Psychoneuroimmunology and Chronic Pain

There is increasing evidence linking chronic pain to altered levels of central nervous system (CNS) inflammation and increased levels of perceived pain, anxiety, depression and sleep disturbance. However the inflammatory molecules responsible for physiologic and psychological components of chronic pain still warrant identification and exploration. Using central inflammation as a paramount factor in the creation and maintenance of chronic pain, this study aimed to investigate and describe the physical and psychological aspects of chronic pain associated with CNS inflammation. Using a cross-sectional correlational design, cerebrospinal fluid (CSF) inflammatory cytokine patterns present in 8 chronic pain participants were compared to inflammatory cytokine patterns present in 30 control CSF samples using multivariate analysis of variance (MANOVA), with analysis of variance (ANOVA) analysis as a follow-up. Levels of depression, anxiety, sleep disturbance and pain were measured in approximately 8 chronic pain patients and correlated to CSF levels of inflammatory cytokines using Pearson’s r, or Spearman’s Rho correlations. Demographic information was also explored for relationships to central inflammation and descriptive statistics were examined for responses. To our knowledge, this is the first study to describe increased CSF levels of Interleukin-8 (IL-8) in a population of majority Failed Back Surgery Syndrome chronic pain patients (F (1, 36) = 14.89, p \u3c 0.001, partial η2 = 0.293). Gender (F (1,6) = 7.782, p = 0.565), socioeconomic status (r = -0.823, p = 0.012) and educational level (r = 0.727, p = 0.041) were also correlated with central levels of inflammation, indicating that central physiologic changes may be related to host sex and psychosocial factors. All participants reported poor sleep quality and took at least one opioid medication, indicating that sleep and opioids may scaffold a portion of the chronic pain paradigm. This study richly describes the dynamic experience of chronic pain through the lens of Psychoneuroimmunology. Incorporating both physiologic and psychological aspects of the disease, this study describes an association between chronic pain, central inflammation, gender, socioeconomic status, opioid medications and poor sleep quality. Thus, the future of pain treatment must consider these aspects when treating patients and look to future studies for possible new treatment options which target these factors