How can we use expectations to improve the treatment of psoriasis?

Psoriasis is a chronic inflammatory, non-contagious skin disease that develops due to a genetic predisposition and can also affect the joints in the form of arthritis. Psoriasis has a significant impact on the people affected. It is frequently only treated with topical treatments such as creams and ointments, but often, these are not sufficiently effective. For some years now, internal treatment using so-called biologics has also been available: These are antibodies that bind to certain signalling molecules of the immune system and therefore slow down the excessive inflammatory response in psoriasis. However, these treatments are very expensive and their active ingredients can cause side effects.

Stress and anxiety have a negative influence on symptoms

Project A12 seeks to improve treatment for psoriasis patients within the scope of the currently available options, by making use of expectation effects. Studies suggest that factors such as stress or anxiety can negatively influence the progression of inflammatory skin diseases and the occurrence of itching and pain. However, many sufferers have endured years of unsuccessful treatment attempts and have become depressed and sceptical about new therapeutic approaches. For these patients, it might be helpful to specifically strengthen positive expectations in order to alleviate symptoms and make them more open to new, promising treatments. Nevertheless, during the first funding period of Project A12, we found that improving expectations alone has only a limited impact on the objective course of illness.

Can reinforcement learning and pharmacological conditioning lead to fewer side effects?

In the second funding period, we are therefore broadening and optimizing our approach by additionally employing reinforcement learning through pharmacological conditioning. This principle is based on the observation that in certain cases, the body is able to remember the effect of a medication and partly replicate this effect itself: For example, one study found that the effect of a cream containing cortisone in people with psoriasis was maintained even after it had been replaced by a placebo ointment. Project A12 examines whether this phenomenon is also possible in the case of internal treatment with biologics: If so, patients’ side effects could be reduced and they might need less of the very expensive mediation.

An experimental skin allergy model

In addition to the clinical studies, in Project A12, we are also working with healthy volunteers on an experimental skin allergy model, which will enable us to examine the effects not only of positive expectations but also of negative expectations. How do such expectations influence the subjective and objective symptoms of allergic dermatitis? And how do they affect the subjective and objective efficacy of treatments? We will be tackling these questions in the coming years.