The role of psychoneuroimmunology in the pathogenesis of psoriasis.

Although it is well known that stress can trigger and exacerbate psoriasis, the exact mechanism is unknown. An explanation is presented based on recent findings in psychoneuroimmunology. The number of cutaneous sensory nerves known to release neuropeptides, such as substance P, is increased in patients with psoriasis. Preliminary data indicate altered concentrations in psoriatic lesions of the same neuropeptides known to be altered in the brain during stress. An anatomical pathway is suggested to explain how descending information from the brain could cause release of neuropeptides in the skin, which would then induce psoriasis. Biochemical and clinical evidence is presented to support the relationship between stress and psoriasis.