Brain imaging reveals pessimism as self-fulfilling prophecy

Painkillers could fail if you expect them to. Scientists use fMRI to show how a gloomy outlook towards your medical treatment may decrease the effectiveness of the drugs you take.
Written by Janet Fang, Contributor

From the files of ‘the power of positive thinking’:

By manipulating your expectations, you can double or halve the potency of the drugs you take.

Scientists show that a gloomy outlook towards medical treatment may decrease the effectiveness of the drugs – based on brain images of thoughts, feelings, and past experiences.

The findings suggest that neural activity could be used to gauge how well a drug works and that doctors may need to find ways to better deal with their patients’ beliefs.

So, to clarify just how brain mechanisms can control the way expectations interact with the biological effects of drugs, European researchers used functional magnetic resonance imaging (fMRI) to examine how grim or optimistic predictions alter brain activity in 22 healthy people.

They attached a thermal stimulator (for inducing and assessing painful heat) to each volunteer’s lower leg, setting the pain level to 70 (out of 100, self-reported).

And they injected a quick-acting painkiller called remifentanil (Ultiva) intravenously.

  1. First, the volunteers were told that the solution was a placebo. They reported feeling pain level 55.
  2. Then they were told that they’re getting remifentanil and that it would relieve the pain. This dropped their pain level to 39 – even though there was no real drop in painkiller dose.
  3. Finally, they were told that the pain would get worse. They reported a heightened pain level of 64. (Again, there was no change in the actual painkiller dosage.)

When they expected the drug to be effective, they weren’t disappointed. "We found that positive treatment expectancy substantially enhanced – doubled – the analgesic benefit of remifentanil,” says study author Ulrike Bingel of Oxford. “In contrast, negative treatment expectancy completely abolished remifentanil's painkilling effect.”

Looking at brain scans that visualize pain stimulation (pictured), the researchers found that the expectation of increased pain was accompanied by increased neuron activity in brain areas that mediate mood and anxiety.

When people expected the painkiller to work, there was far less activity in those parts of the brain. And, there was more neural activity in certain other brain regions that make it harder for pain signals to access the spinal cord and brain.

HealthDay News reports:

Bingel believes that the data "opens a new avenue of research," linking up drugs with patients' personalities and expectations in the context of specific medical conditions.

The findings also have implications for clinical practice, she said. "We believe that the beliefs, expectations and previous experiences with drug treatments should be more systematically assessed and integrated [by doctors] to optimize the overall treatment outcome."

In addition to the placebo effect, the study looks at the ‘nocebo effect,’ where patients warned about the ineffectiveness of a drug have a negative experience.

According to the study editors:

Patient education about treatments can help counteract this problem by shaping beliefs to maximize drug effectiveness. If appropriate treatments are accompanied by encouraging words, a pessimist could become an optimist about his future robust health, and thereby make it so.

The study was published in Science Translational Medicine last week. It was accompanied by a perspective piece.

Image: Science/AAAS

This post was originally published on Smartplanet.com

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