THE MEASUREMENT OF INCAPACITY IN THE SEVERELY DEMENTED ELDERLY - THE VALIDATION OF A BEHAVIORAL-ASSESSMENT SCALE

The development and validation of a scale for the assessment of intellectual functioning and adaptive behaviour in the severely dementing elderly (ECA) is described. This scale consists of items relating to the ‘survival roles’ proposed by the World Health Organization (physical independence, mobility, social integration, and language, occupation and orientation) and may be completed by non‐professional observers. The scale has highly acceptable interrater and internal reliability and is able to differentiate different levels of dementia. Moreover, ECA is able to describe the wide individual variation in individual functioning which is evident to the clinician but cannot be appreciated by standard cognitive tests, which have a ‘floor effect’ in severely demented populations. ECA scores correlate highly with both the Mini‐Mental State Examination and Psychometric assessment of agnosia, visual retention, verbal fluency, object naming and receptive language. A linear regression model is used to demonstrate the independence of ECA scores from age, education, associated pathology and perceptual handicap. The potential usefulness of the scale for both clinical and epidemiological studies is discussed. Copyright © 1991 John Wiley & Sons, Ltd.