Trauma, PTSD, and Chronic Low-Grade Inflammation

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Post-traumatic stress disorder (PTSD) is a complex mental health condition that results from exposure to life-threatening or injurious events. The characteristic symptoms of PTSD include intrusive thoughts, feelings, images, or dreams, avoiding feelings or things that remind you of the trauma, anxiety or anger and bodily signs of tension, and changes in thoughts and/or mood. A subset of people with PTSD experience dissociation—a feeling that they are not present, out of their bodies, or that things are not real.

As we learn more about this disorder, we are finding out that people with PTSD or who have a lot of exposure to trauma also have more chronic medical conditions that those of us who haven't experienced traumas. Researchers have proposed that there is a common mechanism linking the physical and psychological components of PTSD — chronic, low-grade inflammation.

What is inflammation?

Inflammation is a normal reaction of your immune system to harmful bacteria, viruses, or other pathogens. Your immune system sends chemical messengers to the site of the infection in order to fend off whatever is attacking you and return your body to health.

However, in the case of trauma or chronic stress, it seems that your body's stress response system gets dysregulated, resulting in inflammation becoming chronic. Chronic inflammation is a risk factor for many diseases, including cardiovascular, pulmonary, dermatological, and autoimmune conditions, as well as chronic pain.

What's the link between PTSD, stress, inflammation, and disease?

There are many reasons why PTSD could impact your physical health. PTSD may cause you to eat less healthily, or smoke and drink more as a response to stress. It may cause you to act out in angry ways that push other people away, resulting in interpersonal stress and loneliness that are additional risks to health. Another possibility is that PTSD makes your nervous system overreact to the normal stressors you encounter, or puts you in a state of chronic tension and hypervigilance that strains your body over time.

Let's look at how a disrupted stress response system could cause inflammation. Under normal conditions, the sympathetic and parasympathetic branches of your nervous system help you get activated to deal with a stressor by producing epinephrine (adrenaline) or norepinephrine. These chemical messengers generate a "fight or flight" response. Your heart rate speeds up, and breathing gets shallower. When the stressor is over, your parasympathetic nervous system transmits chemical messengers via the vagus nerve to calm everything down again.

You can think of the sympathetic branch as the accelerator and the parasympathetic branch as the brake. If the stressor lasts longer than a few minutes, your HPA (hypothalamic, pituitary, adrenal axis) sends messages to your glands to produce cortisol. Cortisol is a hormone that travels throughout the body, readying your muscles, glands, and organs to deal with a threat. For example, it might tell your liver to produce more glucose that your body and brain could use as fuel. Cortisol release is self-regulating. When there is sufficient circulating cortisol, your body sends a message back to your pituitary and adrenal glands to stop producing more.

Under normal conditions when there isn't a trauma present, this system works well to help you deal with a threat. The sympathetic nervous system helps activate you and the parasympathetic nervous system calms you down again when the stressor is over. Just enough cortisol is released to help activate your muscles and glands and then allow them to go back to a less activated state when the stressor is over.

However, if you have PTSD, the intensity of the trauma or your body's reactions to it seems to disrupt the workings of this system. As a result, the parasympathetic nervous system under-reacts and doesn't put the brakes on, leaving you in a hyper-activated, sympathetically dominant state.

PTSD also seems to interfere with the normal feedback loop regulating cortisol. Because cortisol communicates with the immune system, this can create a situation where inflammation gets out of control. Your immune system keeps producing substances called inflammatory cytokines that are designed to attack pathogens. These cytokines seem to stick around, even when there is no pathogen present, putting your immune system in a state of overdrive.

What does the research find?

A review of research studies linking inflammation to PTSD found evidence of chronic inflammation in people with PTSD, compared to controls (either people not exposed to trauma or people exposed to trauma but who did not get PTSD). Chronic, low-grade inflammation was measured by immune markers, pro-inflammatory cytokines, and white blood cells (specifically, the cytokines C-Reactive Protein, IL-6, TNF-α, and IFN-γ, T lymphocytes and natural killer (NK) cells. Elevated inflammatory markers are known risk factors for cardiovascular, metabolic, musculoskeletal, dermatological, and pulmonary diseases. These diseases are also known to be elevated in people with PTSD. Chronic inflammation has also been linked to depression, and people with PTSD have high rates of co-morbid depression as well.

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Although more work needs to be done, current research supports the idea that PTSD is a reaction to trauma that has long-lasting effects on the way our bodies deal with and recover from stress and on our long-term immunity.