In the latest issue of Neuron, David Scott and colleagues report on the neuroscience behind the placebo effect. Though subject to interpretation, the placebo effect refers to the way in which psychological expectation can ameliorate illness in the absence of a proven remedy. Scott et al. asked subjects to rate their expectations for pain relief before injecting them with saline. After injection, subjects were asked to rate the perceived analgesic effect.
Scott et al. wanted to see if these self-reports correlated with dopamine release in the nucleus accumbens, a brain region thought to be involved in reward processing. They measured local dopamine release using Positron Emission Tomography (or PET) and found that it correlated with expected pain relief as well as the mismatch between expected and perceived analgesic effect.
The more we understand about the placebo effect, the more we will be able to harness it in everyday clinical practice. Though this may seem to violate the principle of informed consent, a doctor may not necessarily need to lie when prescribing saline or sugar pills. For instance, a doctor could simply tell a patient that she is receiving an unproven medication that may relieve her suffering. This article in the Journal of Medical Ethics endorses the use of placebos in clinical practice. In fact, the authors make the case that sometimes placebo administration should be required.