Brain–skin connection: The contemporary perspective through neuroendocrinology

This review summarizes the novel and precious data on the direct effects of ancient neuroendocrinologic molecules on the skin and hair and additionally the active production of these hormones by resident skin cells. The data are extracted from PubMed using the keywords neuroendocrinology, hormones, skin, hair follicle, pituitary, hypothalamus, thyroid, and prolactin. The most important neuroendocrinologic axis is composed of corticotropin-releasing hormone, adrenocorticotropic hormone, and cortisol (CRH–ACTH–cortisol) and is related to stress. The CRH–ACTH–cortisol axis is demonstrated to be fully functional in the skin. This review furthermore points out to a possible neuroendocrinologic mechanism likely to explain the association between psychological stress and skin and hair diseases.