Altered structural brain network topology in chronic migraine.

Despite its prevalence and high disease burden, the pathophysiological mechanisms underlying chronic migraine (CM) are not well understood. As CM is a complex disorder associated with a range of sensory, cognitive, and affective comorbidities, examining structural network disruption may provide additional insights into CM symptomology beyond studies of focal brain regions. Here, we compared structural interconnections in patients with CM (n = 52) and healthy controls (HC) (n = 48) using MRI measures of cortical thickness and subcortical volume combined with graph theoretical network analyses. The analysis focused on both local (nodal) and global measures of topology to examine network integration, efficiency, centrality, and segregation. Our results indicated that patients with CM had altered global network properties that were characterized as less integrated and efficient (lower global and local efficiency) and more highly segregated (higher transitivity). Patients also demonstrated aberrant local network topology that was less integrated (higher path length), less central (lower closeness centrality), less efficient (lower local efficiency) and less segregated (lower clustering). These network differences not only were most prominent in the limbic and insular cortices but also occurred in frontal, temporal, and brainstem regions, and occurred in the absence of group differences in focal brain regions. Taken together, examining structural correlations between brain areas may be a more sensitive means to detect altered brain structure and understand CM symptomology at the network level. These findings contribute to an increased understanding of structural connectivity in CM and provide a novel approach to potentially track and predict the progression of migraine disorders.This study is registered on ClinicalTrials.gov (Identifier: NCT03304886).

Injustice Appraisal, but not Pain Catastrophizing, Mediates the Relationship Between Perceived Ethnic Discrimination and Depression and Disability in Low Back Pain.

Despite growing evidence of significant racial disparities in the experience and treatment of chronic pain, the mechanisms by which these disparities manifest have remained relatively understudied. The current study examined the relationship between past experiences of racial discrimination and pain-related outcomes (self-rated disability and depressive symptomatology) and tested the potential mediating roles of pain catastrophizing and perceived injustice related to pain. Analyses consisted of cross-sectional path modeling in a multiracial sample of 137 individuals with chronic low back pain (Hispanics: n = 43; blacks: n = 43; whites: n = 51). Results indicated a positive relationship between prior discriminatory experiences and severity of disability and depressive symptoms. In mediation analyses, pain-related appraisals of injustice, but not pain catastrophizing, were found to mediate these relationships. Notably, the association between discrimination history and perceived injustice was significantly stronger in black and Hispanic participants and was not statistically significant in white participants. The findings suggest that race-based discriminatory experiences may contribute to racial disparities in pain outcomes and highlight the specificity of pain-related, injustice-related appraisals as a mechanism by which these experiences may impair physical and psychosocial function. Future research is needed to investigate temporal and causal mechanisms suggested by the model through longitudinal and clinical intervention studies. PERSPECTIVE: More frequent prior experiences of racial discrimination are associated with greater depressive symptomatology and pain-related disability in individuals with chronic low back pain. These associations are explained by the degree of injustice perception related to pain, but not pain catastrophizing, and were stronger among black and Hispanic participants.

Perceived injustice in chronic pain: an examination through the lens of predictive processing.

Chronic pain conditions have been shown to be exacerbated by psychological factors, and a better understanding of these factors can inform clinical practice and improve the efficacy of interventions. The current paper investigates perceived injustice, a novel psychosocial construct, within a framework influenced by the tenets of predictive processing. The proposed conceptual model derived from tenets of predictive processing yields a single hierarchical self-reconfiguring system driven by prediction, which accounts for a wide range of human experiences such as perception, behavior, learning and emotion. This conceptualization can inform the development and implementation of more targeted therapeutic interventions for chronic pain.