Skin and Psych: Using Habit Loop Science to Interrupt the Itch-Scratch Cycle, With Judson Brewer, MD, PhD

Judson Brewer, MD, described anxiety and the itch-scratch cycle in atopic dermatitis as parallel habit loops, each built from 3 components—a trigger, a behavior, and a reward—that were reinforced through negative reinforcement. In psychodermatology, Brewer said, a stress trigger, such as anticipatory anxiety before a performance, could flare atopic dermatitis (AD) and prompt scratching on the neck or flexural surfaces of the elbows, mirroring how worry reinforced anxiety without resolving it. Brewer said the first step in interrupting either loop was helping patients recognize that they were caught in a cycle, since most had never been taught to see anxiety or itching this way. The second step involved teaching patients to ask, nonjudgmentally, "what am I getting from this behavior?" That question, Brewer explained, generated a negative prediction error in the brain—patients realized worrying or scratching did not deliver the relief expected—which reduced the behavior's perceived reward value and, over time, patients' motivation to repeat it.

Brewer cited clinical data supporting this mechanism: "In one clinical study we did with people with generalized anxiety disorder, we got a 67% reduction in these clinically validated anxiety measures as compared to only a 14% reduction in people who were doing standard clinical care."¹ Rather than emphasizing the word "mindfulness," which he said patients found abstract, Brewer said his Going Beyond Anxiety program taught curiosity and awareness directly, framing worry and itch as urges that could be observed rather than immediately acted on. He said, "Instead of being controlled by our emotions, instead of being controlled by that urge to do something, we learn that that urge comes and goes on its own without us having to do something to make it go away." Brewer recommended a nightly or morning body scan practice to help patients reconnect with bodily sensations earlier in the flare cycle, alongside self-compassion practices, since patients often distanced themselves from bodies that felt unreliable. He added that stress and AD were closely linked clinically, and that helping patients distinguish psychological from physical triggers could address the root cause of flares rather than only their symptoms.²

Dr Delgado is a nurse practitioner specializing in surgical, medical, and aesthetic dermatology. She also founded her private practice, Sunrise NPPA Derm.

Dr Brewer is a psychiatrist and neuroscientist known for his work on mindfulness, anxiety, and habit formation.

References

1. Roy A, Hoge EA, Abrante P, et al. Clinical efficacy and psychological mechanisms of an app-based digital therapeutic for generalized anxiety disorder: randomized controlled trial. J Med Internet Res. 2021;23(12):e26987.

2. Steinhoff M, Yosipovitch G, Canchy L, et al. Breaking the itch-scratch cycle: an integrative approach for atopic dermatitis. Dermatitis. 2025.