Studying the relationships between different biological systems in the body, such as the immune system or the endocrine system, and the brain (and the human mind) is the main objective of a discipline called psychoneuroendocrineimmunology.

This science helps us to understand such important aspects as how psychological factors can influence the evolution or course of an illness, or how stress affects our quality of life.

In this article we explain what psychoneuroendocrineimmunology is and what it studies , and we give you the keys to understand how stress affects our immune system and what impact the mind has on our health.

What is it and what does psychoneuroendocrineimmunology study?

Psychoneuroendocrinimmunology, also known as psychoneuroimmunology, is the discipline that studies the interactions between behavioral, neuronal, endocrine and immunological processes . Researchers know that the nervous system and the immune system can communicate with each other, but it is only relatively recently that we have begun to understand how they do so and what it means for our health.

One of the basic aspects that this discipline assumes is that mind and body are two inseparable entities. It follows that stress affects the body’s ability to resist illness. In addition, we know that the brain influences all kinds of physiological processes that were once thought to be non-centrally regulated.

There are effects of psychological factors in numerous diseases , such as rheumatoid arthritis, diabetes, hypertension, heart disease or inflammatory bowel disease, among others. The goal of psychoneuroendocrine immunology is to study precisely what role the physiological functioning of the neuroimmune system plays in health and disease, as well as the physical, chemical and physiological characteristics of the components of the immune system.

Connections between the brain and the immune system

As the field of psychoneuroendocrine-immunology grows and develops, many discrete pathways of communication between psychological factors and the immune system are discovered.

In recent decades, the depth of integration between the nervous system and the immune system has been slowly decreasing, and one of the key aspects has been to better understand the functioning of the hypothalamic-pituitary-adrenal (HPA) axis and the impact that psychological stress has on this particular system.

The hypothalamic-pituitary-adrenal (HPA) axis

The HPA axis involves three small endocrine glands that secrete hormones directly into the blood . The glands in question are the hypothalamus and pituitary, which are neurological neighbors, and the [adrenal glands](adrenal glands), located on top of the kidneys. This triad of tissues controls reactions to stress and regulates processes such as digestion, the immune system, sexuality, mood, and energy use.

A notable chemical in the work of the HPA axis is corticotropin-releasing hormone (CRH). The hypothalamus releases CRH in response to stress, illness, exercise, blood cortisol, and sleep-wake cycles. It peaks shortly after waking and slowly decreases during the rest of the day.

However, in a stressed individual, cortisol levels rise over long periods of time. During stress, the body believes that it is in imminent danger, so cortisol triggers a series of metabolic changes to ensure that enough energy is available in case it becomes necessary to fight or flee. One of these energy-saving tactics is to suppress the metabolically costly immune system, saving vital glucose for the life-threatening event.

Of course, in modern humans, stress levels can rise for a variety of reasons, and very few of these situations involve a real threat to survival and life. Thus, such ongoing stress can reduce the capabilities of the immune system, with negative consequences for our health.

In contrast, there is evidence that oxytocin, produced during positive social interactions, helps to buffer the activity of the HPA axis. And this has been shown to promote health benefits, such as increasing the speed of wound healing.

Different stress, different immune system

In a discipline such as psychoneuroendocrinimmunology, clinical research is very important . In a meta-analysis of 300 empirical studies it was found that certain types of stress alter different aspects of the immune system. Brief stressors, such as examinations, were compared with chronic stressors, life-changing events, such as caring for a loved one with dementia.

Brief stressors tend to suppress cellular immunity (the type that deals with cellular invaders, such as viruses) while preserving humoral immunity (usually dealing with pathogens outside of cells, such as parasites and bacteria). Chronic stressors, on the other hand, tended to suppress both types of immunity.

Stress has a measurable effect on the strength of the immune system and therefore on its ability to protect us. In a very real way, managing stress levels can help maximize the power of the immune system. Research has shown over and over again that people in stressful situations have measurable changes in physical responses to injury. Whether it’s slowed wound healing, a higher incidence of infection, or a worse prognosis for cancer survival.

For many years, the immune system has been considered an autonomous and independent mechanism, but as we now know, this is not the case. The brain communicates regularly with the cells of the immune system and vice versa , which indicates that stress is both psychological and physical. Therefore, learning to manage stress is an important skill if we want to prevent and reduce the problems associated with many diseases and have our immune system in optimal condition.

The impact of the mind on our health

The effect of psychological factors on our health can be really significant . In a discipline such as psychoneuroendocrinimmunology, we have tried to investigate how the “mind” and cognition influence our immune system and our health in general, and the results can be surprising.

Here are some examples of what we know so far:

1. Psychological grief

Stories of recently deceased people dying shortly after their partners are quite common, and are not usually apocryphal. A recent study that followed more than 90,000 widowed individuals found that during the first week after mourning, mortality was twice the expected rate.

2. The intestine

It is now fairly well established that there is a strong association between sustained stressful life events and the occurrence of symptoms in functional gastrointestinal disorders, inflammatory bowel diseases and the so-called irritable bowel syndrome.

3. Cancer

Although there is no scientific evidence directly linking positive thinking to cancer reduction, health professionals working with patients with this disease are well aware that a patient’s perspective, attitude, and motivation and the amount and quality of psychological support can greatly affect the outcome of their disease.

4. H.I.V. (human immunodeficiency virus)

Research has found significant evidence that high levels of stress and decreased social support accelerate the progression of certain diseases, including H.I.V.

5. Skin problems

We know that conditions such as psoriasis, eczema and asthma are conditioned by psychological aspects. The effect of daily stress can cause a person to have outbreaks or their symptoms to become more severe.

6. Wound healing

The speed at which a surgical patient heals has also been linked to psychological factors. For example, increased levels of fear or distress before surgery have been associated with worse outcomes, including longer hospital stays, more post-operative complications, and higher rates of re-hospitalization.

In addition, in one study of patients with chronic lower leg injuries, those who reported higher levels of depression and anxiety showed significantly delayed healing.

Bibliographic references:

  • Kanba, S. (2001). Psychoneuroimmunology: A Dialogue between the Brain and Immune System. Journal of International Society of Life Information Science, 19(1), 141-145.

  • Pérez de Alejo Rodríguez, L. M., Moré Chang, C. X., González Álvarez, Y., & Alemán Zamora, A. (2019). The Psychoneuroendocrinoimmunology: claim of an integral vision in the medical studies. Edumecentro, 11(3), 254-261.

  • Sivik, T., Byrne, D., Lipsitt, D. R., Christodoulou, G. N., & Dienstfrey, H. (2003). Psycho-Neuro-Endocrine-Immunology (PNEI): A Common Language for the Whole Human Body. Psychotherapy and Psychosomatics, 72(5), 292.