Central executive system impairment in traumatic brain injury.

PRIMARY OBJECTIVE: This study investigated whether cognitive impairment after traumatic brain injury (TBI) can be considered a consequence of (1) a speed processing deficit or (2) an impairment of the Central Executive System (CES) of working memory. METHODS AND PROCEDURES: Thirty-seven TBI patients underwent a standardized battery of neuropsychological tests evaluating speed processing, sustained attention, short-term memory, working memory, divided attention, executive functions and long-term memory. MAIN OUTCOMES AND RESULTS: Patients showed severe deficits in working memory, divided attention, executive functions and long-term memory. Divided attention, long-term memory and executive functions deficits significantly correlated with working memory, but not with speed processing deficits. Moreover, multiple regression analyses showed that a CES impairment and not a speed processing deficit predicted divided attention, executive functions and long-term memory deficits. The severity and the site of brain lesions did not predict the level of CES or speed processing impairment. CONCLUSIONS: The cognitive impairment following TBI seem to be caused by an impairment of the Central Executive System, rather than a speed processing deficit.