The Placing Test: Preliminary Investigations of a Quick and Simple Memory Test Designed to be Sensitive to Pre-dementia Alzheimer's Disease but not to Normal Ageing

Abstract

The 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. Elizabeth Anderson's work was supported by a Wellcome Trust Prize Studentship. All the staff at the OPTIMA project have provided considerable help and support during the course of this work. We would also like to thank the OPTIMA controls and patients who agreed to give up additional time to take part in this research. Dr. Julia Hornak very kindly provided photographs for the Missing Objects test. Thanks are also due to Anne Baker for her help in recruiting the additional subjects required for Study 1b from the Department of Experimental Psychology, Oxford University.