Life After Traumatic Brain Injury Cognitive, emotional and behavioural function after moderate and severe traumatic brain injury

Abstract

Traumatic brain injury (TBI) may occur after motor vehicle accidents, falls, or blows to the head. TBI may be classified as mild, moderate or severe depending on a number of factors, but primarily by level of consciousness after the trauma. Survivors after moderate and severe TBI comprise a heterogeneous group with great variability in terms of reduced function. They often experience impairments across a range of cognitive abilities, some of which may become chronic. In addition, secondary symptoms of emotional and behavioural problems may develop over time after the injury. Furthermore, all of these problems may affect the ability to resume work and engage in social activities; they may also affect the relationship to family and friends. There are few prospective studies examining cognitive, emotional, and behavioural function over a significant period of time. In addition, prospective studies on predictors of and associates to long-term cognitive, emotional, and behavioural function are still warranted. The main objective was to describe cognitive, emotional, and behavioural problems at several time points after TBI with emphasis on the long-term perspective. In addition, we wished to explore a broad array of demographic and injury-related factors hypothesized to be associated with cognitive, emotional, and behavioural outcomes after TBI. The study includes patients admitted to St. Olav’s Hospital, Trondheim University Hospital with moderate and severe TBI, from acute care to 5 years post-injury. It is part of a larger project, “The Head Injury Project”, which studies several aspects of the assessment, treatment, and clinical management of patients with TBI. The participants in the present study were recruited from the database of the “Head Injury Project”. Two overlapping but not identical populations (injured 2004-2007) and one extended population (injured 2004-2008) were included. Injury severity and level of consciousness were monitored and registered for all participants, and examination with MRI was performed within 4 weeks post-injury. At 3 months (n=61) and 12 months (n=50) post-injury, participants aged 15-65 years at the time of injury were assessed with neuropsychological tests and completed a questionnaire reporting symptoms of depression. The extended population (n=67) completed questionnaires concerning cognitive, emotional, and behavioural function 2-5 years post-injury. The results were compared with those of a control group consisting of healthy people matched by age, gender, and education. Our study demonstrated that differentiating between individuals with moderate and severe TBI revealed important differences regarding which cognitive functions were affected and the degree of cognitive impairment at 3 and 12 months post-injury; it also yielded a more nuanced description of cognitive deficits and their improvement over time. Cognitive function was affected by both moderate and severe TBI at 3 and 12 months post-injury, and was associated with global outcome 12 months postinjury. The groups differed regarding which cognitive functions improved from 3 to 12 months post-injury; only processing speed and visual memory improved for both groups. At 12 months post-injury, individuals with severe TBI exhibited reduced motor function, processing speed, verbal memory, and executive function. However, only executive function was reduced among patients with moderate TBI compared with healthy controls. Nevertheless, a larger proportion of individuals with moderate TBI had low scores (-1.5 SD below normative average) on tests that assessed executive function and processing speed at 12 months post-injury. Still, a significant proportion of individuals with moderate TBI exhibited normal performance on most neuropsychological tests at both 3 and 12 months post-injury – a finding that lends strength to previously raised concerns that cognitive problems after moderate TBI may be overestimated. Furthermore, executive function appears to be important for patients’ ability to resume independent living, employment, and leisure activities regardless of injury severity. Persons with moderate and severe TBI reported more pronounced difficulties in aspects of executive functions related to attentional control, working memory and emotional regulation, as well as emotional and behavioural problems related to symptoms of depression, anxiety, and aggression 2-5 years post injury compared to healthy controls. Reported symptoms of depression during the first year after injury and detection of traumatic diffuse axonal injury (DAI) on early MRI were important predictors of later self-reported executive, emotional, and behavioural problems. Our findings indicate interplay between demographic, neuropathological, and psychological factors during the development of self-reported executive, emotional, and behavioural problems for years after TBI. As such, outcomes after moderate and severe TBI are best understood within the frame of a biopsychosocial model. Hence, early radiological examination and repeated psychological evaluations screening for cognitive and emotional problems may provide clues to which patients may be at risk, and assist with the making of clinical decisions regarding long-term follow-up.