How stress and trauma change the brain and nervous system

Dr. Martina Melzer, published: 04/25/2023


From my perspective, conditions like ME/CFS, fibromyalgia, irritable bowel syndrome, long Covid, POTS  are the results of chronic stress, trauma, and stressful childhood experiences.

I could write volumes on the subject. I'll try to give a mini-overview here so you understand what I consider to be the most important points. You can find more details under the strategy "knowledge".


I made a little presentation of the content on YouTube:



Or listen on Spotify and Anchor:


What is stress?

There are different definitions, but stress is mainly one thing: very individual.
Typically, you perceive something as stressful that you subjectively cannot manage, that threatens and overwhelms you, over which you have little control and little influence, that you do not understand and whose outcome is uncertain.

Stress arises in response to a stressor and affects you physically, emotionally, mentally, and at the behavioral level. Stressors are typically new, intense, unpredictable, and uncontrollable. I divide them into external and internal stressors. External factors can be related to work, for example, time pressure, high demands, and little room to decide. They can also be of a private nature, such as relationship conflicts, unhealthy lifestyle, many obligations, but also pathogens are stressors. Internal factors include personality traits such as perfectionism or not being able to say no. The most important stress factors are emotional.

Chronic stress makes people ill.

What is trauma?

Trauma is also difficult to define and is something very individual. But trauma researchers say: Trauma is not the event itself, but what it does to you. It splits you off from yourself, your body, your feelings, the world. You no longer feel connected. You're stuck in the past.

The transition between stress and trauma is fluid in my understanding, and what one person finds stressful is traumatic for another.

Traumatic are events like war, emotional, sexual or physical abuse, severe injuries, accidents or natural disasters. But feeling unloved, abandoned and not wanted can also have traumatic consequences.

Adverse childhood experiences play a special role in chronic stress and trauma, as the U.S. ACE study shows. According to this study, traumatic and stressful childhood experiences such as those mentioned above increase the risk of diseases such as cancer, autoimmune diseases, depression, gastrointestinal diseases, migraine, cardiovascular diseases, stroke, diabetes, ME/CFS, fibromyalgia, irritable bowel syndrome, anxiety disorders and an unhealthy lifestyle.

Psychoneuroendocrinoimmunology: What is it?

Chronic stress, trauma and adverse childhood experiences affect your body, mind and brain. They change your brain, psyche, autonomic nervous system, endocrine system, immune system, and cardiovascular system. That's why I like to talk about psycho-neuro-endocrino-immunology, this field of medical research that explains why everything is connected to everything else.

All stimuli and information from your outside and inside world go to specific nerve networks in different regions of your brain. There they are collected and evaluated. The evaluation is primarily: safe or dangerous. Because one of the most important tasks of your brain and nervous system is to protect you, to secure your life. This then triggers a whole internal cascade depending on the evaluation.

The nervous system consists of different parts. But we are interested in the autonomic nervous system. It controls numerous bodily functions and functions largely involuntarily and unconsciously, i.e. autonomously. It consists of the sympathetic and parasympathetic nervous systems, which can be both in a healthy and an unhealthy state. According to the polyvagal theory, the parasympathetic nervous system, also called the vagus nerve, consists of two branches: the evolutionarily older dorsal vagus and the newer ventral vagus. In a healthy state, the dorsal vagus is responsible for rest and digestion, while the ventral vagus is responsible for safety and connectedness. The autonomic nervous system is in close communication with the intestinal nervous system and the nervous system of the heart.

When information is considered safe, the autonomic nervous system remains in rest mode, we are relaxed, digest, feel connected, are socially engaged, and experience pleasant emotions such as joy. The ventral vagus and dorsal vagus in its healthy state are active. Or we are active and creative, but still feel safe. The sympathetic nervous system in its healthy state and the ventral vagus then do that.

If information is evaluated as danger - stress and trauma are danger signals - the sympathetic nervous system jumps into the fight or flight mode, we are tense and feel unpleasant emotions like fear or anger. This is useful in the short term, but unhealthy in the long run. When we are overwhelmed by the situation and no escape is possible from our subjective assessment, the dorsal vagus jumps into its unhealthy state, which puts us into a kind of shutdown mode. Everything is shut down. This is where emotions like shame and sadness occur. It can also be that sympathetic nervous system and dorsal vagus are very active at the same time - this is then this feeling of being wired and tired at the same time. The transitions between the states are fluid.

To set these mechanisms in motion, the nerve fibers of the autonomic nervous system are connected to all internal organs, to the muscles, tissues and cells. In the event of danger, the so-called stress axis jumps into action, through which stress hormones such as adrenaline and noradrenaline, which belong to the autonomic nervous system, and cortisol are released. They trigger the stress response in the body. This is manifested by dilated pupils, faster breathing, increased pulse and blood pressure, and decreased digestion, among others. The immune system is activated or suppressed. The whole thing influences our thinking and feeling.

In other words, every piece of information from our outer world and inner world triggers a whole cascade of reactions in the body and mind, depending on how it is evaluated in the brain. And that's why I also talk about mind-body syndromes with syndromes like ME/CFS or fibromyalgia.


Translated with the help of DeepL


Important: The statements in this text are the result of my research from scientific studies, professional articles, books, courses, education and training as well as my own recovery process. I have done the best possible research, but nevertheless make no claim to accuracy. In science, something is considered a hypothesis until it is clearly proven (or disproven). That is then evidence, a fact. The statements in this text are a combination of hypotheses and facts.

Also, the content on this page is for informational purposes only and is not a substitute for talking to your doctor or other therapist. Please talk to your doctor or therapist before making any decisions about your physical or mental health. Every way into a mind-body syndrome is something individual, and every way out.