Alzheimer’s disease (AD) is associated with a marked impairment in the ability to do two things at once, or ‘dual task’. Several studies have reported that depression is also associated with impairments in cognitive functioning, particularly executive functioning, but it remains unclear if depression also leads to impairments in dual tasking ability. Therefore, this paper describes two experiments, assessing (1) dual tasking ability in 50 people with AD and 50 healthy controls, and (2) dual tasking and planning ability, as assessed using the Tower of Hanoi task, in 24 people with depression and 21 healthy controls. The AD group showed marked impairment in dual tasking ability, but the depressed group showed impairment on the Tower of Hanoi task, but preserved performance on the measure of dual tasking. This shows that shows that whereas AD is associated with gross impairment in dual tasking ability, depression is associated with a patchy pattern of impairment across the different cognitive functions, but, importantly, preserved dual tasking ability.
