Breaking the Itch–Scratch Cycle: An Integrative Approach for Atopic Dermatitis
Martin Steinhoff, Gil Yosipovitch, Ludivine Canchy, Bárbara Roque Ferreira, Claudia Aguirre, Therdpong Tempark, Roberto Takaoka, L. Misery
Abstract
Atopic dermatitis (AD) is a chronic inflammatory skin disease with a significant psychological impact. The cardinal symptom of all phenotypes and severities is chronic pruritus with repetitive itching and scratching due to a vicious itch-scratch cycle that can be worsened or triggered by stress. Neuroimaging of brain areas responsible for itch processing in healthy subjects versus patients with AD has provided insights into the brain circuits involved in itch central perception. In patients with AD, the dorsolateral prefrontal cortex appears to be overactive while regulating the itch-scratch circuit, and this persistent hyperactivation over time may disrupt this brain region. Common mechanisms between addiction and scratching could explain why some patients with AD continue to scratch despite showing clinical improvements from conventional treatments. In addition, molecular knowledge indicates bidirectional neuroimmune circuits between the peripheral nervous and immune system and dysregulated skin cells may aggravate and perpetuate AD severity. We provide an overview of the basic mechanisms that underlie the itch-scratch cycle in AD, especially neural sensitization of nonhistaminergic itch-specific pathways, and discuss how integrative therapies may interfere with central and peripheral mechanisms of chronic itch to reduce neuroinflammation and break the itch-scratch cycle. The connection between mind and body in the itch-scratch cycle, involving central mechanisms, suggests that integrative and multidisciplinary treatment approaches could be helpful as an adjunct to pharmacological treatment in the clinical management of AD. Integrative therapies may potentially help to reduce pruritus and scratching, psychological stress and sleep disturbances, and improve immune and skin barrier dysregulation, AD outcomes, and patient well-being.