Brain networks predicting placebo analgesia in a clinical trial for chronic back pain

Javeria A. Hashmi, Alex T. Baria, Marwan N. Baliki, Lejian Huang, Thomas J. Schnitzer, A. Vania Apkarian*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

78 Scopus citations

Abstract

A fundamental question for placebo research is whether such responses are a predisposition, quantifiable by brain characteristics. We examine this issue in chronic back pain (CBP) patients who participated in a double-blind brain imaging (functional magnetic resonance imaging) clinical trial. We recently reported that when the 30 CBP participants were treated, for 2 weeks, with topical analgesic or no drug patches, pain and brain activity decreased independently of treatment type and thus were attributed to placebo responses. Here we examine in the same group brain markers for predicting placebo responses - that is, for differentiating between posttreatment persistent CBP (CBPp) and decreasing CBP (CBPd) groups. At baseline, pain and brain activity for rating spontaneous fluctuations of back pain were not different between the 2 groups. However, on the basis of brain activity differences after treatment, we identified that at baseline the extent of information shared (functional connectivity) between left medial prefrontal cortex and bilateral insula accurately (0.8) predicted posttreatment groups. This was validated in an independent cohort. Additionally, by means of frequency domain contrasts, we observe that at baseline, left dorsolateral prefrontal cortex high-frequency oscillations also predicted treatment outcomes and identified an additional set of functional connections distinguishing treatment outcomes. Combining medial and lateral prefrontal functional connections, we observe a statistically higher accuracy (0.9) for predicting posttreatment groups. These findings indicate that placebo response can be identified a priori at least in CBP, and that neuronal population interactions between prefrontal cognitive and pain processing regions predetermine the probability of placebo response in the clinical setting.

Original languageEnglish (US)
Pages (from-to)2393-2402
Number of pages10
JournalPain
Volume153
Issue number12
DOIs
StatePublished - Dec 2012

Keywords

  • Chronic pain
  • Clinical trial
  • Cognitive
  • Emotion
  • Pain modulation
  • Placebo
  • Prediction
  • Prefrontal cortex
  • fMRI

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Anesthesiology and Pain Medicine

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