A Positive Mood Induction for Reducing the Formation of Nocebo Effects from Side Effect Information

Background Providing treatment side effect information can increase the occurrence of side effects through nocebo effects. Nocebo effects from side effect information raise a dilemma for health care, as there is an ethical obligation to disclose potential unpleasant treatment information to patients. Purpose To test the hypothesis that a positive mood induction can block the development of nocebo effects that result from treatment side effect information. Methods In a laboratory setting, healthy participants were assigned to one of four conditions in a between-subjects randomized factorial trial. First, participants took part in a mood induction procedure, with half receiving a positive mood induction and the other half a neutral mood induction. Next, participants were told they would experience transcranial direct current stimulation (tDCS). Prior to a sham tDCS task, half of the participants were informed that headache pain is a side effect of tDCS, whereas the other half were not given this information. Results In the neutral mood condition, the provision of headache side effect information lead to a greater occurrence of headaches, more frequent headaches, and a higher maximum level of headache pain as compared to those given no side effect information. In the positive mood condition, a similar increase in headache pain did not manifest from the provision of side effect information. Conclusions This is the first experiment to find that a positive mood induction can block the formation of nocebo effects that arise from side effect information. Inducing positive moods may be an effective strategy for reducing nocebo effects in a variety of clinical settings.