To test the hypothesize that psoriasis
patients treated under a partial schedule of pharmacologic (corticosteroid) reinforcement would show less severe symptoms and relapse than those given the same amount of drug under standard conditions. Behavioral conditioning
as an inherent component of many pharmacotherapeutic protocols has never been examined.
A double-blind, simple randomization intervention was conducted with 46 patients from California and New York. Initially, lesions were treated with 0.1% acetonide triamcinolone under standard treatment conditions. Thereafter, a Standard Therapy group continued on continuous reinforcement (active drug every treatment) with 100% of the initial dose; Partial Reinforcement
patients received a full dose 25% to 50% of the time and placebo medication other times; Dose Control patients received continuous reinforcement with 25% to 50% of the initial dose.
Severity of disease scores in California neither supported nor refuted the hypothesis. In New York, where there was no difference between Partial Reinforcement
and Dose Control groups at baseline, partial reinforcement
effected a greater reduction in lesion severity than Dose Control conditions and did not differ from Standard Therapy patients receiving two to four times more drug. For the entire population, the frequency of relapse under partial reinforcement
(26.7%) was lower than in Dose Control patients (61.5%) and did not differ from full-dose treatment (22.2%).
A partial schedule of pharmacotherapeutic reinforcement could maintain psoriasis
patients with a cumulative amount of corticosteroid that was relatively ineffective when administered under standard treatment conditions. Conceivably, corticosteroid administration only one quarter or half as frequently as currently prescribed is sufficient to treat psoriasis
. We posit, however, that these preliminary observations implicate conditioning
processes in—and for the design of—regimens of pharmacotherapy
PSS = Psoriasis Severity Scale; CS = conditioned stimulus; UCS = unconditioned stimulus.