A strong placebo effect on perceived quality of life 1 year after surgery was found among patients with Parkinson's disease who thought they had received a cell transplant but who had undergone sham surgery, providing additional evidence for a significant mind-body connection, according to an article in the April issue of the Archives of General Psychiatry.

A total of 40 people in the US and Canada participated to determine the effectiveness of transplanting human embryonic dopaminergic neurons into the brains of persons with advanced Parkinson's disease. Half of the patients received the transplant, while another 20 patients were randomly assigned to a sham surgery condition.

Dr. Cynthia McRae, the lead author, noted that the placebo effect was strong among the 30 patients who participated in the quality of life portion of the study: “Those who thought they received the transplant at 12 months reported better quality of life than those who thought they received the sham surgery, regardless of which surgery they actually received.”

More importantly, objective ratings of neurological functioning by medical personnel showed a similar effect. The authors wrote, “medical staff, who did not know which treatment each patient received, also reported more differences and changes at 12 months based on patients’ perceived treatment than on actual treatment.”

One patient, for example, reported that she had not been physically active for several years before surgery, but in the year following surgery she resumed hiking and ice skating. When the double blind was lifted, she was surprised to find that she had received the sham surgery.

Although patient perceptions influenced their test scores, when the total sample of patients was grouped by the operation they received, patients who had the actual transplant surgery showed improvement in movement while, on average, patients who had sham surgery did not.

Professor Dan Russell, a coauthor, said the findings have both scientific and practical implications: “This study is extremely important in regard to the placebo effect because we know of no placebo studies that have effectively maintained the double-blind for at least 12 months. The average length of placebo studies is eight weeks.”

McRae also commented that although the sham surgery research design is somewhat controversial and has raised ethical concerns, the results of the current study show “the importance of a double-blind design to distinguish the actual and perceived values of a treatment intervention.”