Prescription opioid analgesics rapidly change the human brain

Pain, 05/03/2011

The results add to a growing body of literature showing that opioid exposure causes structural and functional changes in reward– and affect–processing circuitry. Morphologic changes occur rapidly in humans during new exposure to prescription opioid analgesics.

Methods

  • Longitudinal, magnetic resonance imaging study
  • 10 individuals with chronic low back pain were administered oral morphine daily for 1month
  • High–resolution anatomical images of the brain were acquired immediately before and after the morphine administration period

Results

  • Regional changes in gray matter volume were assessed on the whole brain using tensor–based morphometry, and those significant regional changes were then independently tested for correlation with morphine dosage
  • Thirteen regions evidenced significant volumetric change, and degree of change in several of the regions was correlated with morphine dosage
  • Dosage–correlated volumetric decrease was observed primarily in the right amygdala
  • Dosage–correlated volumetric increase was seen in the right hypothalamus, left inferior frontal gyrus, right ventral posterior cingulate, and right caudal pons
  • Follow–up scans that were conducted an average of 4.7months after cessation of opioids demonstrated many of the morphine–induced changes to be persistent.
  • In a separate study, 9 individuals consuming blinded placebo capsules for 6weeks evidenced no significant morphologic changes over time

Print Article Summary