IIRC, studies have also shown that the cost of the placebo had a direct correlation to the efficacy. Ah yes: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4345649/

Conclusion:

Expensive placebo significantly improved motor function and decreased brain activation in a direction and magnitude comparable to, albeit less than, levodopa. Perceptions of cost are capable of altering the placebo response in clinical studies.