After the holiday break I resume my serie about the brain and depression. The topic of today is stress. I’ll try to answer the question how stress occurs in the body and what consequences are possible when something doesn’t work out as intended. There is an interesting link to depression possible.
Stressful life events.
Life has its ways and in one form or another we all do encounter stressful events in our life. That can be all kinds of things, a divorce, an illness, the death of a loved one, losing your job, violence, abuse. Although stress plays a big role in developing a mood disorder, not everyone who is faced with life’s challenges experience one. In fact, most people don’t.
In my previous post I explained how your genes play a role in how sensitive you are to stressful life events. The combination of your genes, your brain and stressful life events can result in depression.
In this post I’m going to talk about stress and its own physiological consequences. Stress triggers a chain of chemical reactions and responses in the body. Our bodies are designed to cope with a certain intensity and amount of stress. When stress is short-lived, we recuperate ‘as normal’. When stress becomes chronic or the system gets stuck in overdrive, long lasting consequences can occur in body and brain.
How stress affects the body.
Stress is an automatic physical reaction to a stimulus that forces you to adapt to change. You notice something and you need to adapt to that. This stimulus can be internal (feeling pain for example) or external (something appears to fall on your head for instance). Every real or perceived danger triggers a cascade of stress hormones that produce physiological changes. You know when you panic! You can notice your stress response in your heartbeat going faster, your breathing becomes more shallow, your muscles tense, your focus diminishes and maybe you sweat a little or a lot.
The stress response starts in your brain, more precisely in the hypothalamus. Together with the pituitary glands and the adrenal glands the hypothalamus forms the HPA-axis. The H(ypothalamus)-P(ituitary)-A(drenal) – axis plays a role in different hormonal changes in the body and it also plays a role in depression.
What does happen in our body when a threat is perceived?
The hypothalamus will release a corticotropine releasing hormone (CRH) that stimulates your body. Hormones travel through your body to organs and groups of cells to deliver a certain message, which in turn will result in a certain response. It’s like a dance or a conversation, action reaction. So from the hypothalamus CRH travels to the pituitary gland where it stimulates the secretion of ATCH (adrenocorticotropic hormone) which goes into your bloodstream to arrive in the adrenal glands. The adrenal glands release cortisol.
Cortisol will make your body and mind ready to fight or flee, but you will react, that is for sure. What are signs that your body is the fight or flight modus?
- your heartbeat goes up, it can be 5 times faster than normal and your blood pressure rises.
- your breath quickens to take in more oxygen to transport to your muscles and vital organs.
- your senses like your hearing and sight become more sharp. You focus on the threat, you get tunnel vision. And your mind also focusses on the threat, you focus.
Remember the hypothalamus that produces CRH that travel into our axis (the pituitary and adrenal glands)? CRH (corticotropine releasing hormone) does other things too. It affects the cerebral cortex, part of the amygdala and the brainstem. It is thought to play a major role in coordinating your thoughts and behaviors, emotional reactions, and involuntary responses. It influences the concentration of neurotransmitters throughout the brain. Disturbances in hormonal systems, therefore, may well affect neurotransmitters, and vice versa.
Now we know what happens to our body under stress, what can possibly go wrong?
As you read the system is quite perfect and that one action leads to another reaction. We fight or flee when necessary and therefore we can protect our life. Normally a feedback loop disables the fight or flight reaction when the threat is gone and the body can recuperate in its normal state.
In some cases the feedback loop doesn’t work as it should and the levels of cortisol (which is responsible for the fight or flight modus) rise too high or just stay too high. This can contribute to problems such as trouble staying asleep, high blood pressure, immune suppression and possibly depression.
Studies have shown that people who are depressed or have dysthymia typically have increased levels of CRH. Antidepressants and electroconvulsive therapy are both known to reduce these high CRH levels. As CRH levels return to normal, depressive symptoms recede.
Research also suggests that trauma during childhood can negatively affect the functioning of CRH and the HPA axis throughout life. Next week I’ll look deeper into the topic of trauma. I hope you enjoyed this installment and I also hope to see you again next week. Any questions, encouragements or remarks are – as always – welcome in the comments.
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