Cognitive distinctions between depression and early Alzheimer's disease in the elderly

Abstract

Background : Currently, there is a diagnostic dilemma in terms of discriminating the reversible cognitive problems associated with depression from the irreversible dementia associated with early or mild Alzheimer's disease (AD) in the elderly. Previous research has focused on contrasting memory functions in depression versus AD, and methodological limitations undermine the results of the few empirical studies that have compared the linguistic and attentional abilities of these two patient populations. Aims : The objective of the current study was to determine whether depression is associated with any unique form of deficit in language or attention, and consequently whether more comprehensive assessment of these cognitive abilities may help to distinguish depression from early AD in elderly populations. Methods & Procedures : Age-matched groups of elderly adults with depression, early AD, or no psychiatric or neurological problems completed a comprehensive battery of basic and complex attention, language, and memory tests. Outcomes & Results : Results indicated that of the various cognitive abilities examined, the attention abilities of the depressed group, in particular their attention performance latencies, were most compromised compared to the control group. Tests of complex attention functions, working and episodic memory, and high-level language comprehension and production were most useful at distinguishing the depressed and early AD groups. Conclusions : These findings suggest that use of a small subset of high-level cognitive tests may allow accurate discrimination of elderly patients with depression from those in the early stages of AD.