Dual Task Performance in early Alzheimer's disease, amnestic mild cognitive impairment and depression

Abstract

Background: The dual task paradigm (Baddeley et al., 1986; Della Sala et al., 1995) has been proposed as a sensitive measure of Alzheimer’s disease, early in the disease process. Methods: We investigated this claim by administering the modified dual task paradigm (utilising a pencil and paper version of a tracking task) to 38 patients with amnestic Mild Cognitive Impairment (aMCI) and 10 with early Alzheimer’s disease, as well as 21 healthy elderly subjects and 17 controls with depressive symptoms. All groups were closely matched for age and pre-morbid intellectual ability. Results: There were no group differences in dual task performance, despite poor performance in episodic memory tests of the aMCI and early Alzheimer’s disease groups. In contrast, early Alzheimer’s disease and depressed patients were impaired in Part B of Trail Making Test, another commonly used measure of divided attention. Conclusions: The dual task paradigm lacks sensitivity for use in the early differential diagnosis of Alzheimer’s disease.