The placebo effect is well known, but researchers from the University of Cincinnati decided to test the theory that patients would respond better to a placebo that they thought had an enormous price tag.

A meta-analysis found that placebos used in clinical trials of Parkinson’s treatments improved symptoms by an average of 16 percent, the Los Angeles Times reports, and the University of Cincinnati team decided to study 12 patients with “moderately advanced” Parkinson’s in a clinic trial of “a new injectable dopamine agonist.” With Parkinson’s, patients lose brain cells that make dopamine, something this drug could combat.

The participants were told that they were taking two versions of experimental drugs that worked the same but were made differently, with one costing 15 times more than the other. They were actually given the same exact saline solution. The results showed that both improved motor function compared with a base line test, but those who took the $1,500 dose placebo had an improvement that was nine percent greater than the $100 per dose placebo. “Patients’ expectations have an important role in the efficacy of medical therapies,” the researchers wrote. The results were published Wednesday in the journal Neurology.