Medications aimed at lessening the symptoms of Parkinson’s disease are subject to the placebo effect. While it has long been known that certain Parkinson’s disease treatments have a positive impact upon the patient’s condition because of raised expectations, the phenomenon appears exaggerated when the patient thinks the drug is more expensive.
According to Dr. Alberto Espay, the lead author of the study, the placebo effect has been “well documented” in patients suffering from Parkinson’s. As a consequence, he maintains that the patient’s expectations are crucial to treatment efficacy.
Dr. Espay and colleagues are the first group of researchers to investigate the placebo response to Parkinson’s treatments of varying costs. Espay, who is also an associate professor of neurology at the UC Neuroscience Institute at the University of Cincinnati, discovered that Parkinson’s patients responded better to treatment when taking the more expensive drug. Almost 30 percent of patients saw an improvement in their motor skills after being given the more expensive drug, compared to when they were receiving treatment using the cheaper drug.
A total of 12 Parkinson’s patients were incorporated into the study, all of whom were informed that they would be injected with two formulations of a treatment. The researchers told their study participants that the two drug preparations had different manufacturing costs, but would likely have the same efficacy - a hypothesis that the researchers said they were testing for. The patients were also led to believe that the cheaper of the two injections cost a mere $100, with the other priced at, a less competitive, $1,500.
In fact, the injections were nothing more than saline solution.
Each of the 12 participants received their first injections, either “cheap” or “expensive.” After being told the effects of the first drug had eventually worn off, the team then administered the second injection to each patient.
Brain scans and motor skill tests were conducted before and after each injection to determine the impact that the placebos played on the study subjects. Looking at the functional magnetic resonance imaging (fMRI) scans of the patients, the researchers found their brain activity to be the same as that observed in patients who take the genuine Parkinson’s drug Levodopa.
The eight patients who said they expected the more expensive drug to offer greater benefit claimed they had seen the greatest improvement. Meanwhile, the other four patients, who said they anticipated there would be no difference between the two drugs, said they had experienced few changes.
In explaining the results, Dr. Espay believes that the patients who benefited from the “expensive” drug did so because of an increase in release of the neurotransmitter dopamine: “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.”
In the future, Dr. Espay hopes the different placebo responses will be exploited to bring about novel treatment strategies for the disease. In doing so, he believes practitioners may be able to enhance treatment efficacy, while driving down the dosage to avoid drug-related side-effects.
