Friday, October 16, 2009

Study Finds Analgesic Placebo Effects in Spine

Benefits of placebo effects for aiding pain relief are appearing more frequently in the medical news these days. Most recently, a study by German researchers appearing in the journal Science describes how analgesic placebo effects inhibit pain perception directly in the spinal cord, which may have implications for enhancing pain therapies.

Falk Eippert and colleagues at Germany's University Medical Center Hamburg-Eppendorf enrolled 15 healthy young men in their experiment [Eippert et al. 2009]. First, the researchers gauged subjects’ pain thresholds by applying heat to their arms. Next, two identical but inactive creams were applied to the subjects’ arms, with instructions that one was a powerful “pain reliever cream” and the other was a latent "control cream." When heat was applied to the treated areas to stimulate pain, the fake pain-reliever cream reduced pain sensations (placebo effect); whereas, the control cream offered no pain relief. MRI scans performed during the tests showed that when heat was applied to the arms treated with the fake pain-reliever cream there was less activity in the dorsal horns of the subjects’ spinal cords.

Commentary: The researchers note that the analgesic placebo effects demonstrate the impact that psychological factors can have on pain perception; however, their study does not help to explain the mind-body connections between the men's beliefs about the creams and how they responded to pain from the heat. Importantly, however, in this small study (more like a case series) there was a direct reduction of nociception in the spinal cord as a result of placebo effects, suggesting that psychological factors can act on the earliest and most elemental stages of pain processing in the central nervous system. The power of analgesic placebo effects should not be dismissed or ignored; as we noted recently, such effects have been found to play important roles in the treatment of gastrointestinal pain disorders in children (see webpost 10/7/09). While the psychological dynamics at work in children may be different, this study by Eippert and colleagues recommends that mind-body influences on pain relief also may be worthy of consideration in adults. Further research is necessary to clarify how placebo effects might be invoked clinically to enhance therapies for pain.

Reference: Eippert F, Finsterbusch J, Bingel U, B├╝chel C. Direct evidence for spinal cord involvement in placebo analgesia. Science. 2009 (Oct 16);326(5951):404 [see abstract here].