A new meta-analysis gives the most detailed look yet at the neuroscience of placebo effects.

© Image provided by M.Zunhammer et al.fMRI activity during pain is reduced in the areas shown in blue. Many of these are involved in constructing the experience of pain. Activity is increased in the areas shown in red and yellow, which involve the control of cognition and memory.
Much of the benefit that a person gets from taking a real drug or receiving a treatment to alleviate pain is due to an individual's mindset, not to the drug itself, according to previous research. Understanding the neural mechanisms driving this placebo effect has long been a challenge. A meta-analysis published in
Nature Communications finds that placebo treatments meant to reduce pain, known as placebo analgesia, reduce pain-related activity in multiple areas of the brain.
Previous research of this kind has relied on small-scale studies, so until now, researchers did not know whether the neural mechanisms underlying placebo effects observed to date would hold up across larger samples. This study represents the first large-scale mega-analysis, which looks at individual participants' whole brain images. It enabled researchers to look at parts of the brain they did not have sufficient resolution to see in the past. The analysis comprised 20 neuroimaging studies with 600 healthy participants. The results provide new insight on the size, localization, significance and heterogeneity of placebo effects on pain-related brain activity.
The research reflects the work of an international collaborative effort by the Placebo Neuroimaging Consortium, led by
Tor Wager, the Diana L. Taylor Distinguished Professor in Neuroscience and Ulrike Bingel, a professor at the Center for Translational Neuro- and Behavioral Sciences in the Department of Neurology at University Hospital Essen, for which Matthias Zunhammer and Tamás Spisák at the University Hospital Essen served as co-authors. The meta-analysis is the second with this sample and builds on the team's
earlier research using an established pain marker developed earlier by Wager's lab.
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