Pruritic skin diseases, psychological stress, and the itch sensation. A reliable method for the induction of experimental pruritus.

A method of inducing controlled levels of terminable itching was developed. This method consists of administering constant monophasic pulsations of electric current by means of noninvasive electrodes. Once experimental pruritus had been reliably reproduced, two variables, hypothesized to be relevant to the perception of itching, were investigated, viz, the presence of a positive or a negative history of a pruritic dermatosis, and the presence of a high or low level of psychological stress. Both variables were found to be related to the perception of itching, but in different manners. A positive history of a pruritic dermatosis lowered the threshold for the perception of itch stimuli, while a high level of psychological stress enhanced the ability to discriminate among the more intense itch stimuli, with no effect on the itch threshold.