Abstract:
Expectations play a crucial role in placebo and nocebo responses. Research has shown that the price of a placebo medication can influence the placebo effect, with a higher priced medication producing a higher placebo response than a cheaper or discounted medication. This is most likely due to altered expectations of the treatment, caused by assumptions of the relationship between medication price and quality. However, the influence of medication price on the nocebo effect has not been investigated. This study aimed to investigate how the price of a placebo medication influences placebo and nocebo effects. Additionally, this research aimed to investigate the effect of using an active placebo on placebo and nocebo effects, and whether using an active placebo has an impact on the price-effect. Eighty participants were recruited to take part in a study purportedly looking at whether a less expensive nasal spray bronchodilator has the same effectiveness as a more expensive nasal spray bronchodilator. Half of all participants were told that they had received the expensive medication and half were told that they had received the cheaper medication. Participants were also randomised to receive either an inert placebo bronchodilator nasal spray or an active placebo bronchodilator nasal spray, which contained 0.00014% capsaicin and caused minor nasal prickling upon administration. Analysis of the results revealed a higher nocebo response in participants in the expensive condition compared to participants in the cheap condition. Participants given the expensive medication attributed a significantly greater number of symptoms to the medication than the participants given the cheap medication (p = 0.05). No differences were found for placebo effects in the different price conditions; there were no differences between price conditions in the physiological or self-report breathing measures. A larger placebo effect was found for the active placebo nasal spray compared with the inert placebo nasal spray; participants who received the active placebo showed significantly greater improvement in lung function compared with the participants who received the inert placebo spray. This effect was found for both Forced Vital Capacity percent predicted (p = .016) and Forced Expiratory Volume in one second percent predicted, (p = .041). A larger nocebo effect was also found for the active placebo nasal spray compared with the inert placebo spray; there were significantly more symptoms attributed to the active placebo spray at post-medication (p <.001) and at the 24 hour follow-up (p = .021). There were also more unrelated symptoms attributed to the active placebo spray at the 24 hour follow-up (p = .032). The findings of this study demonstrate that the price of medication can influence the nocebo effect, likely through changing participants’ expectations about the treatment. This study also suggests that an active placebo which causes minor symptoms upon administration increases placebo responding, as well as increasing nocebo effects over time. These findings have important clinical implications because the way in which symptoms are interpreted affects medication adherence and therefore the long term success of the medical treatment. More research is needed to elucidate the mechanisms underlying these observed effects.