Have you ever felt extremely frustrated from trying all the skincare available in the world that docs and skincare junkies swear by without seeing any kind of improvement? Well, maybe you need to wider your perspective and treat your skin health from a psychodermatologically point of view. Psychodermatology is a field that addresses the close relationship between stress and skin conditions. Recent clinical observations link psychological stress to the onset or aggravation of multiple skin diseases. At Uzza Cares we want to talk about the connection between mind and skin and the recent discoveries in the fields of psychology, endocrinology, skin neurobiology, skin inflammation and pharmacology and how a healthy relationship with our skin can have a positive impact on our mental health.
Let’s talk about stress
Psychological stress happens when you are under mental, physical, or emotional pressure. It is perceived by the brain and stress hormones such as corticotropin-releasing hormone (CRH), glucocorticoids, and epinephrine are released. This triggers a wide range of physiological and behaviour changes and responses that try to adapt the body to the stress. However, if the stress responses are inadequate or excess, they may trigger adverse physiological events.
Recent research has confirmed skin both as an immediate stress perceiver and as a target of stress responses. As the largest organ of the body, skin plays important barrier and immune functions, maintaining homeostasis between external environment and internal tissues. It is composed of two major layers: epidermis and dermis. The epidermis is a continuously renewing layer where basal proliferating keratinocytes gradually differentiate, move up and eventually slough off the surface. The outermost layer of the skin epidermis, the stratum corneum (SC), is composed of dead and flattened corneocytes embedded in a matrix of lipids. Corneocytes contain numerous keratin filaments bound to a peripheral cornified envelope composed of cross-linked proteins. While the flattening of the secreted lipids vesicles form intercellular lamellar disks, which then disperse and join together to form multiple, continuous membrane sheets. The dermis is composed of fibroblasts and extracellular matrix which provides elasticity and tensile strength.
Here’s a compilation of the main stress mediators and their roles in skin:
| STRESS MEDIATOR | SOURCE | EFFECTOR CELL | FUNCTIONS IN SKIN |
|---|---|---|---|
| CRH |
Hypothalamus; Skin keratinocytes, sebacytes, and mast cells |
CRH-R1 is expressed in epidermis, dermis and subcutis layer; CRH-R2 is expressed in in hair follicle keratinocytes and papilla fibroblasts |
Stimulation of downstream ACTH and cortisol production; Proliferation, differentiation, apoptosis, inflammation, and angiogenesis. |
| ACTH |
Pituitary gland; Skin melanocytes, epidermal and hair follicle keratinocytes and dermal fibroblasts; Langerhan cells, monocytes, and macrophages |
MC2-R is expressed in skin melanocytes, hair follicles, epidermal keratinocytes, sebaceous and eccrine glands, as well as dermal fibroblasts, sebaceous and eccrine glands, muscle and dermal blood vessels |
Stimulation of cortisol and cortocosterone production; Melanogenesis, cytokine production, cell proliferation, dendritic formation, hair growth, immune and inflammation regulation. |
| Cortisol |
Adrenal cortex; Skin hair follicles, melanocytes, and fibroblasts |
glucocorticoids receptor (GR) is ubiquitous expressed in all skin cells |
Major impact on the immune and inflammation system; Cell proliferation and survival via the PI3K/Akt pathway; Hair follicle proliferation and differentiation; Epidermal barrier formation. |
| Neurotrophins |
Central nervous system; Skin sympathetic neurons, mast cells, T-cells and B-cells, keratinocytes, fibroblasts, and melanocytes |
Two receptors TrK and p75 are expressed in mast cells, immune cells, keratinocytes, fibroblasts and melanocytes |
Promote skin innervations; Promote survival and differentiation of mast cells, and modify inflammatory cytokines expressions; Promote proliferation of keratinocytes; Important for melanocytes migration, viability and differentiation and protect them from oxidative stress and apoptosis; Promote fibroblast differentiation and migration, and possibly contraction and MMP secretion. |
| Substance P | Sensory nerve fibers | Mast cells, macrophages, T-cells |
Cytokine release to induce inflammation, activate mast cells, and induce lymphocyte proliferation Induce vascular permeability. |
| Prolactin |
Pituitary gland; Skin hair follicle and epidermal keratinocytes, fibroblasts, adipocytes, sweat glands, and sebaceous glands |
Prolactin receptor (PRLR) is ubiquitous expressed except in fibroblasts |
Autocrine hair growth modulator by promoting catagen (hair regression); Stimulate keratinocytes growth and keratin production in keratinocytes; Sebum production in sebaceous glands; Immuno-modulation. |
| Catecholamines (epinephrine and norepinephrine) |
Adrenal medulla; Skin nerve fibers, keratinocytes |
adrenergic receptors are expressed by natural killer cells, monocytes, and T cells, keratinocytes and melanocytes |
Regulate keratinocytes proliferation, differentiation, and migration; Promote melanogenesis in melanocytes; Decrease fibroblasts migration and collagen secretion and impair wound healing; Suppress IL-12 in dendritic cells leading to blunted Th1 and increased Th2 differentiation; Important for lymphocyte trafficking, circulation, proliferation, and cytokine production. |
How brain and skin communicate with each other
Skin is the primary sensing organ for external stressors, including heat, cold, pain, and mechanical tension. Three classes of receptors (thermoreceptors for heat and cold, nociceptor for pain and mechanoreceptors for mechanical changes) are responsible for transmitting the outside signals to the spinal cord, and then to the brain. In skin, multiple neuroinflammatory conditions can be triggered or aggravated by stress, such as: psoriasis, atopic dermatitis, acne, contact dermatitis, alopecia areata, itch or Pruritus, and erythema.