Communication between the brain and the immune system takes place, among other things, via hormones such as the stress hormone cortisol. Defense cells also produce messenger substances known as interleukins: they control the activity of the immune system and – if they are present in large quantities in the blood – signal to the brain that, for example, an infection is raging in the body. The brain then raises the body temperature and makes the patient feel weak and listless – so that he or she takes it easy. If the brain registers that the interleukin level and thus the activity of the immune system is too massive, it shuts down the body’s defenses again.
In addition to such messenger substances, the autonomic nervous system also serves as a communication medium, sending messages from the body to the brain and vice versa.
Alarmed immune cells
Chronic stress weakens the immune system
Chronic stress, on the other hand, has a different effect: The cortisol level in the blood is then permanently elevated. The stress hormone attaches to receptors located on the surface of certain white blood cells. As a result, these cells secrete less interleukin-1-beta. This messenger substance normally stimulates immune cells to multiply. Interleukin-1-beta also increases the activity of natural killer cells and promotes the formation of antibodies that specialize in certain pathogens. If the level of this messenger substance drops, the effectiveness of the immune system also decreases.
Anyone who is constantly “under power” should not be surprised if he is repeatedly paralyzed by an infection. In stressful times, many people also experience a recurrence of the annoying herpes blisters, whose causative agents are normally kept in check by the immune system. Wounds also heal more slowly when the injured person is stressed.
Sport as a stress brake
Anything that counteracts stress, on the other hand, strengthens the immune system. Sport, for example, causes cortisol levels in the blood to drop. Regular physical activity thus strengthens the immune system.
Targeted relaxation techniques, such as autogenic training, progressive muscle relaxation or mindfulness exercises, therefore also support the body’s defenses.
The fatal power of negative emotions
Negative emotions also have a negative effect on the immune system. People who suffer from depression or anxiety are therefore more susceptible to infections. The extent of this influence is shown, among other things, by studies with cancer patients. In one study, for example, half of the breast cancer patients who also suffered from depression died within five years – but only a quarter of those cancer patients who were not depressed.
The reason for this could be that mentally stable patients have more natural killer cells in their blood. In addition to pathogens, these can also track down and destroy degenerate cells.
Positive energy boost
Positive emotions, on the other hand, can strengthen the immune system and even improve the chances of recovery from cancer. Psycho-oncology therefore aims to counteract the psychological stresses associated with cancer. As part of the treatment, behavioral therapy techniques are used to strengthen positive thoughts and defuse negative thoughts. Visualization techniques are also used to create a positive mood.
Hyperactive immune cells
This is probably due to a lack of cortisol, experts believe. Cortisol normally inhibits the production of interleukin-2, but when cortisol levels are low, interleukin-2 production increases. This calls more T cells into action, which also attack the body’s own cells in the context of autoimmune diseases. This theory is supported, among other things, by observations that in some pregnant women with rheumatoid arthritis the symptoms suddenly disappear – during pregnancy the cortisol level rises.
Allergy boost due to stress
A similar mechanism means that the symptoms of allergic diseases can worsen under stress. This can happen, for example, with neurodermatitis and asthma. The immune system of those affected is overstimulated and produces larger quantities of immunoglobulin E. These antibodies attach themselves to the skin during allergic reactions. In allergy patients, these antibodies attach themselves to the so-called mast cells (a subgroup of leukocytes), which then release histamine. This substance causes the typical allergy symptoms such as itching, reddening of the skin and swelling of the tissue (edema).
Learning a relaxation exercise can therefore also make life easier for allergy sufferers, as studies have shown: Asthma sufferers suffer attacks less frequently, the skin of neurodermatitis patients improves, and hay fever sufferers also benefit from targeted relaxation.
