The job of our immune system is to fight off disease and illness
To understand the impact of stress on our immune system, it is important to understand the way that our immune system works.
Your body makes several types of white blood cells to fight off disease or illness. One of these (produced in our bone marrow), called lymphocytes, circulate in the blood and lymph fluid and help our immune system by making antibodies and other substances that battle cancer and infections and by killing cells that are infected or that are foreign to your body.
Our body has three main lymphocytes:
- B cells (or B lymphocytes), or B cells, make antibodies that help our body fight infections, by attacking bacteria, viruses, and toxins;
- T cells (or T lymphocytes), attack foreign cells, cancer cells, and cells infected with a virus; and
- NK cells (natural killer cells), which contain granules with enzymes, that can kill tumor cells or cells infected with a virus.
All these lymphocytes work together as part of our immune system, where NK cells work with T-cells, to destroy mutant cells and virus infected cells where T-cells are the cells that attack and destroy tumorous cells by releasing cytokines.
Stress causes our immune system to break down, resulting in serious disease
Numerous scientific studies have now firmly proven the link between our body’s stress response, and the healthy functioning of our immune system.
Ground breaking research led by Carnegie Mellon University, found that under chronic stress, the body lost its natural ability to regulate its inflammatory response, which illustrated for the first time how this leads to the development and progression of disease.
Cortisol, we’ve learnt, is one of the stress hormones that is released as part of our body’s stress response, and amongst other things, cortisol acts to regulate and reduce inflammation in the body.
However, elevated levels of cortisol over a long period of time, effects the way our body controls inflammation.
One finding is that it appears that cortisol may actually degrade the disease and illness fighting white blood cells, and so as the number of white blood cells decreases, the efficiency of the immune system decreases, opening us up for illness and disease.
Another finding, is that this long-term exposure to cortisol results in the immune cells in our tissues becoming less sensitive to the hormone, due to changes with the cytokine production within the immune system, and so we suffer from immune dysregulation and chronic inflammation.
It is then this out of control inflammation that in turn, promotes the development and progression of the diseases, that result from the weakened immune system (viruses, infections, cancer) and the autoimmune diseases, such as rheumatoid arthritis, lupus, multiple sclerosis, irritable bowel disease, Graves’ disease and Type 1 diabetes.
A good example of this mechanism, is the Carnegie Mellon University research, which showed that people suffering from psychological stress are more susceptible to developing the symptoms of the common cold.
With the common cold, the symptoms are not caused by the virus; instead, they are the side effects caused by our body’s inflammatory response, in its efforts to fight the infection.
The greater then, our body’s inflammatory response to the cold virus, the greater is the likelihood that we will experience these symptoms of a cold.
What’s more, many retrospective studies into the stress/disease relationship, found that up to 80% of patients reported uncommon psychological stress in the period before onset of the disease.
In addition, studies that specifically investigated the effect of increases in the epinephrine and norepinephrine stress hormones, have reported weaknesses in immune system when elevated levels of these were found in the blood.
While increases in epinephrine and norepinephrine have been observed to promote the release and redistribution of white blood cells, including T-cells and B-cells, these increased stress hormone levels, at the same time, also decreased the efficiency of the T-cells and B-cells.
Increased levels of cortisol, reduces the effectiveness of our disease fighting T-cells
In addition, the corresponding increase in cortisol during chronic stress, also significant impacts the integrity of our immune system.
Beyond this, issues such as have also been attributed and development and progression of cancer.
There is now a known direct link, between the increased cortisol levels and a marked decrease in T-cells, which reduces the ability of the T-cells to locate and destroy mutant and foreign cells, therefore leaving the antigens undisturbed by the T-cells, which may then develop into cancerous tumors.
The effects of acute and chronic stress on B-cells are still under investigation, but it is thought to be similar to those on T-cells.
In further support of the stress-immune system link, is the ongoing research that also suggests that chronic stress decreases NK cell activity through a profound effect on cytokine production.
Our immune system may take a long time to recover, after the stress has gone – although it will recover
Once the chronic stress has passed, depending on both the individual and the length of the stress, our immune system may still take a long time to recover.
Studies that have looked at changes in immune level and disease in population groups following natural disasters such as earthquakes and hurricanes, have found that a compromised immune system has remained for months following the disaster event.
Another study of current and former caregivers of spouses with Alzheimer’s disease, found that the effect of their NK-cells were significantly reduced when compared with a control group and that on average, the reduction of the immune system continued for three years after the role as caregiver ended.