The skin is the largest visible organ of the human body. It is not only the barrier between the body and the external environment, but also an important organ for receiving information from the outside world. In psychophysiology, the functions of the skin are: sensory function, defense function, emotion receiving function, and emotion expressing function. It is easy to understand that the stimulation of natural and social environment not only causes skin physiological changes and skin disorders, but also psycho-psychological changes can cause skin disorders and affect the process of certain skin diseases.
1.Psychosomatic and skin immunity
Regarding the mechanism of psycho-psychological factors affecting skin immune function, it is mostly believed that it is related to the change of corticosteroid level in the body. After mental stimulation, the level of steroid hormones and the number of lymphocytes in the blood are increased by tens of times, and the degree of both increases is proportional to the degree of stimulation. Studies using steroid hormone synthesis inhibitors and steroid hormone receptor activators have shown that steroid hormones regulate the amount and distribution of leukocytes by binding to adrenal steroid hormone type II receptors.
In addition, acute mental stimulation increases the expression of skin interferon a, IL-1a and TNF-a mRNA. The reduced skin response to allergens due to prolonged mental stimulation may be related to dysregulated corticosteroid metabolism and reduced production of epidermal IL-1a and TNF-a during allergen-induced dermatitis. When the organism is in a good mental state, its skin response to allergens is reduced. When watching humorous comedy programs, the sensitivity of the skin to dust mites and pollen was significantly reduced; while watching boring programs about weather and so on, the sensitivity of the skin to allergens was not changed.
2.The effect of mental and psychological stimulation on the proliferation and differentiation of epidermal keratin-forming cells
If the animal free activity is restricted at the same time, 48 hours of continuous light and sound stimulation, the animal epidermal proliferation is inhibited, the expression of keratinocyte differentiation protein is also reduced; cold plus restrict the animal free activity only 12 hours, the animal epidermal DNA synthesis rate is significantly reduced. After restricting the animals to free range for 6 hours per day for 4 days, the epidermis thinned, except for a 32.1% increase in blood corticosteroid levels and a 63% decrease in testosterone levels; antiproliferative cell nuclei (PCNA) staining showed a significant decrease in the number of PCNA-positive cells.
After animals lived in solitude for 2-30 days, it was found that the rate of epidermal cell DNA synthesis was lower the longer they lived in solitude, whether in the basal state or in dermatitis. Since corticosteroids have an inhibitory effect on epidermal proliferation, while testosterone has a promoting effect on epidermal proliferation, and corticosteroid receptor blockers can correct the skin changes caused by mental factors, therefore, the elevation of corticosteroids and the decrease of testosterone caused by mental factors may be one of the reasons for the inhibition of epidermal proliferation.
3.The effect of psycho-psychological stimulation on the barrier function of epidermis
Psychological stimulation increases the level of corticosteroids in blood, which reduces the synthesis of epidermal lipids and the formation of lamellar bodies, thus delaying the recovery of skin barrier function. Psycho-psychological factors have different effects on epidermal permeability barrier function, and different parts of the skin respond differently to psychological stimuli.
Interviews significantly enhanced the basal barrier function of facial skin, but had no effect on the basal barrier function of forearm skin; reducing sleep time and exercise had no effect on the basal barrier function of both facial and forearm skin. However, both the interview and the reduction of sleep time significantly delayed the recovery rate of the skin barrier function of forearm.
4. Psychosomatic factors and skin diseases
The skin and the nervous system are developmentally co-derived from the embryonic ectoderm, and they share several hormones, neurotransmitters and receptors, which determines that there are multiform and intrinsic organic links between the psyche and the skin at macro and micro levels. Psychological burden or stress can affect the function of the central nervous system, and a series of adaptive responses occur in the nervous system, endocrine system, and immune system, which are regulated by the hypothalamic-pituitary-adrenal (H-P-A) axis, triggering the upregulation of a series of stress hormones, including corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and glucocorticoids;
It is also accompanied by the release and activation of other stress response mediators (substance P, nerve growth factor, calcitonin gene-related peptide, vasoactive intestinal peptide, norepinephrine and acetylcholine), forming a local stress response system, which not only causes autonomic dysfunction, but also affects the secretion of skin sweat glands, microvascular diastolic function, skin and hair nutrient function, and can lead to Various skin diseases occur.
