Research into placebo effect among Parkinson’s patients

May 14 2004

Research reported by education Prof. Cynthia McRae provides strong evidence for significant mind-body connections among patients who participated in a double-blind Parkinson’s surgical trial. The findings were published in the April Archives of General Psychiatry.

Forty patients from the United States and Canada participated to determine the effectiveness of transplantation of human embryonic dopamine neurons into the brains of those with advanced Parkinson’s disease. Twenty patients received the transplant, while 20 more were randomly assigned to undergo a sham surgery.

McRae, a counseling psychologist, reports that the “placebo effect” was very strong among the 30 patients who participated in the quality-of-life portion of the study.

“Those who thought they received the transplant reported better quality of life at 12 months than those who thought they received the sham surgery, regardless of which surgery they actually received,” McRae says. Measures of improved quality of life included physical functioning, social support and a global rating of change since surgery.

One of study’s the most impressive results was that objective ratings of neurological functioning by medical personnel showed a similar effect. In the Archives article, McRae writes: “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. She was surprised to learn after the double-blind was lifted that she had received the sham surgery.

The findings have both scientific and practical implications, says the study’s co-author, Dan Russell of the Institute for Social and Behavioral Research at Iowa State University.

“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,” Russell says.

McRae notes that similar results related to the placebo effect have been found in other studies of patients with Parkinson’s disease. She says that there is a need for placebo controls in studies evaluating treatment for Parkinson’s, as the placebo effect seems to be particularly strong in this disease.

McRae has had a strong interest in Parkinson’s disease ever since her father was diagnosed with the disease. When she heard the surgeries were taking place in Denver, she expressed interest in conducting a follow-up quality-of-life study and later received a grant from the National Institute of Neurological Disorders and Stroke. http://www.du.edu