Objective: To compare several clinical methods of following change in Alzheimer's disease (AD) over time.
Data sources: MEDLINE search (restricted to English language); bibliographies of pertinent articles or books.
Study selection: Studies included only if aim was to follow a cohort of AD patients; diagnosis of AD used DSM-III-R or NINCDS-ADRDA guidelines; techniques or scales used for serial assessment were well-established in terms of validity and reliability.
Data extraction: All 3 authors reviewed all studies cited and reached consensus about interpretation.
Results: Global instruments detect long term deterioration in AD and describe distinct through possibly artificial stages. Cognitive screening tests decline at a consistent rate for groups of AD patients but show considerable variability. Scales measuring activities of daily living (ADLs) need further study to determine annual rate of change. Instrumental ADLs decline early in AD and reach a floor before cognitive screening tests. Electrophysiologic or radiographic techniques do not necessarily change over time and are not superior to clinical methods for following AD. Variability in rate of cognitive change and prognosis in AD has not been adequately explained.
Conclusions: Cognitive screening tests provide useful measures of rate of change in AD for clinical and therapeutic studies. Further studies should take advantage of longer follow-up and more sophisticated statistical techniques to optimize use of these measures.