4.1 Eczema dermatitis-type skin diseases.
Psychosomatic stimuli may induce atopic dermatitis. Studies have shown that patients with atopic dermatitis experience more psychological stimuli than the general population before the onset of the disease. The incidence of atopic dermatitis (AD) was significantly higher in children younger than 4 years of age whose parents were divorced or separated (32.3%); the incidence in those whose parents were not divorced or separated was only 21.2%. the condition of AD fluctuates with the mental state of the patient.
Itching of the skin increased when AD patients were in a poor mental state (e.g., anxiety, irritability, depression, etc.). Mental stimulation (including playing computer, playing fighting games, sitting on the roadside in heavy traffic, and frequent ringing of telephone) can significantly aggravate the localized skin reaction induced by dust mites and pollen in AD patients compared to non-AD patients. The levels of substance P, IgE, IL-4 and IL-10 in the blood were significantly elevated.
Nerve growth factor (NGF) stimulates the release of histamine from human mast cells, and its expression and plasma levels are significantly increased in AD lesions, which effectively confirms the involvement of NGF in the pathogenesis of AD by affecting the release of histamine. They also found that the peripheral blood levels of AD patients were significantly higher and were associated with the degree of AD activity.
They also found that peripheral blood erythrophil NGF levels were significantly increased in AD patients, which stimulated inflammatory processes and local tissue damage, thereby inducing the development of AD. In contrast, Toyoda measured NGF and SP in serum of AD patients by enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay, respectively, and found that both were higher than normal controls, and their concentrations were positively correlated with the severity of the disease. It is hypothesized that NGF and SP play an important role in the pathogenesis of AD, and that they may affect the immune response of patients by interacting with the target cells of the immune system.
4.2 Vitiligo.
Psychological status plays an important role in inducing vitiligo, and mental stress can induce the development of the disease. Although vitiligo does not make the patient painful and the patient’s activities are not restricted, vitiligo greatly affects the patient’s quality of life, many patients feel distressed and anxious, self-image is greatly reduced, leading to a decline in self-confidence and social isolation, especially facial vitiligo patients are more prone to anger and disillusionment, and immature patients also experience irritability and depression in a bad mood.
Vitiligo is often thought to be the result of autoimmune deficiency. The metabolites of catecholamines and 5-hydroxytryptamine directly affect pigment loss. Psychologists have long known that anxiety and depression lead to impairment of the patient’s autoimmune and endocrine system. 5-hydroxytryptamine has a very important role in depression and its associated symptoms, thus vitiligo is associated with depression and anxiety.
The reduced density and number of low affinity nerve growth factor receptors on nerve fibers or nerve cells in vitiligo patients suggest that the release of nerve growth factor from peripheral nerves causes nerve growth factor receptors to be overexpressed on melanocytes, which may lead to damage of melanocytes.
4.3 Psoriasis.
Psychological stress can cause or exacerbate the symptoms of psoriasis. When compared to patients with many other skin diseases, psoriasis is more susceptible to psychological stressors than other skin diseases. The emotional response caused by mental stress is processed by the limbic system of the brain and causes hormonal changes in the hypothalamus that regulate endocrine secretion. In the skin tissue, substance P (SP) and nerve growth factor (NGF) act together to influence the dynamic epidermal homeostatic processes.
The nerve growth factor (NGF) promotes nerve growth, causes upregulation of SP and CGRP expression, activates T cells and induces inflammatory cell infiltration, promotes keratinocyte proliferation, and forms the characteristic histological features of psoriasis.Farber et al. suggested that neuropeptide, especially SP-induced neurogenic inflammation, is a factor in the pathogenesis of psoriasis based on clinical observations and some laboratory studies. The release of SP can lead to mast cell degranulation and vasodilation, causing histopathological changes in the skin of psoriasis.
4.4 Alopecia areata and alopecia areata.
The disease is associated with mild neuroendocrine disorders, and is also a dermatological condition clearly influenced by emotions. Onset is often due to mental shock or severe anxiety. The mechanism of the influence of mental factors on the onset and condition of baldness is not fully understood, and substance P seems to be involved. After animals were mentally stimulated (24 hours a day with sound at a frequency of 300 Hz for 7 days), apoptosis of hair follicle keratin-forming cells was significantly increased and proliferation was inhibited.
