Brain corticostriatal circuits are important for understanding chronic pain and highly relevant to motivation and cognitive processes. It has been demonstrated that in patients with chronic back pain, altered nucleus accumbens (NAcc)—medial prefrontal cortex (MPFC) circuit fMRI-based activity is predictive of patient outcome. We evaluated the NAcc-MPFC circuit in patients with another chronic pain condition, fibromyalgia, to extend these important findings. First, we compared fMRI-based NAcc-MPFC resting-state functional connectivity in patients with fibromyalgia (N = 32) vs. healthy controls (N = 37). Compared to controls, the NAcc-MPFC circuit’s connectivity was significantly reduced in fibromyalgia. In addition, within the fibromyalgia group, NAcc-MPFC connectivity was significantly correlated with trait anxiety. Our expanded connectivity analysis of the NAcc to subcortical brain regions showed reduced connectivity of the right NAcc with mesolimbic circuit regions (putamen, thalamus, and ventral pallidum) in fibromyalgia. Lastly, in an exploratory analysis comparing our fibromyalgia and healthy control cohorts to a separate publicly available dataset from patients with chronic back pain, we identified reduced NAcc-MPFC connectivity across both the patient groups with unique alterations in NAcc-mesolimbic connectivity. Together, expanding upon prior observed alterations in brain corticostriatal circuits, our results provide novel evidence of altered corticostriatal and mesolimbic circuits in chronic pain.

Previous research has demonstrated the importance of the corticostriatal circuit in chronic pain. By focusing on nucleus accumbens (NAcc) circuits related to reward, we aimed to clarify how altered brain reward systems contribute to chronic pain. Using resting-state functional magnetic resonance imaging, we compared NAcc-medial prefrontal cortex (MPFC) functional connectivity in patients with fibromyalgia vs. healthy controls. Among patients, we analyzed the extent to which functional connectivity correlated with clinical measures. We also examined NAcc functional connectivity to subcortical regions. Lastly, we compared our results to a separate dataset of patients with chronic back pain. We identified robust NAcc-MPFC functional connectivity among patients with fibromyalgia and healthy controls, with no significant group differences. We found a positive correlational trend between NAcc-MPFC functional connectivity and total mood disturbance. Notably, patients with fibromyalgia showed significantly reduced functional connectivity of the right NAcc with mesolimbic circuit regions compared to controls. These results were largely similar to the results from the separate dataset. Our results provide novel evidence of intact corticostriatal but altered subcortical functional connectivity of the NAcc during resting-state in chronic pain and suggest that measured connectivity may relate to changes in mood and the level of cognitive demand during fMRI-based measurement.