Psychoneuroimmunology: How Emotions Influence the Immune System

Guest article by Judith Weinzierl (B.Sc. Psychology) from MentalStark

Psychoneuroimmunology - a rather convoluted word that you may have had to read twice to understand. This relatively new field of research deals with the connection between the psyche and the immune system. This article gives you an overview of how the two complex systems influence each other, how the interplay is being researched and what findings are already worth considering.

What influence does the psyche have on our health?

What is the subject of psychoneuroimmunology?

Psychoneuroimmunology is a relatively new field of research in psychosomatics, the branch of research that deals with the influence of psychological and social factors on the body. Psychoneuroimmunology examines the connections between the nervous system, the immune system, well-being and behavior. The starting point of this research is the finding that there is a close anatomical connection between the sympathetic nervous system and the immune cells in the spleen. Later, hormones and the psyche as well as psychosocial stimuli were added as further influences on the connection between the nervous system and the immune system. The research includes, for example, biological examinations of tissue and blood, studies on the influence of stress, stress processing and personality traits on the function of the immune system and the role of psychological factors in the development of infectious diseases and cancer.

What are the most important psychological factors influencing the immune system?

The answer to this question is, as is often the case, stress. Stress is a term for which there are many different definitions. In general, it refers to the reaction to stress that is experienced as excessive or uncontrollable - depending on a person's individual resilience . The triggers of these reactions, so-called stressors, can be diverse and at the same time unavoidable. Everyone has stressors in their life. These can be short-term or long-term and differ in their intensity of stress. This means that stressors include everyday events such as missing the bus, failing an important exam, and possibly traumatic events such as traffic accidents or sexual assault. The individual level of stress can also vary with long-term stressors. These include, for example, dissatisfaction with the job, persistent unemployment or chronic illnesses. But what influence does the psyche have on the immune system? Here, the distinction between acute stress and chronic, i.e. ongoing, stress is important: Acute, short-term stress, which is triggered in the body even during sporting activity or by an important deadline, ensures that the immune system is activated. Once the stressors have subsided, the stress response is downregulated again and the immune system returns to its original state. This is something that happens every day and our bodies are used to it. However, with ongoing stress, the immune system can no longer regulate itself as well. This can lead to it slipping into a permanent imbalance and, for example, triggering silent inflammation in the body.

Everyone experiences stress differently – one thing is certain: it can make you sick.

What happens on a physiological level in the body?

At the physiological level, a large number of hormones, cells, nerves, organs and brain areas are involved. Accordingly, the physiological processes are very complex. However, the decisive factor is the communication between the central nervous system (CNS) and the immune system. This communication takes place in two ways. Firstly, there are direct nerve pathways to the relevant organs such as the bone marrow, spleen, lymph nodes and skin. Secondly, stress hormones can be systematically released. But what exactly happens? The HPA axis, which consists of the hypothalamus (H), pituitary gland (H) and adrenal gland (N), is of central importance. Now it gets a little complicated: the activation of stressors causes CRH to be formed in the hypothalamus, which in turn activates the release of ACTH in the pituitary gland. ACTH then leads to the activation of glucocorticoids. That's a lot of abbreviations that can be quite confusing. CRH are corticotropin-releasing hormones which, like glucocorticoids, are messengers for regulating metabolism during stress and can in turn influence the cells of the immune system. Glucocorticoids include their best known representative: cortisol. On the one hand, this ensures that glucose is released from the liver. This supplies the body with energy so that it can react to a stressor (in case it is necessary to flee from a saber-toothed tiger). On the other hand, cortisol is important for regulating inflammatory processes by binding to the corresponding receptors. This also prevents the released energy resources from being used up by stimulating the immune system. In summary, this means that the immune system is activated in the event of acute stress and reacts with an inflammatory reaction which is quickly balanced out again. What exactly happens on a physiological level during chronic stress has not yet been sufficiently researched. There are (at least) two possibilities: The HPA can be overstimulated or inhibited. This leads to a change in the stress adaptation mediated by cortisol and the inflammatory processes can no longer be adequately regulated – thus, cortisol loses some of its power over the inflammatory processes.

How does the psyche strengthen the immune system?

In addition to social relationships and well-being, the positive influencing factors include the sense of control, self-efficacy and sleep. The sense of control and self-efficacy are closely related and have been identified as protective factors in studies with people who care for their relatives. The sense of control describes one's own belief that one has control over the difficulties of one's own life and has an important influence on one's own experience of stress. Self-efficacy refers to the expectation of being able to handle new or difficult tasks based on one's own skills. Psychological well-being is in turn closely linked to social relationships. Research shows that positive social relationships, a high level of perceived social integration and the availability of social support have a positive influence on the immune system. In addition, sufficient sleep at night is one of the positive influencing factors on the immune system. Those affected can influence self-efficacy, for example, through psychotherapy, as you can read in our article on behavioral therapy for multiple sclerosis .

Does a weakened immune system affect the psyche?

