Early life adversity increases risk for chronic post-traumatic pain, data from humans and rodents

Traumatic stress exposures (TSEs) are common in life. Although most individuals recover after a TSE, a substantial subset develop adverse post-traumatic neuropsychiatric sequelae such as chronic post-traumatic musculoskeletal pain (CPMP). Vulnerability factors for CPMP are poorly understood, which hinders identification of high-risk individuals for targeted interventions. One known vulnerability factor for many pain types is exposure to early life adversity (ELA), but few studies have assessed whether ELA increases risk for CPMP. This study used data from the Advancing Understanding of RecOvery afteR traumA study, a prospective human cohort study of TSE survivors, to test the hypothesis that ELA increases risk for CPMP. In addition, in secondary analyses, we assessed which subtypes of ELA (including childhood bullying) were most predictive of CPMP and whether a rat ELA model consisting of neonatal limited bedding, combined with single prolonged stress (SPS) in adulthood, would accurately model human findings. In Advancing Understanding of RecOvery afteR traumA study participants (n = 2480), using multinomial logistic regression modeling of 4 identified latent pain classes, we found that ELA increased vulnerability to the high unremitting pain class (odds ratio [OR] = 1.047, P < 0.001), the moderate pain class (OR = 1.031, P < 0.001), and the moderate recovery pain class (OR = 1.018, P = 0.004), with physical abuse, emotional abuse, and bullying being the strongest predictors of high pain class assignment. Similarly, in male and female Sprague Dawley rats, in comparison with SPS alone, neonatal limited bedding combined with SPS caused increased baseline sensitivity and prolonged mechanical hypersensitivity (F(11,197) = 3.22, P < 0.001). Further studies in animals and humans are needed to understand mechanisms by which ELA confers vulnerability to CPMP.