Great Expectations: The Placebo Effect in Parkinson’s Disease
Our understanding of the neural mechanisms underlying the placebo effect has increased exponentially in parallel with the advances in brain imaging. This is of particular importance in the field of Parkinson’s disease, where clinicians have described placebo effects in their patients for decades. Significant placebo effects have been observed in clinical trials for medications as well as more invasive surgical trials including deep-brain stimulation and stem-cell implantation. In addition to placebo effects occurring as a byproduct of randomized controlled trials, investigation of the placebo effect itself in the laboratory setting has further shown the capacity for strong placebo effects within this patient population. Neuroimaging studies have demonstrated that placebos stimulate the release of dopamine in the striatum of patients with Parkinson’s disease and can alter the activity of dopamine neurons using single-cell recording. When taken together with the findings from other medical conditions discussed elsewhere in this publication, a unified mechanism for the placebo effect in Parkinson’s disease is emerging that blends expectation-induced neurochemical changes and disease-specific nigrostriatal dopamine release.
KeywordsPlacebo effect Parkinson's disease Expectation Dopamine and reward
- McRae C, Cherin E, Yamazaki TG, Diem G, Vo AH, Russell D, Ellgring JH, Fahn S, Greene P, Dillon S, Winfield H, Bjugstad KB, Freed CR (2004) Effects of perceived treatment on quality of life and medical outcomes in a double-blind placebo surgery trial. Arch Gen Psychiatry 61(4):412–420PubMedCrossRefGoogle Scholar
- Watts RL, Freeman TB, Hauser RA, Bakay RAE, Ellias SA, Stoessl AJ, Eidelberg D, Fink JS (2001) A double-blind, randomised, controlled, multicenter clinical trial of the safety and efficacy of stereotaxic intrastriatal implantation of fetal porcine ventral mesencephalic tissue (NeurocellTM-PD) vs. imitation surgery in patients with Parkinson’s disease (PD). Parkinsonism Relat Disord 7(S87)Google Scholar