Projects investigating placebo effects in Parkinson's disease receive funds

The Michael J. Fox Foundation for Parkinson's Research announced funding for two projects investigating the placebo effect in Parkinson's disease.

Placebo treatments are harmless, inactive substances administered to some of the patients in a clinical trial to provide a baseline comparison for measuring the effects of active treatment given to other patients in the trial. The placebo effect -- in which patients who receive an inert substance nonetheless experience some or all benefits of active treatment -- is a topic of growing interest to Parkinson's researchers. The placebo effect has increasingly complicated the interpretation of outcomes from PD clinical trials, creating a significant hurdle to the development of new treatments. And it may have a greater impact in clinical trials for Parkinson's than other diseases, because it involves the dopamine system, which degenerates in PD.

As part of a clinical trial in dyskinesia announced by the Foundation earlier this month, a pilot study will seek to initially validate surveys that can predict how placebo response is impacted from person to person by disease- and treatment-related variables, as well as by individual personality characteristics of patients and investigators involved in clinical research. The pilot will assess the potential validity of the placebo surveys for other future clinical trials, as well as provide ancillary information on various dyskinesia rating scales' susceptibility to placebo effects. Researchers Mark Stacy, MD, of Duke University and Glenn T. Stebbins, PhD, of Rush University Medical Center will compile and develop surveys to be administered to patients and investigators at the outset of the study. These surveys will gather data on personal traits including optimism, social conformity and expectations of outcome. At the close of the trial, the survey results will be tracked with study outcomes to determine the impact of optimism and expectation of positive outcome on the effectiveness of different dyskinesia rating scales.

A Columbia University team led by Tor Wager, PhD, and Daphna Shohamy, PhD, will use functional magnetic resonance imaging (fMRI) to look at brain activity in Parkinson's patients as they execute specific motor and learning tasks, comparing how brain activity changes when the patients are given levodopa (the gold-standard treatment for Parkinson's disease) versus placebo. While previous imaging studies have demonstrated that placebo treatments can increase dopamine levels in patients' brains, there is little experimental evidence that these increased dopamine levels are tied to functional improvement on the Unified Parkinson's Disease Rating Scale (UPDRS), the tool used by clinicians to measure effects of experimental treatments. Drs. Wager and Sohamy will evaluate the potential of fMRI to provide such evidence. The goal is to more fully establish biological markers of placebo effects in PD and determine whether placebo effects lead to measurable functional improvement for patients.