Objective: The aim of the present study is to determine how the expectation of receiving a therapeutic treatment influences Parkinson’s disease (PD) symptoms.

Background: The placebo effect can be observed in different medical conditions, including PD. In particular, it has been shown that the expectation of receiving an anti-parkinsonian drug produces clinical benefits similar to real treatments. Moreover, after previous exposures to effective treatments, the administration of a placebo produces robust clinical improvements. In the present study we investigated the influence of positive expectations on different outcome measures. Beside the traditional clinical outcome, we investigated two common problems in PD patients: perceived fatigue and difficulties in motor preparation.

Methods: 38 PD patients were recruited for the study. They were asked to lift a load with their index finger and to repeat the movement until exhaustion in two different conditions: an OFF condition (without L-Dopa) and an ON condition (with L-Dopa). Patients were randomly assigned to two different groups: 100% group or 50% group, based on the percentage of L-Dopa received. Patients in 100% group received their standard L-Dopa dose, whereas patients in the 50% group received the 50% of their standard dose. Both groups were informed that they would have received their standard daily dose of L-Dopa, in order to induce the expectation of clinical and motor improvement. Different motor and clinical parameters have been recorded. EEG has been used to measure the Readiness Potential (RP), an event-related potential involved in motor preparation and influenced by fatigue. Number of repetitions and rate of perceived exertion were recorded to assess the motor improvement. Clinical symptoms were assessed using the UPDRS.   

Results: In the ON condition, we found that the 100% group improved in both clinical and motor parameters (decrease in perceived fatigue, increase of motor repetitions and reduction of RP amplitude). The same results were obtained in the 50% group. More importantly, no significant differences between groups were observed.

Conclusions: These data indicate that expectations and previous experiences plays a crucial role in placebo responsiveness. This study opens important clinical implications, such as the possibility to reduce L-dopa intake alternating drugs with placebos, maintaining a good clinical condition during the standard PD treatment.

References: Benedetti, F. Frisaldi, E., Carlino, E., Giudetti, L., Pampallona, A., Zibetti, M., Lanotte, M., Lopiano, L. (2016). Teaching neurons to respond to placebos. Journal of Physiology, 594(19), 5647-60.

Frisaldi, E., Carlino, E., Lanotte, M., Lopiano, L., & Benedetti, F. (2014). Characterization of the thalamic-subthalamic circuit involved in the placebo response through single-neuron recording in Parkinson patients. Cortex; a Journal Devoted to the Study of the Nervous System and Behavior, 60C, 3–9.

« Back to 2017 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/the-effect-of-expectation-on-parkinsons-disease-an-eeg-study/