Dual task performance after severe diffuse traumatic brain injury or vascular prefrontal damage

The ability to perform two tasks simultaneously is a key function of the ce ntral executive of working memory (Baddeley, 1986). This study addressed du al-task performance after diffuse very severe traumatic brain injury (TBI) (mean coma duration = 21 days, mean post-traumatic amnesia = 70 days) or pr efrontal damage due to a ruptured aneurysm of the anterior communicating ar tery (AACA). Mean time since injury was 8 and 16 months in the TBI and the AACA group respectively. A simple visual reaction time and random number ge neration were used as single and dual tasks. Randomization was self-paced, to control for individual differences in speed. Both patient groups had gre ater reaction time decrements than controls under the dual-task condition, suggesting a divided attention deficit. In addition, patients with AACA per formed significantly poorer in random generation. These results suggest tha t patients with AACA and with severe TBI suffer from an impairment of the c entral executive system.