Chronic stress, cortisol regulation, interpersonal relatedness, cognitive burden, and depressive symptoms among community -dwelling survivors of brain injury.

Depression after traumatic brain injury is one of the most common and problematic mood disorders, affecting more than a third of those in the recovery process. Efforts to empirically examine this topic have failed to elucidate theoretical explanations and mechanisms. As part of the theory building process this study, using regression analysis, provided a cross-sectional examination of how major concepts, chronic stress, cortisol regulation, interpersonal relatedness and cognitive burden, which were derived from nursing and other disciplines could be related to post-brain injury depression. These concepts were empirically rooted in studies of depression. Thus, hypotheses were stated which posited explanatory relationships between depressive symptoms and these concepts. Seventy-five participants and their significant others were recruited from outpatient rehabilitation clinics. All had sustained a mild-to-moderate brain injury and were within two years of the trauma. Participants with TBI were asked to complete a computerized battery of cognitive tests on short-term memory and directed attention, provide a 12-hour profile of salivary cortisol and complete self-report questionnaires. Relative versions of the depression instruments were also completed. Overall, it was determined that when time-since-injury was included in regression models, pre- and post-injury stress explained a significant amount of the variability in depressive symptoms. Furthermore, a lowered sense-of-belonging, not social support, was a strong correlate of depressive symptoms. As in other studies, cognitive test results failed to provide clarity about the relationship between depressed mood and cognition. Post-injury stress and belonging account for nearly 75% of the variability of depressive symptoms. Cortisol regulation, determined by a 12-hour salivary cortisol profile of 50 of these participants, displayed circadian rhythm variation but demonstrated a lack of association with measures of cognition, head injury indices, depressive symptoms and post-injury stress. This study provides a foundation for further study of TBI and depression. Longitudinal studies, including pre-injury variables such as childhood adversities and the frequency of major stressful life events require further examination to develop knowledge regarding TBI and eventual nursing interventions.PhDHealth and Environmental SciencesNursingPhysical therapyPsychobiologyPsychologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/127111/2/3029291.pd