Cognitive functioning ten years following traumatic brain injury and rehabilitation.

Many previous studies investigating long-term cognitive impairments following traumatic brain injury (TBI) have focused on extremely severely injured patients, relied on subjective reports of change and failed to use demographically relevant control data. The aim of this study was to investigate cognitive impairments 10 years following TBI and their association with injury severity. Sixty TBI and 43 control participants were assessed on tests of attention, processing speed, memory, and executive function. The TBI group demonstrated significant cognitive impairment on measures of processing speed (Symbol Digit Modalities Test [SDMT], Smith, 1973; Digit Symbol Coding, Wechsler, 1997), memory (Rey Auditory Verbal Learning Test [RAVLT]; Rey, 1958; Lezak, 1976), Doors and People tests; Baddeley, Emslie & Nimmo-Smith, 1994) and executive function (Hayling C [Burgess & Shallice, 1997] and SART errors, Robertson, Manly, Andrade, Baddeley & Yiend, 1997). Logistic Regression analyses indicated that the SDMT, Rey AVLT and Hayling C and SART errors most strongly differentiated the groups in the domains of attention/processing speed, memory and executive function, respectively. Greater injury severity was significantly correlated with poorer test performances across all domains. This study shows that cognitive impairments are present many years following TBI and are associated with injury severity.