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About the Authors:
Wei Liu
Affiliation: Department of Mathematics, Harbin Institute of Technology, Harbin, P.R. China
Bo Zhang
* E-mail: [email protected]
Affiliation: Biostatistics Core, School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon, United States of America
Zhiwei Zhang
Affiliation: Division of Biostatistics, Office of Surveillance and Biometrics, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, Maryland, United States of America
Xiao-Hua Zhou
Affiliation: Department of Biostatistics, School of Public Health and Community Medicine, University of Washington, HSR&D Center of Excellence, U.S. Department of Veterans Affairs Puget Sound Health Care System, Seattle, Washington, United States of America
Introduction
Alzheimer's disease is the most common type of dementia with the loss of brain function, which affects mental processes including attention, memory, producing and understanding language, learning, reasoning, problem solving, and decision making. Patients with Alzheimer's disease often are 65 years old or older, but there have been cases of early onset Alzheimer's (diagnosed before the age of 65) [1]. Usually, symptoms of Alzheimer's disease develop gradually and get worse as the disease progresses, and eventually lead to death. Currently, there are no clinical treatments that can cure Alzheimer's disease or reverse its progression, although the safety and efficacy of more than 400 pharmaceutical treatments have been or are being investigated worldwide (approximately a quarter of these compounds are in Phase III trials). According to Alzheimer's Association, 5.4 million Americans lived with Alzheimer's disease in 2012, and the disease is now the 6th leading cause of death in the United States [2]. In this research article, we consider the Uniform Data Set from the Alzheimer's Disease Centers program established by the National Institute on Aging (NIA) [3], [4]. The Alzheimer's Disease Centers program (U.S. National Institutes of Health Grant U01 AG016976) aims at characterizing individuals with mild Alzheimer's disease and cognitive impairment in comparison with nondemented aging. Currently more than 29 Alzheimer Disease Centers are funded to collect demographic, behavioral status, cognitive testing, and clinical diagnoses information on participants. In all Alzheimer Disease Centers, the data in Uniform Data Set are obtained longitudinally in a uniform manner from participants, using standard methods and uniform diagnostic criteria to evaluate subjects. The data are then...