Patient expectations can affect drug efficacy

The mind may affect pain medication outcomes more than previously believed.
A new study published in Science Translational Medicine found that patients’ expectations regarding the effects of pain medications influence medication efficacy as well as the pain-related brain pathways activated during treatment.

Researchers at the University of Oxford in the United Kingdom and other universities exposed healthy study participants to pain-provoking heat and gave them the opioid remifentanil (Ultiva). Participants were tested in 3 groups: those who expected a positive analgesic effect, those who had a negative expectation of analgesic effect, and those who had no expectation connected with pain relief. Using functional MRI brain testing, the researchers observed differences in neural activity in the brain regions that take part in coding pain intensity.

Positive expectation effects were associated with activity in the endogenous pain modulatory system; negative expectation effects were associated with activity in the hippocampus.  “On the basis of subjective and objective evidence, we contend that an individual’s expectation of a drug’s effect critically influences its therapeutic efficacy,” wrote lead author Ulrike Bingel, MD, with the University of Oxford.

“Doctors shouldn’t underestimate the significant influence that patients’ negative expectations can have on outcome,” said Irene Tracey, PhD, of the Centre for Functional Magnetic Resonance Imaging of the Brain at Oxford University, who led the research.
According to Tracey, people with chronic pain often have seen many doctors and tried many drugs that haven’t worked for them. “They come to see the clinician with all this negative experience, not expecting to receive anything that will work for them. Doctors have almost got to work on that first, before any drug will have an effect on their pain,” Tracey said.