Nocebo Effect: Negative Beliefs Can Alter Drug Efficacy

Nocebo Effect: Negative Beliefs Can Alter Drug Efficacy
According to the study, it is likely that 'an individual's expectation of a drug's effect critically influences its therapeutic efficacy and that regulatory brain mechanisms differ as a function of expectancy.' (Photos.com)
3/6/2011
Updated:
10/1/2015
<a><img src="https://www.theepochtimes.com/assets/uploads/2015/09/91911249.jpg" alt="According to the study, it is likely that 'an individual's expectation of a drug's effect critically influences its therapeutic efficacy and that regulatory brain mechanisms differ as a function of expectancy.' (Photos.com)" title="According to the study, it is likely that 'an individual's expectation of a drug's effect critically influences its therapeutic efficacy and that regulatory brain mechanisms differ as a function of expectancy.' (Photos.com)" width="320" class="size-medium wp-image-1807219"/></a>
According to the study, it is likely that 'an individual's expectation of a drug's effect critically influences its therapeutic efficacy and that regulatory brain mechanisms differ as a function of expectancy.' (Photos.com)
A patient’s doubts about the effectiveness of a drug could affect how well the drug works, according to a study published in Science Translational Medicine on Feb. 16. This effect is known as the nocebo effect.

Researchers from Germany and England looked at the effectiveness of the painkiller remifentanil in 22 healthy adults. They assessed patients’ expectations, using MRI brain scans to image three different expectations about the drug’s analgesic effects—positive, negative, and neutral.

In the MRI scanner, heat was applied to a person’s leg in order to measure pain. Pain was rated by the participants on a scale of 1 to 100, with 70 being the point at which they felt that the heat application began to hurt.

The painkiller was administered intravenously, after an undisclosed control run, to measure the effects while there was no knowledge or expectation of treatment. The initial pain rating decreased from 66 to 55 on average.

Next, the participants were told that medication was about to begin. However, no change was made to the dosage, yet the pain rating dropped again, to 39 on average.

Lastly, the patients were told that medication had stopped and were warned that pain might increase. Although the dosage was not actually altered, pain intensity increased to 64. This figure is lower than the initial figure of 70, when individuals felt pain without any medication.

The MRI scans showed the pain networks in the patients’ brains responded to different extents according to their expectations at each stage, and corresponded to their reports of pain.

Overall, the team found that positive expectations doubled the efficacy of the drug, while negative expectations canceled out any analgesic effects.

According to the study, it is likely that “an individual’s expectation of a drug’s effect critically influences its therapeutic efficacy and that regulatory brain mechanisms differ as a function of expectancy.”

The research team proposed that a patient’s beliefs and expectations need to be accounted for during medication regimes, along with standard considerations, to optimize treatment outcomes.

“People with chronic pain will often have seen many doctors and tried many drugs that haven’t worked for them,” said study leader Dr. Irene Tracey at Oxford University’s Center for Functional Magnetic Resonance Imaging of the Brain, in a press release.

“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 also pointed out that the nocebo effect should be considered in the design of clinical trials in general.

“We should control for the effect of people’s expectations on the results of any clinical trial. At the very least we should make sure we minimize any negative expectations to make sure we’re not masking true efficacy in a trial drug.”
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