Cognitive functioning following traumatic brain injury: The first 5 years.

OBJECTIVE: This study reports the results from a 5-year longitudinal investigation of the prevalence and severity of cognitive deficits following significant (i.e., ventilation required for > 24 hours) traumatic brain injury. The changes in performance, either improvement or decline, across five domains of cognitive functioning are described.

METHOD: A group of 56 adults was assessed at approximately 6 months, 1 year, and 5 years following injury.

RESULTS: Impairment was evident on all measures but prevalence and rate of improvement varied. Overall, by 5 years post-injury over 85% of patients were not impaired on measures of general intelligence, simple attention, and visual perception. However, 28% of patients continued to show some degree of impairment on complex attention and verbal fluency, and performance on verbal memory remained impaired for 60% of patients. There was also evidence for deterioration in complex attention and verbal memory between 1 year and 5 years. ANOVAs showed that improvement occurred on most measures between 6 months and 1 year, but there was both improvement and decline on some measures between 1 year and 5 years.

CONCLUSIONS: The findings show that there is considerable heterogeneity in cognitive outcome following TBI, with some deterioration evident over the long term.