Placebo Responses to Original vs. Generic ASA Brands During Exposure to Noxious Heat: A Pilot fMRI Study of Neurofunctional Correlates.

OBJECTIVE

We studied the expectation effects associated with brands by labeling placebo interventions (original and generic analgesic) and investigating the potential differences in efficacy between the two placebos in dealing with noxious heat pain, as well as exploring the neurometabolic correlates of the placebo response.

DESIGN

We applied a two by two design with two identical placebo interventions that differed only in their labeling. One group was told that they received 500 mg of "Aspirin" (original brand) while the other group was told that they received a popular ASA generic (1A Pharma). After establishing the individual pain level of each subject, we measured pain intensities behaviorally before and after the intervention and looked for corresponding brain areas with increased hemodynamic response using functional magnetic resonance imaging.

RESULTS

At the behavioral level, we found decreases in pain intensity from baseline to the intervention condition with the original brand only. At the neuronal level, we specifically observed activations of the anterior insulae under the baseline conditions, complemented by activations of the dorsomedial prefrontal cortex after the interventions. A direct comparison of the two placebo conditions revealed higher values of activation for the bilateral dorsolateral (as well as dorsomedial) prefrontal cortex for the original brand.

CONCLUSION

Our data indicate a behavioral placebo response for the original brand only. Expectations by subjects appear to be triggered not only by the placebo treatment itself but also by the trusted brand, which thus serves as an enhanced placebo. Both processes appear to be based on fronto-cortical neural networks, as these areas showed significantly stronger activations with the original brand.