Racial Differences in Head Pain and Other Pain-Related Outcomes after Mild Traumatic Brain Injury

Recent research suggests that mild traumatic brain injury (TBI) may exert deleterious effects on endogenous pain modulatory function, potentially underlying the elevated risk for persistent headaches following injury. Accumulating research also shows race differences in clinical and experimental pain, with African Americans (AA) generally reporting more severe pain, worse pain modulation, and greater pain sensitivity compared with Caucasians. However, race differences in pain-related outcomes following mild TBI have rarely been studied. The purpose of this study was to explore race differences in endogenous pain modulation, pain sensitivity, headache pain, and psychological factors among AA and Caucasian individuals with mild TBI in the first month following injury compared with healthy controls and across time. Patients with mild TBI were recruited from local emergency department trauma centers. Sixty-three participants with mild TBI (AAs: n = 23, Caucasians: n = 40) enrolled in this study and completed study sessions at 1-2 weeks and 1-month post-injury. Forty-one mild-TBI-free control participants (AAs: n = 11, Caucasians: n = 30), matched on age and sex, completed one study session. Assessments included a Headache Survey, Pain Catastrophizing Scale, Center for Epidemiological Studies-Depression Scale (CES-D), and quantitative sensory testing (QST) to measure endogenous pain modulatory function. QST included conditioned pain modulation (CPM) to measure endogenous pain inhibitory function and temporal summation (TS) of pain and pressure pain thresholds (PPTs) of the head to measure pain sensitization and sensitivity. Two-way analysis of variance (ANOVA) was used to determine whether the outcome measures differed as a function of race, mild TBI, and time. Mediation analysis was used to explore potential mediators for the race differences in headache pain intensity. The results showed that AA participants with mild TBI reported significantly greater headache pain and pain catastrophizing and exhibited higher pain sensitivity and worse pain modulation on QST compared with Caucasian participants with mild TBI. These same race differences were not observed among the healthy TBI-free control sample. The mediation analyses showed complete mediation for the relation between race and headache pain intensity by pain catastrophizing at 1-2 weeks and 1-month post-injury. Overall, the results of this study suggest that AAs compared with Caucasians are characterized by psychological and pain modulatory profiles following mild TBI that could increase the risk for the development of intense and persistent headaches following injury.