Dual-task performance in Alzheimer's disease, mild cognitive impairment, and normal ageing.

Although several studies have shown that dual-tasking ability is impaired in Alzheimer's disease (AD), the stage at which this deficit manifests remains unclear. This study investigated if a new paper-and-pencil assessment of dual-tasking ability could distinguish between AD, mild cognitive impairment (MCI) and normal ageing in a sample of 50 people with AD, 49 people with MCI, and 50 healthy age-matched controls. The AD group demonstrated a significant impairment in dual-task ability. There was no effect of either MCI or healthy ageing on dual-task performance, indicating that the dual-task impairment is specific to AD.