Prolonged cognitive dysfunction in survivors of critical illness.

A prospective study using neuropsychological testing explored cognitive performance, and specifically executive function, in survivors of critical illness during the first year of recovery. Fifty-one patients who had survived 3 days or more in the intensive care unit were studied approximately 3 months after discharge; 45 of them were studied again 6 months later. General health was assessed using the Short-Form 36. Cognitive and executive functions were measured using Raven's Progressive Matrices, the Hayling Sentence completion test and the Six-Element Test. Three months after discharge from intensive care, all eight domains of Short-Form 36 were impaired among survivors; by 9 months, four of the eight domains showed significant improvement. At 3 months, 35% of patients scored at or below a level equivalent to the lowest performing 5% of a normal population (i.e. the fifth percentile) on two or more tests of cognitive function; by 9 months only 4% of patients were impaired to this extent. Although cognitive performance improved with time, it remained below normal.