The hair growth cycle of the stimulated animals was altered (early entry into the regression phase) and accompanied by the onset of perifollicular inflammation. At this time, there was an increase in dermal substance P-positive nerve fibers. The same results were obtained after 2 days of systemic administration of substance P alone. substance P receptor antagonists inhibited the above-mentioned changes induced by psychological stimulation and systemic administration of substance P.
4.5 Systemic lupus erythematosus (SLE).
Psychological factors influence the development of certain autoimmune diseases such as SLE, and different scholars have studied the relationship between the two and reached similar conclusions. the severity of physical impairment in SLE patients is significantly correlated with the patients’ extreme depressive state, and severe short-term negative life events are directly responsible for its appearance. prolactin (PRL), gonadotropin-releasing hormone, melatonin, and many other hormones are present in SLE patients abnormalities.
PRL has been well studied and is associated with disease activity and severity. In vitro PRL promotes IgG production by individual nucleated cells, and the induced IgG is significantly associated with disease activity. They found that SP, calcitonin gene-related peptide (CGRP), and neuropeptide Y (NPY) were present in large amounts in the kidneys of lupus mice.
Except for NPY, neuropeptide concentrations were extensively reduced in the lymphoid-like organs of mice. Meanwhile, neuropeptide levels in the mouse brain were abnormal. The changes in their learning memory function paralleled the reduction of NPY, SP, and CGRP in the hippocampus. Also, the expression of NPY and vasoactive intestinal peptide (VIP) was reduced in the hypothalamus.
4.6 Urticaria.
Clinically, there are many types of urticaria with complex triggers. Urticaria can be triggered by a change in spirit or mood due to an earthquake or watching a soccer game. Some patients develop urticaria every time they are mentally stimulated. A survey of 75 patients with chronic allergic urticaria found that the lives of patients with urticaria were more significantly disturbed by mental and emotional disturbances in the 6 months prior to the onset of the disease compared to controls.
The degree of itching of the skin was directly proportional to the degree of mental depression of the patients. Urticaria induced by mental factors may be associated with adrenaline, and local intradermal injection of adrenaline or norepinephrine to these patients may induce urticaria; beta-adrenergic receptor blockers may prevent its occurrence. In addition, local adrenocorticotropin-releasing hormone increases in the skin after mental stimulation, and the latter promotes vasodilation and increases the permeability of the blood vessel wall.
4.7 Acne vulgaris.
Mental stimulation is often both a trigger and an aggravating factor for its onset. Marital breakups and student final exams can aggravate the condition, and the severity of the condition is directly proportional to the degree of mental tension. Treatment of acne with antidepressant drugs can achieve good results. The mechanism by which mental factors affect acne is not clear. Although the severity of acne is related to the amount of sebum, no effect of mental stress on the amount of sebum has been found.
4.8 Other.
Medium-wave UV light is more likely to induce skin cancer in mentally stimulated animals. Skin cancers occur early, are numerous, progress quickly and fade slowly. One clinical survey showed that 46% of patients with cutaneous melanoma had been subjected to significant mental stimulation (such as divorce, bankruptcy and unemployment) within 5 years prior to the onset of the disease. Treatment of malignant melanoma supplemented with psychiatric therapy is effective in improving survival and reducing recurrence rates.
Restriction of free movement of animals reduces herpes simplex virus-specific CD8+ T cells; reduces interferon gamma production; and accelerates replication of viral DNA. This may be the reason why people are susceptible to herpes simplex when they are mentally shocked. In addition, mental stimulation delays the healing of skin trauma, decreases the expression of epidermal antimicrobial polypeptides, and increases the severity of skin infections.
Psychological factors can regulate the biological functions of the skin and influence the onset and progression of dermatological diseases. The skin disease itself can affect the mental state of the patient and even the surrounding people, and maintaining a good mental state can help prevent the occurrence of skin diseases. In the treatment of dermatological diseases, complementary psychotherapy can improve the efficacy. Therefore, mental factors are an important part of the diagnosis and treatment of skin diseases that cannot be ignored.