Survivors of childhood traumatic brain injury (TBI) often suffer negative long-term outcomes, including attention problems and cognitive deficits. Although severity of TBI is a major factor influencing outcomes, premorbid functioning also influences outcomes.
Poor premorbid functioning appears to exacerbate the effects of TBI, whereas good premorbid functioning helps to buffer the effects of TBI. This moderating effect of premorbid functioning was tested by Yeates et al. (2005), who compared 4-year outcomes for 41 children who suffered severe TBI, 41 children who suffered moderate TBI, and 50 children who suffered orthopedic injury (OI), all of whom were between 6 and 12 years old at the time of injury.
Premorbid functioning was assessed by administering the CBCL a week after the child’s injury. Severity of TBI was assessed using the Glasgow Coma Scale (GCS; Teasdale & Jennett, 1974). Four years post-injury, children in the severe TBI group had significantly higher scores on both the CBCL Attention Problems syndrome and the ADHD-IV Rating Scale (DuPaul, Power, Anastopolous, & Reid, 1998) than children in the moderate TBI and OI groups. In the severe TBI group, premorbid CBCL Attention Problems scores significantly moderated the effects of TBI on long-term attention problems, as measured by both the CBCL and the ADHD Rating Scale. For both the CBCL and the ADHD Rating Scale, hierarchical linear regression indicated that higher premorbid Attention Problems scores amplified the long-term risk for children with severe TBI compared to children with OI. This moderating effect was not found when comparing the moderate TBI group with the OI group. Clinically significant scores on the CBCL Attention Problems syndrome (T > 60) were obtained by 46% of the severe TBI group versus 26% of the OI group. This difference was magnified for children with clinically significant premorbid Attention Problems (82% for severe TBI vs. 42% for OI) but was attenuated for children with low premorbid Attention Problems scores (32% for severe TBI vs. 21% for OI). Children with severe TBI also obtained significantly lower scores than children with OI on several cognitive measures tapping auditory working memory, verbal fluency, verbal rule learning, cognitive flexibility, response speed, and focused attention.
Performance on all the cognitive tests was significantly associated with long-term CBCL Attention Problems scores in all groups, but premorbid Attention Problems scores did not moderate the effects of TBI on cognitive outcomes. The authors concluded that their findings illustrate the construct of reserve capacity, whereby the greater the level of premorbid problems indicated by CBCL Attention Problems scores, the greater the impact of severe TBI on long-term attentional difficulties.
Reference: Yeates, K.O., Armstrong, K., Janusz, J., Taylor, H.G., Wade, S., Stancin, T., et al. (2005). Long-term attention problems in children with traumatic brain injury. Journal of the American Academy of Child and Adolescent Psychiatry, 44, 574-584.