The skin is one of the largest organs in our body, possessing its own immune system and microbiota. Skin balance is regulated by both local and systemic hormones, neurotransmitters, neuropeptides, and cytokines. Therefore, like other organs, the skin can react to stress, and research shows that many dermatological diseases are closely related to the body's exposure to stress and our mental state. How does stress affect the skin? What is psychoneuroimmunology? Which skin diseases are linked to stress? You will find answers to these and other questions in the following article.
Adaptations to Stress
When stress is too intense, it threatens our physical, mental, and social balance, inducing what is known as allostasis—a process stabilizing the internal environment of the body through specific physiological changes (adaptations). Adaptations triggered by stress occur through the interaction of specific organ systems and the substances they release. Firstly, stress activates the hypothalamic-pituitary-adrenal (HPA) axis, releasing cortisol, corticotropin-releasing hormone (CRH), and adrenocorticotropic hormone (ACTH). This leads to various processes preparing our body for stressful situations, such as an increase in blood glucose levels and a decrease in pain sensitivity. Secondly, stress activates the sympathetic nervous system, releasing adrenaline and noradrenaline. This results in increased blood pressure and heart rate, dilation of blood vessels in the heart, lungs, and muscles, and constriction in the intestines and kidneys. Stress can cause both positive adaptations, mobilizing us to act, and negative ones, such as diseases. The individual impact of psychological stress on the body depends primarily on the perception of experienced stressors, which varies among individuals due to differences in genes, experiences, and behaviors.
How Stress Affects Our Skin?
Just like for any organ, stress is not indifferent to the skin. Stress influences our hormonal balance, which is crucial for skin health. Stress mobilizes the immune system, generates chronic inflammation, increases the production of free radicals, potentially accelerating skin aging. Additionally, it diminishes the body's natural antioxidant abilities and accelerates the degradation of matrix components like collagen and elastin. Moreover, stress worsens the functions of the hydrolipidic mantle, increases the activity of sebaceous glands, and intensifies the dilation of blood vessels (teleangiectasia). It's worth noting that the skin contains numerous receptors for neurotransmitters, hormones, and cytokines, regulating its functions and modifying its response to psychological and environmental stressors. Therefore, the skin's reaction to stress is a complex process involving a broad network of immune cells, hormones, and neurotransmitters. The skin is a target for key stress mediators but is also a local source of these factors, forming its own psychoneuroimmunologic connections. The study of these relationships falls within the field known as psychoneuroimmunology.
Psychoneuroimmunology of the Skin
Despite numerous studies on the psychoneuroimmunology of the skin, the exact mechanism by which stress can trigger or exacerbate skin symptoms remains unknown. At the end of the last century, the Neuro-Immuno-Cutaneous-Endocrine (NICE) model was created, encompassing various overlapping mechanisms explaining probable stress-skin relationships. Mechanisms in the NICE model include:
- Dysregulation of the HPA axis and the sympathetic nervous system
- Interaction of various signaling substances within the skin on cells, nerve fibers, blood vessels, and skin glands
- Overproduction of pro-inflammatory cytokines and neuropeptides in the skin and changes in the expression of receptors for these substances
- Development of neurogenic inflammation Chronic stress, in particular, can cause neurogenic inflammation in the skin and simultaneously exacerbate the course of certain skin diseases. Neurogenic inflammation is a form of chronic skin inflammation resulting from the abnormal interaction of immune cells with skin nerve fibers. Numerous neurogenic factors and pro-inflammatory cytokines participate in the entire process. Diseases where neurogenic inflammation plays a role include urticaria, atopic dermatitis, and psoriasis.
Mast Cells and Neurogenic Inflammation
Mast cells play a significant role in the process of neurogenic inflammation and serve as a kind of link between the psychoneuroimmunological axis. Mast cells were described by Dr. Hans Selye, who coined the term "stress," as crucial in recognizing environmental threats (e.g., microorganisms, toxins, physical stress). Mast cells are versatile cells, capable of responding to various local and external factors, and have the ability to release many active substances, making them a unique link in integrating the immune and nervous systems. Mast cells contain 50-200 granules containing various bioactive substances, including biogenic amines (histamine, serotonin), cytokines (IL-1, IL-3, IL-4, IL-6), enzymes (chymase, tryptase), lipid metabolites (leukotrienes, prostaglandins), nitric oxide (NO), heparin, and vascular endothelial growth factor (VEGF). Under the influence of various factors, mast cells can undergo degranulation, the sudden release of granule contents outside the cell. Degranulation can occur due to contact with an allergen but also due to psychological stress. Additionally, mast cells may be located in the vicinity of nerve cells and, by producing serotonin, directly influence the activity of the nervous system. Most communication between mast cells and nerves occurs through the local release of active substances into the intercellular space, such as nerve fibers secreting neuropeptides like substance P.
Psychodermatology – An Interdisciplinary Approach to Skin Diseases
Psychodermatology is a relatively young field that encompasses psychology, psychiatry, and aesthetic medicine, based on the psychosomatic concept describing the inseparable connection between our body and mind. It's worth adding that the psychosomatic connection between the skin and the nervous system also arises from their common embryonic development, as both the skin and nervous system originate from the ectoderm. In Poland, in 2008, the Psychodermatology Section was established within the Polish Dermatological Society. Currently, psychodermatology categorizes skin disorders and diseases related to our psyche and stress into three groups:
- Psycho-physiological disorders, where skin symptoms may appear or worsen under stress, e.g., atopic dermatitis, psoriasis, vitiligo, seborrheic dermatitis.
- Primary psychiatric disorders, where skin changes taking the forefront are a result of mental disorders, e.g., obsessive-compulsive disorders.
- Secondary psychiatric disorders, which are disorders that arise as a consequence of chronic skin changes, e.g., depressive and anxiety disorders. Research has shown that introducing psychiatric treatment in the form of medications or psychotherapeutic methods can have a positive impact on dermatological diseases influenced by stress. Therefore, individuals affected by skin diseases such as atopic dermatitis, psoriasis, vitiligo, and seborrheic dermatitis should consider including methods regulating stress responses in their therapeutic process.
Literature
- Pondeljak N and Lugović-Mihić L. "Stress-induced Interaction of Skin Immune Cells, Hormones, and Neurotransmitters." Clin Ther. 2020 May;42(5):757-770.
- "Psychodermatology. An Interdisciplinary Approach." Publisher: PZWL Warsaw 2023.
- Theoharides T.C. "The Impact of Psychological Stress on Mast Cells." Ann Allergy Asthma Immunol. 2020 Oct; 125(4): 388-392.
- Peters E.M.J. "Stressed Skin? – A Molecular Psychosomatic Update on Stress Causes and Effects in Dermatologic Diseases." J Dtsch Dermatol Ges. 2016 Mar;14(3):233-52; quiz 253.
- Ferensztajn E. and Rybakowski J. "Concept of Allostasis and Neurobiology of Bipolar Affective Disorder." Neuropsychiatry and Neuropsychology 2012; 7, 2: 65–75.
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