.  Thanks so much.