The Relationship between Depression and Cognition in Older Adults: A Cross-validation Study

Abstract

The relationship between depression and cognition in older adults has become a topic of extensive research and clinical interest. Results of previous research are limited, however, by sampling and methodological problems. Small sample sizes and the treatment of depression as a dichotomous variable may be major factors that limit data interpretation in previous studies. The present sample of 220 geriatric medical patients was split into a validation and a cross-validation sample specifically to test the hypothesis that depression is an independent predictor of cognition. Multiple regression analyses, controlling for the direct effects of demographic factors, found that Geriatric Depression Scale scores were consistently a significant predictor of Dementia Rating Scale and Logical Memory scores. Overall, GDS scores accounted for approximately 8% of unique variance for both measures of cognition. Demographic factors, particularly age and race, were also significant predictors of cognitive test scores. These data were interpreted as providing support for the hypothesis that level of depression predicts level of cognitive functioning.

Early Detection and Differential Diagnosis of Alzheimer’s Disease and Depression with Neuropsychological Tasks

“…It is also important that patients without AD are not falsely 'detected' by such a test. One of the most difficult disorders to differentially diagnose from AD is depression, and contributing to this is the fact that some episodic memory tests which are very sensitive to AD -particularly 'effortful' tasks such as free recall -are also vulnerable in depression [25,26]. A range of cognitive functions other than episodic memory, including semantic memory (knowledge-or fact-based memory), attention and executive function (high-level control processes), is significantly impaired in the mild stages of AD [16,27,28], and indeed, tests of many different cognitive capacities have been shown to be predictive of future AD diagnosis among memory-impaired subjects [13,29].…”

Differential muscarinic and NMDA contributions to visuo-spatial paired-associate learning in rhesus monkeys

“…Improving the specificity of such tests is important in differentiating AD individuals from other populations who may perform poorly on neuropsychological tests. For example elderly subjects with major depression perform poorly on tests of memory that AD subjects perform poorly (Lichtenberg et al 1995;Zakzanis et al 1998). It would therefore be crucial to distinguish depressed individuals from AD individuals when proposing to use any risky or invasive treatment.…”

Memory Improvement in Assisted Living Elders

“…This fear is based on the reality that memory declines with age (Rinn, 1988). A complicating factor, however, in the relationship between perceived memory loss and actual memory performance is depression (Dellefield & McDougall,1996;Lichtenberg, Ross, Millis, & Manning, 1995;Nussbaum & Sauer, 1993). The confounding effects of depression have particular relevance for episodic remembering in very old adults (Backman, Hassing, Forsell, & Viitanen, 1996 Long-term care residents have major depressive disorders and depressive symptoms (McDougall, 1998b;Rovner et al, 1991).…”