It is undisputed that an experience of illness can also become a stressor for mental health. It is undoubtedly stressful to be confronted with illness - even to the point of one's own mortality. Added to this are worries about painful, possibly socially restrictive symptom flare-ups. Dealing with the origin of symptoms and clarifying possible diagnoses can also be stressful, as you can read in our article on dealing with the diagnosis of multiple sclerosis . However, not every autoimmune disease is automatically associated with a higher risk of mental stress or disorders. A key term for the connection between a weakened immune system and the psyche is so-called sickness behavior . This includes a combination of experiences and behaviors that occur when a person's immune system is under stress. This stress can be triggered by viral infections, but also by hidden, chronic inflammation. Sickness behavior includes symptoms such as exhaustion or loss of appetite, but also sadness, lack of interest and difficulty concentrating. These symptoms are necessary adaptive reactions of the organism in order to save enough energy to fight the infection. Cytokines are crucial for sickness behavior. These are small proteins that can be released by various body cells in response to activating stimuli. They also transmit information between the cells of the peripheral immune system and the CNS and can trigger inflammation. A study on the treatment of hepatitis C, in which the patients were treated with pro-inflammatory cytokines, showed that 30-50% of the participants developed symptoms such as loss of appetite, depressed mood and/or impaired sleep. Conversely, drugs that inhibit the effect of pro-inflammatory cytokines improve the mood of participants with inflammatory diseases and increase the effect of antidepressants in severe depression. This means that even subliminal, chronic inflammation can put a strain on the psyche without those affected being aware of this connection.

Treatment approaches: Mind and body in harmony

Overall, it can be concluded that inflammation is a universal reaction to physical and psychological stress. The systematic treatment of inflammation is therefore crucial. The current state of research does not yet allow universal recommendations to be made for the treatment of all diseases. However, the studies on sickness behavior in particular show that it is worth listening to your body, taking a break and allowing yourself to rest even when you first feel a slight feeling of illness. This can support the body in its healing process. But it cannot (unfortunately) be concluded that this is sufficient for every mental or physical illness. However, the findings from psychoneuroimmunology offer a broader view of various treatment methods that can be combined to reduce inflammation and improve psychological well-being. In addition to classic pharmacological treatments, nutritional and psychological interventions are also possible. When it comes to nutrition, for example, it is important to note that highly processed foods with refined carbohydrates and additional sugar are associated with higher inflammatory markers. In contrast, interventions that increase the consumption of healthy fats , fruit, and vegetables have a reducing effect on inflammation. Psychoneuroimmunology is a young field of psychosomatics in which a lot of research is still necessary and possible. The aim is to enable holistic treatment of mental illnesses by looking at the immune system and psychological stressors. At the same time, more attention should be paid to psychological influences on somatic illnesses. This will enable new, holistic treatment methods to be developed. However, it is already becoming apparent that there will be no universal solution, but that people must be viewed in all their complexity and individuality. This complexity includes, among other things, individual genetics, intestinal structure, and the individual stressors in a person's life. Research is currently looking, for example, at the connection between early childhood trauma and inflammation. So it remains exciting.

External sources

• Alessi, M.G. & Bennett (2020). Mental health is the health of the whole body: How psychoneuroimmunology & health psychology can inform & improve treatment. J ournal of Evaluation in Clinical Practice , 26, 1539-1547. DOI: 10.1111/jep.13386
• Ehlert, U. & von Känel, R. (eds.) (2011). Psychoendocrinology and psychoimmunology . Berlin Heidelberg: Springer Verlag
• Haase, H. (2015). Psychoneuroimmunology. In: L. Rink, A. Kruse & H.Haase (2015). Immunology for beginners . Berlin Heidelberg: Springer Verlag.
• Hannemann, J., Ott, M., Singer, M., Bliem, H. & Schubert, C. (2017). Psychoneuroimmunology and autoimmune diseases - a paradigmatic challenge. Wissen zkm, 5, 48-55.
• Irwin, MR (2015).Why Sleep Is Important for Health: A Psychoneuroimmunology Perspective. T he Annual Review of Psychology ,66, 143-72. DOI: 10.1146/annurev-psych-010213-115205.
• Kohut, M. (2019). Exercise and psychoneuroimmunology. Current Opinion in Behavioral Sciences Cu, 28, 152-162. DOI: 10.1016/j.cobeha.2019.06.002
• Müller, N. (2017). Psychoneuroimmunological foundations of mental illnesses. In H.-J. Möller, G. Laux & H.-P. Kapfhammer (eds.) Psychiatry, psychosomatics, psychotherapy. Berlin, Heidelberg: Springer Verlag. (From p. 307)
• Pongratz, G. (2021). The stressed immune system and autoimmunity. Current Rheumatology , 48, 258-266. DOI: 10.1055/a-1389-7949
• Schubert, C. (2016). Psychoneuroimmunology, chronic stress and physical illness. Psychotherapy in Dialogue, 1, 16-21. DOI: 10.1055/s-0041-109254
• Schubert, C. & Hannemann, J. (2017). Psychoneuroimmunology and autoimmune diseases – a paradigmatic challenge.
• Straub, RH & Cutolo, M. (2018). Psychoneuroimmunology – developments in stress research. Wien Med Wochenschr, 168, 76-84. DOI: 10.1007/s10354-017-0574-2