Depression modulates pruritus perception: a study of pruritus in psoriasis, atopic dermatitis, and chronic idiopathic urticaria.

Pruritus, or itching, is the most common symptom of dermatologic disease. Psychologic factors can affect pruritus, and in an earlier study of inpatients with moderate to severe psoriasis, we observed that the degree of depressive psychopathology directly correlated with pruritus severity. In this study we investigated the relation between pruritus and depression among a group of patients (N = 252) with a wide range of pruritic skin disorders, including outpatients with mild to moderate psoriasis (N = 77), atopic dermatitis (N = 143) and chronic idiopathic urticaria (N = 32). All patients self-rated the severity of their pruritus on a 10-point scale and completed a battery of psychologic ratings, including the Carroll Rating Scale for Depression (CRSD). We observed a direct correlation (Pearson's r = .34, p < .0001) between pruritus severity and the CRSD score. The correlations between pruritus severity and CRSD scores for each individual diagnostic group were as follows: psoriasis: Pearson's r = .32, p = .004; atopic dermatitis: Pearson's r = .21, p = .013; and chronic idiopathic urticaria: Pearson's r = .34, p = .06. When the subjects with pruritus scores less than 5.5 were compared with subjects with pruritus scores greater than 5.5, significant differences (p < .05) in depression scores were found for all three dermatoses by the Mann-Whitney U test. The depressed clinical state may reduce the threshold for pruritus.