"Who am I if my Brain Has Changed?": Changes to Self-Identity after Severe Traumatic Brain Injury and the Relationship to Neurocognitive, Psychological and Social/Occupational Factors

Abstract

Traumatic brain injury (TBI) is a sudden, unexpected neurological event that can change an individual’s life course. Changes to self-identity or self-discrepancy between one’s pre-injury and post-injury selves is commonly reported. However, the mechanisms that underlie these subjectively experienced alterations after TBI are poorly understood. Comprised of four main studies, the broad objective of this thesis was to advance understanding of the impact of severe TBI on self-identity and the neurocognitive, psychological, and social/occupational factors associated with self-identity changes. Study 1 consists of a systematic review of research on the impact of TBI on self-identity and the associations between self-identity change and neurocognitive and psychosocial functioning. Searches of four databases revealed fifteen studies that quantitatively examined changes in self-identity after TBI in adults using measures of self-concept, personality, or self-discrepancy. Despite methodological differences, these studies consistently identified evidence of negative changes to self-concept. However, stability in self-concept and positive changes in personal attributes were also reported. Negative changes in self-concept were associated with greater emotional distress in three of the studies. Key areas for further investigation related to understanding how neurocognitive functioning, psychological characteristics, and occupational engagement contribute to self-identity changes after TBI. Guided by the findings of the systematic review, studies 2 to 4 used a validated measure of self-discrepancy (Head Injury Semantic Differential Scale [HISD] III) to examine the relationship between self-discrepancy and neurocognitive functions (study 2), psychological characteristics (study 3), and social/occupational factors (study 4). The participants were 59 adults with severe TBI (72.9% male, M age = 36.50 years, SD= 12.54) recruited as part of a broader cognitive rehabilitation study. Participants were administered neuropsychological tests and questionnaires in the home. Study 2 aimed to examine associations between self-discrepancy and measures of attention, memory, executive function, and self-awareness (i.e., Hopkins Verbal Learning Test, Trail Making Test, Zoo Map, Digit Span, Modified Stroop, Controlled Oral Word Association Test & Awareness Questionnaire). The results revealed that more negative self-discrepancy was significantly associated with better neurocognitive functions. Specifically, more negative self-discrepancy was associated with greater self-awareness and better performance on tests of immediate memory, working memory, and verbal fluency. Self-awareness was the only neurocognitive factor significantly and uniquely related to self-discrepancy, and was found to partially mediate the relationship between immediate memory and self-discrepancy. Overall, the findings highlighted that memory and self-awareness are central to updating self-identity after severe TBI. Study 3 aimed to examine the relationship between personality characteristics (optimism and defensiveness), cognitive appraisals (threat appraisals, rumination, reflection, and perceived coping resources) and self-discrepancy. These constructs were assessed using the Life Orientation Test, Marlow Crowne Social Desirability Scale – short form, Appraisal of Threat and Avoidance Questionnaire, Reflection and Rumination Questionnaire, Coping Resource Questionnaire and HISD-III. Correlation analyses revealed that higher levels of optimism, defensiveness, and perceived coping resources were significantly associated with more positive self-discrepancy, whereas higher threat appraisals and rumination were significantly associated with more negative self-discrepancy. After controlling for personality characteristics, cognitive appraisals significantly accounted for self-discrepancy. Rumination significantly mediated the relationship between optimism and self-discrepancy. Overall, these findings suggest that individuals with certain personality characteristics and associated cognitive appraisals are more likely to experience negative self-discrepancy after severe TBI. Study 4 examined the nature of occupational engagement after severe TBI, and the relationship between re-engagement in desired occupations, mood, psychosocial functioning and self-discrepancy. Participants with TBI completed the Occupational Gaps Questionnaire, Depression, Anxiety, and Stress Scales–21 and HISD-III and their relatives completed the Sydney Psychosocial Reintegration Scale. The results revealed that greater occupational re-engagement gaps were related to higher levels of anxiety and poorer psychosocial functioning. A mediation analysis revealed that re-engagement gaps were indirectly related to self-discrepancy through an association with anxiety. These results suggest that anxiety related to gaps in occupational functioning may contribute to negative comparisons between pre-injury and post-injury self. Overall, this thesis advances understanding of changes to self-identity after TBI. Specifically, study 1 demonstrated that negative self-discrepancy is most commonly experienced and highlighted the need to further understand the role of neurocognitive and psychosocial factors. Studies 2 to 4 showed that individuals with better memory function, lower optimism, and greater occupational gaps (indirectly) are more likely to experience negative self-discrepancy. These associations were mediated by self-awareness, rumination, and anxiety symptoms (respectively), which represent potential targets for intervention to facilitate positive identity change after TBI. Collectively, the findings highlight the importance of integrated rehabilitation approaches that simultaneously address neurocognitive impairments, psychological adjustment, and activity re-engagement after severe TBI.