Agreeableness and Self-Consciousness as Predictors of Induced Scratching and Itch in Patients with Psoriasis.

Background: Psoriasis (PS) is a frequent skin disease accompanied by itch, a symptom that has been shown to be related to depression and self-consciousness. PS patients describe themselves as more agreeable than healthy controls (HC), a trait that might be protective against impulsive scratching.

Purpose: This study is the first to analyze the relationship between agreeableness and induced scratching and between depression, self-consciousness, and induced itch in PS patients.

Methods: Twenty-four PS patients and 24 HC were shown two videos: an itch-inducing experimental video (EV) and a non-itch-inducing control video (CV). Induced itch/scratching was determined by calculating the difference in itch intensity/number of scratch movements between EV and CV. Validated questionnaires were used to measure agreeableness, depression, and self-consciousness.

Results: In accordance with our hypothesis, in PS patients, public self-consciousness was significantly positively associated with induced itch (r = 0.564; p < 0.001), and agreeableness was significantly negatively associated with induced scratching (r = -0.444; p < 0.05). In HC, the relationship between public self-consciousness and induced itch and between agreeableness and induced scratching were positive, but not significant.

Conclusions: This study showed distinct findings for PS patients and HC regarding the relationship between agreeableness and induced scratching. The relationship between public self-consciousness and induced itch was positive in both groups. The distinct finding regarding agreeableness supports the idea that scoring low on this scale might be a protective factor for scratching in PS patients. Future research should investigate mediating factors of the outlined relationships.