Cognitive recovery and predictors of functional outcome 1 year after traumatic brain injury.

Outcome studies on traumatic brain injury (TBI) have shown that functional status can be predicted by demographic, injury severity, and trauma-related factors. Concurrent cognitive functions as one of the determinants of functional outcome is less documented. This study evaluated the effects of concurrent neuropsychological measures on functional outcome 1 year after injury. Neuropsychological data, employment status, self-reported fatigue, and the Glasgow Outcome Scale-Extended (GOSE) were collected from 115 persons with TBI (ranging from mild to severe) at 3 and 12 months postinjury. Principal components analysis was conducted with the neuropsychological measures and three components emerged. Multiple regression analysis, controlling for demographic and injury severity related factors, was used to test the effects of cognitive components at 12 months on functional outcome (GOSE). One year after injury, 64% were categorized as "good recovery" and 36% as "moderate disability" according to GOSE. Good functional recovery depended on shorter duration of posttraumatic amnesia, less fatigue, absence of intracranial pathology, higher education, and better performance on cognitive measures. The predictive values of Verbal/Reasoning and Visual/Perception components are supported; each added significantly and improved prediction of functional outcome. The Memory/Speed component showed a near-significant relationship to outcome.