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Open Access Highly Accessed Research

Predicting progression of Alzheimer's disease

Rachelle S Doody1*, Valory Pavlik12, Paul Massman13, Susan Rountree1, Eveleen Darby1 and Wenyaw Chan4

Author Affiliations

1 Alzheimer's Disease and Memory Disorders Center, Baylor College of Medicine, 6501 Fannin Street, NB302, Houston, TX 77030, USA

2 Division of Family Medicine, Baylor College of Medicine, 3701 Kirby Drive, Houston, TX 77098, USA

3 Department of Psychology, University of Houston, 126 Heyne Building, Houston, TX 77204-5022, USA

4 Department of Epidemiology and Biostatistics, University of Texas Health Sciences Center, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA

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Alzheimer's Research & Therapy 2010, 2:2  doi:10.1186/alzrt25

Published: 23 February 2010

Abstract

Introduction

Clinicians need to predict prognosis of Alzheimer's disease (AD), and researchers need models of progression to develop biomarkers and clinical trials designs. We tested a calculated initial progression rate to see whether it predicted performance on cognition, function and behavior over time, and to see whether it predicted survival.

Methods

We used standardized approaches to assess baseline characteristics and to estimate disease duration, and calculated the initial (pre-progression) rate in 597 AD patients followed for up to 15 years. We designated slow, intermediate and rapidly progressing groups. Using mixed effects regression analysis, we examined the predictive value of a pre-progression group for longitudinal performance on standardized measures. We used Cox survival analysis to compare survival time by progression group.

Results

Patients in the slow and intermediate groups maintained better performance on the cognitive (ADAScog and VSAT), global (CDR-SB) and complex activities of daily living measures (IADL) (P values < 0.001 slow versus fast; P values < 0.003 to 0.03 intermediate versus fast). Interaction terms indicated that slopes of ADAScog and PSMS change for the slow group were smaller than for the fast group, and that rates of change on the ADAScog were also slower for the intermediate group, but that CDR-SB rates increased in this group relative to the fast group. Slow progressors survived longer than fast progressors (P = 0.024).

Conclusions

A simple, calculated progression rate at the initial visit gives reliable information regarding performance over time on cognition, global performance and activities of daily living. The slowest progression group also survives longer. This baseline measure should be considered in the design of long duration Alzheimer's disease clinical trials.