Many individuals with traumatic brain injury (TBI) experience cognitive, emotional, and functional deficits, all of which can contribute to chronic stress. Unfortunately, individuals with TBI often engage in less effective coping than non-brain-injured individuals, which has negative implications for rehabilitation. Differences in personality traits have been linked to individual differences in coping styles, physiological stress reactivity, and emotional disclosure. Research on personality and coping after TBI has been sparse. Thus, the present study examined the influence of TBI on the pattern of the relationships between personality, emotional expression, and stress reactivity. Eighty-one adults who sustained moderate to severe TBI and 76 significant others of individuals with TBI participated. Personality was assessed using the Behavioral Inhibition System/Behavioral Activation System (BIS/BAS) scale, and self-report of affectivity was measured with the Positive and Negative Affect Schedule (PANAS). Verbal and nonverbal emotional expression were gleaned from a 3-minute videotaped speech task for which participants were asked to talk about stressful aspects of recovery from brain injury. Physiological measures of stress were also collected during the speech task. Results indicate that the pattern of relations between personality, emotional expression, and stress reactivity are affected by TBI; however, consistencies between the groups were also found. Both groups showed similar patterns for BIS in terms of propensity toward negative affectivity, as well as concomitant verbal output of negative emotion. Significant others showed a distinctive pattern for BAS sensitivity, which was associated with positive affectivity and low nonverbal expressions of sadness relative to a propensity to express anxiety and anger during the emotional challenge. By comparison, people with TBI showed a global pattern for BAS sensitivity of heightened affectivity (positive and negative affectivity), as well as explicit verbal output reflecting negative emotionality. Like significant others, BAS was associated with the propensity toward nonverbal expression of anxiety during the emotional challenge; however, people with TBI expressed more happiness, and less anxiety and helplessness than did significant others. Impairments in awareness of deficits and impaired cognitive appraisal of stress following TBI are likely to have contributed to the finding that adults with TBI exhibited more happiness and less anxiety than significant others. In general, TBI appears to enhance BAS but not BIS, which is supported by higher BAS sensitivity as a function of TBI severity and relative to individuals without TBI. For both groups, BAS sensitivity was favorably related to acute stress reactivity. In fact, among people with TBI BAS was uniquely related to stress coping, beyond that explained by demographic and injury characteristics. Taken together, the findings generally depict a pattern in which BAS facilitates expression of emotion and may also buffer or relieve experience of stress during emotional challenge. The BIS/BAS theory of personality and scale appear to be promising avenues for future research in these regards. The present study provides insight into how brain injury affects the relations between personality, stress reactivity, and emotional expression. Findings also highlight the importance of considering personality traits when studying emotional expression. Future research investigating the utility of these associations to predict rehabilitation and quality of life outcomes among brain-injured individuals has the potential to inform recovery prognosis and treatment recommendations
