Flexible adaptation to changing task demands in severe closed head injury patients: a driving simulator study

The assessment of fitness to drive in patients with closed head injury (CHI) does not usually include executive functioning. Executive functions may be particularly important for the tactical (e.g. anticipatory adaptation of speed) and strategical (e.g. choice of route and time) aspects of driving. The literature lacks evidence on the tactical aspects, which are critical in the assessment of actual driving. Executive functioning was therefore assessed in a task context relevant to tactical decision making in driving. Twenty very severe chronic CHI patients and 20 healthy control subjects were tested with a driving simulator test and an extended neuropsychological test battery. In the driving simulator test, executive function was operationally defined as the flexible adaptation to changing task demands. A specific feature of the test was the experimental control for slow information processing, a persistent sequel of severe CHI. Given this control for slow information processing, it was found that patients were unimpaired in their flexible adaptations. Similar findings were obtained with a neuropsychological test battery. Patients were consistently slower, but planning and flexibility were found to be unimpaired.