Reduced doses of psoriasis treatment, when mixed with placebo, are just as effective as standard therapy for preventing relapse and reducing severity, a new randomized, double-blind study found.
The study, recently published online in Psychosomatic Medicine, was modeled after the concept of classical conditioning in which a subject can be trained to react to a stimulant. Investigators hypothesized that psoriasis patients could be conditioned toward better outcomes by being told they were receiving a higher dosage or more frequent corticosteroid reinforcement than they actually were.
Forty-six patients (83% white and 56% male) with mild to moderate psoriasis were divided into three groups. The standard-therapy group (18 patients) received continuous reinforcement of 0.1% triamcinolone acetonide (Aristocort A) twice daily to a randomly selected target lesion, while a commercial moisturizing cream was applied to a comparable control lesion, reported Robert Ader, Ph.D. and his colleagues.
Patients in the partial-reinforcement group (15 patients) received the same 0.1% dose of Aristocort A as the standard therapy group, but in only a portion of the syringes administered to them for treatment. The remainder of the syringes contained a placebo ointment of the same color and fragrance as the standard reinforcement. The investigators dubbed the ointment the “conditioned stimuli.”
The dose-control group (13 patients) received continuous reinforcement throughout the trial, but with only 25% or 50% of the active ingredient administered in each dosage, noted Dr. Ader of the department of psychiatry at the University of Rochester (N.Y.), and his colleagues.
Approximately half the patients were studied at the University of Rochester and the other half at Stanford (Calif.) University between 2001 and 2006.
Evaluations of the psoriatic lesions were made weekly throughout the maintenance (conditioning) period and experimental period by a blinded dermatologist (Psychosom. Med. 2009 Dec. 22 [doi:10.1097/PSY.0b013e3181cbd38b]).
Initially, there were no differences in the severity between target and control lesions on patients in all groups, but during the 8-week experimental period, 61.5% of patients in the dose-control group relapsed, while only 22.2% of patients in the standard-therapy group relapsed. The incidence of relapse in the partial-reinforcement group was 26.7%.
Researchers in New York did find, however, that final severity outcomes measured by a modified Psoriasis Severity Scale produced no differences between the partial reinforcement group and the standard therapy group, even though patients in the latter received two to four times more active ingredient.
Psoriasis severity in Rochester’s dose-control group saw a steady increase throughout the 8-week experimental period (patients saw 44% less improvement between target and control lesions, compared with the partial reinforcement group). In California, disease severity outcomes neither supported nor refuted the hypothesis.
“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,” wrote Dr. Ader and his investigators. “Conceivably, corticosteroid administration only one quarter or half as frequently as currently prescribed is sufficient to treat psoriasis.”
Dr. Ader and his colleagues reported no conflicts of interest. The study was supported, in part, by grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the National Center for Complementary and Alternative Medicine.