Recent imaging studies of substance dependence including illicit opioids in non-chronic pain showed abnormalities in brain regions involved in cognitive control (e.g., dorsolateral prefrontal cortex; DLPFC). Imaging studies of chronic pain including CLBP also revealed aberrant brain activity within the salience network. However, it is unclear how opioid status in chronic pain patients affects functional connectivity of brain regions associated with cognitive control (DLPFC) and pain processes (insula).

To investigate whether opioid therapy in patients with chronic low back pain (CLBP) is associated with altered functional connectivity during performance of cognitive control task.

Twenty CLBP patients (10 females, 10 males, mean age, 46.5 years), half of whom on long-term opioid regimen, underwent BOLD functional MRI scan while performing a cognitive control task. Briefly, patients received acute thermal pain in the lower back inside a 3T scanner and were asked to reframe their pain by re-interpreting the meaning of the situation to make it less aversive. Following image preprocessing in SPM12, seed-to-voxel analysis was performed to assess functional connectivity between selected seed regions (left DLPFC, and left insula), and all other voxels in the brain.

The first seed-to-voxel analysis with left DLPFC as a seed revealed decreased functional connectivity in opioid-dependent CLBP compared with opioid-naïve CLBP patients between the left DLPFC and two voxel clusters: the right medial orbitofrontal cortex (a key neural substrate of decision-making), and the left supplementary motor area. The second seed-to-voxel analysis with left insula as a seed showed decreased coupling between the insula and right medial prefrontal cortex (Brodmann's areas 9/10).