Chronic pain and the power of placebo
A new study has asked whether certain people with chronic pain should be given sugar pills to manage their symptoms. Scientists tap into the individual differences that make some people more susceptible to a placebo.
A placebo is a medical intervention — be it a pill, injection, or sham surgery — that has no therapeutic value.
The placebo effect refers to the real benefits that these inert interventions can have.
The simple act of taking a tablet can make a person feel its benefits.
However, this is not just a psychological phenomenon; it has a biological basis.
As one example, some studies have shown that a placebo can affect blood pressure; a clear physiological response.
However, the placebo effect is most apparent in conditions that rely on self-reporting of symptoms, such as anxiety, irritable bowel syndrome, and chronic pain.
In chronic pain trials, for instance, the placebo effect can often be as great as the response to the treatment that is being tested. In actual fact, the response to a placebo can sometimes be larger than the response to conventional treatment.
Placebo as a viable option
Because the standard drugs that are used to treat chronic pain can have significant adverse effects over time, the potential for an inert tablet to benefit some patients is of great interest. One of the difficulties, though, is that not everyone is equally susceptible to the placebo effect.
A recent study set out to probe this problem: could it be possible to predict the size of someone's response to a placebo before they take it? The results were recently published in the journal Nature Communications.
To investigate, scientists at Northwestern University in Illinois studied 60 volunteers with chronic back pain. They split the group into two study arms; one took either the drug or placebo, while another attended the clinic but underwent no treatment.
Each person completed a number of in-depth questionnaires that assessed their personality and the type of pain that they experienced. They also went through four neuroimaging sessions.
As expected, some individuals who took the placebo felt significant pain relief; these participants were then examined further.
The scientists found that those who responded to the placebo had asymmetry in their subcortical limbic system, which is a part of the brain involved in emotion.
Particularly, the investigators found it to be larger on the right side than on the left. These people also had a larger cortical sensory area than those who did not respond to the placebo.
Also, volunteers with a strong placebo response were more emotionally self-aware, mindful of their environment, and sensitive to painful situations.
