How Does Choice Influence Drug Response?

Previous research has shown that reducing patient choice both leads to higher levels of nocebo responding and diminishes the placebo effect (Bartley et al., 2016). This study seeks to explore the mechanisms through which this process occurs. One possibility is that reducing choice focuses attention to negative information about the medication. This study will investigate whether limiting choice will increase recall of negative information and influence both placebo and nocebo responding. As the medication in this research will be a placebo, reported side effects will be nocebo effects (the negative side effects of an inert agent) and reported medication efficacy will be placebo effects. The placebo itself comprises a capsule containing lactose monohydrate, microcrystalline cellulose and magnesium stearate, and will be administered orally at a single time point during the intervention session. Participation will involve randomisation to either a choice group (in which participants will select one of two “beta blockers” to take) or a no-choice group (participants will be led to believe that they will randomly receive one of the two beta blockers, when in actual fact, they will receive their non-preferred option). Participants will receive a beta blocker information brochure, which was designed specifically for this study and gives an overview of the mechanisms of beta blockers, their potential side effects, and how they may be useful for anxiety. After taking the placebo, participants will wait 10 minutes, and will be told that during this time period, the beta blocker should take effect. Immediately following this latent period, they will take part in 3 short tasks to simulate an examination setting (these include digit span, digit symbol matching, and a recall task). Heart rate and blood pressure measurements will be recorded at three time points throughout the session, along with questionnaires about anxiety and side effects. It is expected that the 3 exam-simulating tasks will take participants 15 minutes to complete. The overall session, including the completion of questionnaire and the repeated measurements of heart rate and blood pressure, will take 50 minutes total. The following day, participants will complete a brief follow-up questionnaire on anxiety and side effects experienced over the prior 24 hours. This will be sent via a link and completed online.