What's Psychoneuroimmunology?

Do you know what psychoneuroimmunology is? Here, you'll learn how the immune and nervous systems are related, what topics this discipline investigates, and where they're heading.

Psychoneuroimmunology is the scientific field that studies the interaction between the brain, the endocrine and immune systems, and their pathologies. Among its focuses of interest is the relationship between behavior and the progression of immunological diseases, as well as the evaluations of the role of immune factors in central nervous system pathologies.

The term psychoneuroimmunology was coined in the 1970s by psychologist Robert Ader and immunologist Nicholas Cohen. However, experts also know it as neuroimmunoendocrinology or behavioral immunology.

In itself, it’s a multidisciplinary science that consists of professionals in psychology, psychiatry, immunology, epidemiology, and medicine. Since its goal is to understand the dynamics of human health, it’s an area that has grown rapidly.

The basis of this discipline is that the immune system is regulated by environmental signals through the central nervous system, just as the nervous system receives information through substances secreted by the immune system.

History

Over the centuries, people have devoted a lot of time to studying the relationship between the body and the mind. We can find an example of just how many years these studies go back in the figure of Aristotle. He argued that the psyche and the body act as a single entity, each one reflecting the changes that occur in the other.

Around the 1940s, experts observed how emotions psychosomatically influenced the onset and progression of autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, and hyperthyroidism.

For example, they found that the psychological well-being of relatives with arthritis (who were genetically disposed to the disease) protected them against the condition.

Later, in 1981, scientists discovered a network of nerves that explained the interaction between the nervous and immune systems. That same year, Ader, Cohen, and Felten published the book Psychoneuroimmunology, in which they explained in detail the interaction between the two systems. Shortly afterward, in 1985, they founded the Scientific Foundation of Psychoneuroimmunology.

Main findings

There are several lines of research within psychoneuroimmunology. Broadly speaking, we can identify studies that are looking into:

• Lesions in the brain region controlling immunity and innervation of immune organs.
• Psychological traits and states that influence the onset and course of immune resistance diseases.
• The influence of stress on immunity.
• Effects of neurotransmitters and neuropeptides on immunity.
• Behavioral modifications of stress effects on immunity.
• Psychoactive substances on immunity.
• Individual psychological differences with immunity.
• The occurrence of immunological abnormalities in conjunction with mental illness.

Psychological factors

In this line of research, the goal is to determine which emotional or personality aspects are related to autoimmune diseases. For example, factors such as stress, the ability to express emotions, or negative affectivity.

Researchers have observed that positive emotions are associated with a certain immunity to physical illness and with rapid recoveries without any complications. Likewise, personality has also shown that it has an influence. Thus, introverted people have more infections and somatic symptoms, and are more susceptible to severe illness than extroverts.

Other studies have found evidence that an optimistic and self-controlled attitude is related to better mental health. For example, one study found that AIDS and cancer patients with a more positive outlook showed longer life expectancy compared to those who tended to be more realistic.

Stress

This is one of the most powerful lines in psychoneuroimmunology. There’s an enormous amount of work on this topic. However, the results are quite ambiguous.

Stress is associated with major physiological changes. It activates the sympathetic adrenal-medullary system, the hypothalamic-pituitary-adrenocortical axis (HPA), and other endocrine systems. All of them affect the immune system in different ways.

In the case of the HPA axis, cortisol release suppresses the immune system. Due to this mechanism, stress is highly related to autoimmune diseases such as psoriasis or rheumatoid arthritis.

Occurrence with other mental illnesses

Another area of research deals with autoimmune diseases when they occur together with other mental illnesses. For example, there are data that show that depression is related to immunity due to sleep disturbances.

That is, when sleep rhythms are altered, metabolism is also altered, increasing the production of cytokines related to chronic inflammatory diseases. In addition, there’s also an alteration in circadian rhythms related to cortisol and adrenaline, which, as we explained above, have a close association with the immune system.

Researchers have also observed immunological alterations in patients with schizophrenia. In fact, a viral origin of the disease has been a consideration for quite a few years now. This is due to a higher incidence of antibodies and abnormalities in the levels of lymphocytes. However, the results aren’t conclusive.

The future of psychoneuroimmunology

Considering the interaction between the immune system and the nervous system, there may be a complete change in our perspective towards health. We could understand it as the body’s own ability to regulate its physiology and behavior in the face of changes or alterations. Both systems act by reacting to the environment and communicating with each other.

This leads to a different approach to autoimmune diseases, thus maintaining an interdisciplinary and multifactorial perspective.