People’s perceptions of the cost of a drug may affect how much they benefit from the drug — even when they are receiving only a placebo. The finding, from a new study of people with Parkinson’s disease led by Alberto J. Espay, M.D., of the University of Cincinnati, and Jerzy P. Szaflarski, M.D., Ph.D., of the University of Alabama at Birmingham, is published in the Jan. 28, online issue of Neurology, the medical journal of the American Academy of Neurology.
“Patients’ expectations play an important role in the effectiveness of their treatments, and the placebo effect has been well-documented, especially in people with Parkinson’s disease,” said Espay, study author. “We wanted to see if the people’s perceptions of the cost of the drug they received would affect the placebo response.”
For the study, 12 people with Parkinson’s disease were told that they would receive shots of two formulations of the same drug, with the second shot given after the benefits of the first shot had subsided. They were told that the formulations were believed to be of similar effectiveness, but that they differed in manufacturing cost — $100 per dose versus $1,500 per dose. Participants were told that the study was intended to prove that the drugs, while priced differently, were equally effective.
In reality, the participants received only a saline solution (placebo) for both injections, but were told they were receiving either the “cheap” or “expensive” drug first. Before and after each shot, participants took several tests to measure their motor skills and also had brain scans to measure brain activity.
“When patients received the ‘expensive’ drug first, their motor skills improved by 28 percent compared to when they received the ‘cheap’ drug, which was twice as much,” said Szaflarski, senior author of the study while on the faculty at the University of Cincinnati. He now is director of the Division of Epilepsy in the Department of Neurology at the University of Alabama at Birmingham. “On one test of motor skills, people’s scores improved from 29 to 22 points when taking the ‘expensive’ drug first, but improved by only 3 points when taking the ‘cheap’ drug. In addition, the ‘expensive’ drug decreased activation in the brain similar to that of the Parkinson’s drug levodopa, while the ‘cheap’ drug increased activation in the brain,” indicating differential responses to the medication cost.
“If we can find strategies to harness the placebo response to enhance the benefits of treatments, we could potentially maximize the benefit of treatment while reducing the dosage of drugs needed and possibly reducing side-effects,” Espay said.
Espay says that the placebo response may be stronger in people with Parkinson’s because the disease decreases the amount of dopamine in the brain and the placebo effect is known to increase the release of brain dopamine. Dopamine affects movement; but it also affects anticipation, motivation and response to new things. “People who receive the shots thinking they received a drug may have an ‘expectation of reward’ response, which is associated with the release of dopamine similar to the response to the reward itself,” he said.
The study received extra scrutiny from the university’s review board before it began, since it involved intentional deception of the participants. The review board found that the study complied with federal research regulations that allow waiver of the informed consent requirement, and that the deception would have no adverse effects on the rights or welfare of the participants.
After the study, the participants were told about the true nature of the study. “Eight of the participants said they did have greater expectations of the ‘expensive’ drug and were amazed at the extent of the difference brought about by their expectations,” Espay said. “Interestingly, the other four participants said they had no expectation of greater benefits of the more expensive drug, and they also showed little overall changes.”
The study was supported by the Davis Phinney Foundation for Parkinson’s. To learn more about Parkinson’s disease, please visit www.aan.com/patients.