Early detection of isolated memory deficits in the elderly: the need for more sensitive neuropsychological tests.

NoBackground. Early detection of cognitive decline in the elderly is important because this may precede progression to Alzheimer's disease. The aim of this study was to see whether sensitive neuropsychological tests could identify pre-clinical cognitive deficits and to characterize the cognitive profile of a subgroup with poor memory. Methods. A neuropsychological test battery was administered to a community-dwelling sample of 155 elderly volunteers who were screened with CAMCOG at enrolment (mean age 74·7 years). The battery included tests of episodic memory, semantic and working memory, language and processing speed. Results. Episodic memory test z scores below 1 S.D. from the cohort mean identified 25 subjects with `non-robust¿ memory performance. This group was compared to the remaining `robust memory¿ group with a General Linear Model controlling for age, IQ, education and gender. Test performance was significantly different in all tests for episodic and semantic memory, but not in tests for working memory, processing speed and language. CANTAB paired associates learning and spatial recognition tests identified the highest percentages of those in the `non-robust memory¿ group. Processing speed partialled out the age effect on memory performance for the whole cohort, but the `non-robust memory¿ group's performance was not associated with age or processing speed. Conclusions. Sensitive neuropsychological tests can detect performance below the norm in elderly people whose performance on MMSE and CAMCOG tests is well within the normal range. Age-related decline in memory performance in a cohort of the elderly may be largely due to inclusion within the cohort of individuals with undetected pre-clinical Alzheimer's disease or isolated memory impairment

The Placing Test: Preliminary investigations of a quick and simple memory test designed to be sensitive to pre-dementia Alzheimer's disease but not normal ageing

NoThe medial temporal lobe (MTL) memory system is damaged early in Alzheimer's disease. Cognitive tests designed to help diagnose the disease must detect dysfunction in this system, but must also be insensitive to the cognitive slowing that characterizes normal ageing. On the assumption that the MTL system forms new memories by binding together the many informational aspects of events into units, The Placing Test was designed to index this function by measuring the ability to remember associations between faces and their locations. The influence of normal ageing was minimized by using procedures that compensate for the difficulties in learning and retrieval caused by the cognitive slowing of normal ageing. In two experiments The Placing Test was administered as part of a battery of neuropsychological tests to a group of healthy older people. In both studies, performance in The Placing Test correlated significantly with other measures of memory, but had weaker associations than standard memory measures with other types of cognitive function. The Placing Test appeared not to be biased by age, education or gender, although a larger sample is needed to verify this. A final study examined the performance of 16 patients with suspected Alzheimer's disease. These patients showed clear impairment in The Placing Test, with 81% scoring below the 5th percentile, despite the majority having normal MMSE scores. It is concluded that The Placing Test provides a quick, simple and sensitive measure of memory that has potential to be useful in routine diagnostic investigations for Alzheimer's disease

Depressive Symptoms Increase the Likelihood of Cognitive Impairment in Elderly People with Subclinical Alzheimer Pathology

NoThe objective of this study was to investigate whether the presence of depressive symptoms influences the clinical expression of Alzheimer's pathology. We have analysed the relationships between the severity of Alzheimer's pathology and cognitive decline in two patient groups defined by the presence or absence of depressive symptoms. The study included 89 subjects who participated in a longitudinal research programme prior to death, underwent post-mortem examination and were found to have only Alzheimer-type pathology in their brains, ranging in severity from the entorhinal to neocortical stages. Our results indicate that depressive symptoms did not influence cognition in the early (entorhinal) stages of Alzheimer's disease (AD; where cognition was good regardless of whether or not there was evidence for depressive symptoms) or in the late (neocortical) stages (where cognition was poor regardless of whether or not there was evidence for depression). However, in the intermediate (limbic) stages, patients with depressive symptoms had significantly worse cognitive performance (mean CAMCOG of 32) than those who did not (mean CAMCOG of 73). We conclude that depressive symptoms may contribute to the cognitive decline of AD patients in that pathology, that would be otherwise silent, becomes clinically apparent. Therefore, a multiple diagnosis of early AD and depression should be more widely considered in elderly persons presenting with mild cognitive decline and depression. Treating the depressive symptoms would benefit the patient, but the cognitive improvement may not indicate that AD is absent