Staging methods for the assessment of dementia: Perspectives.

Most dementias in old age are characterized by a progressive course with interindividual variability in pattern and rate of progression. Developing a system for staging such dementia poses a challenge in capturing this variability in a system that will afford comparisons among individuals and predictions of future change. Several core questions underlie the development of such systems: (1) Is there a definable order in which abilities are lost? (2) Which skills and functions should be considered essential for the staging of dementia and what is their relative weight? (3) Can the different skills be captured within one staging system? (4) How is the whole range of function captured, and are the differences between stages clearly defined? (5) Which populations can be rated with each staging system? The determination of this last question is based on understanding which other medical conditions may interfere with the course of dementia and how prior characteristics, such as education, affect ratings on specific scales for the staging of dementia. Several systems for staging dementia in older adults are described. These include the Clinical Dementia Rating, the Global Deterioration Scale/Brief Cognitive Rating Scale/Functional Assessment Staging System, the Six Clinical Phases of Cognitive Decline, the Hierarchic Dementia Scale, and the Functional Capacity Scale. Some aspects of the utility of these systems are reviewed, and the issues for further research are discussed.