240) Depressive symptoms and sleep efficiency mediate racial differences in endogenous pain facilitatory processes

Previous work conducted by our group revealed that older African Americans demonstrate significant hyperalgesia and augmented endogenous pain facilitation when compared to older non-Hispanic Whites. Psychological and behavioral factors that may help explain racial differences in the experience of pain among older adults remain largely unexplored. Thus, the current study sought to examine depressive symptoms and sleep efficiency as sequential mediators of racial differences in endogenous pain facilitatory processes. A total of 50 (26 African Americans and 24 non-Hispanic White) community-dwelling adults without chronic pain (mean age 50 years; range 22 to 77 years) initially completed the Center for Epidemiological Studies Depression Scale (CES-D) prior to seven consecutive nights of sleep monitoring with actigraphy in the home environment. Participants then returned to the laboratory for assessment of endogenous pain facilitation using a mechanical temporal summation protocol. Temporal summation was examined at both the dorsal hand and ipsilateral trapezius using fine pressure, results of which were then averaged across sites for an overall measure of mechanical temporal summation. Results supported the predicted three-path mediation model (95% Confidence Interval: -2.325 to -0.086). African American race was associated with greater depressive symptoms (t = -2.08, p = .043), which in turn was associated with poorer sleep efficiency (t = -2.55, p = .014), which was subsequently associated with augmented temporal summation of mechanical pain (t = -4.11, p < .001). Sex, education level, age, and risk for obstructive sleep apnea (assessed using the STOP-BANG questionnaire) were included in the analyses as covariates. This study lends support for the negative impact of depressive symptoms on sleep efficiency, and suggests that both sequentially mediate racial differences in endogenous pain facilitation. Additionally, it provides a foundation for incorporation of interventions intended to reduce depressive symptoms and improve sleep efficiency in those at risk for chronic pain.