Amyloid β-associated cognitive decline in the absence of clinical disease progression and systemic illness

Karra D Harrington; Yen Ying Lim; David Ames; Jason Hassenstab; Simon M Laws; Ralph N Martins; Stephanie Rainey-Smith; Joanne Robertson; Christopher C Rowe; Olivier Salvado; Vincent Doré; Victor L Villemagne; Peter J Snyder; Colin L Masters; Paul Maruff

doi:10.1016/j.dadm.2017.05.006

Amyloid β-associated cognitive decline in the absence of clinical disease progression and systemic illness

Alzheimers Dement (Amst). 2017 Jun 9:8:156-164. doi: 10.1016/j.dadm.2017.05.006. eCollection 2017.

Authors

Karra D Harrington^{1

2}, Yen Ying Lim^{1

3}, David Ames^{4

5}, Jason Hassenstab^{6

7

8}, Simon M Laws^{2

9

10}, Ralph N Martins^{9

11}, Stephanie Rainey-Smith^{9

11}, Joanne Robertson¹, Christopher C Rowe^{12

13}, Olivier Salvado¹⁴, Vincent Doré^{12

14}, Victor L Villemagne^{1

12

13}, Peter J Snyder^{15

16}, Colin L Masters¹, Paul Maruff^{1

3}

Affiliations

¹ The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia.
² Cooperative Research Centre for Mental Health, Parkville, Victoria, Australia.
³ CogState Ltd., Melbourne, Victoria, Australia.
⁴ Academic Unit for Psychiatry of Old Age, Department of Psychiatry, The University of Melbourne, Parkville, Victoria, Australia.
⁵ National Ageing Research Institute, Parkville, Victoria, Australia.
⁶ Charles F. and Joanne Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA.
⁷ Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA.
⁸ Department of Psychological & Brain Sciences, Washington University, St. Louis, MO, USA.
⁹ Centre of Excellence for Alzheimer's Disease Research and Care, School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia.
¹⁰ School of Biomedical Sciences, Faculty of Health Sciences, Curtin Health Innovation Research Institute, Curtin University, Western Australia, Australia.
¹¹ Sir James McCusker Alzheimer's Disease Research Unit, Hollywood Private Hospital, Perth, Western Australia, Australia.
¹² Department of Molecular Imaging, Austin Health, Melbourne, Victoria, Australia.
¹³ Department of Medicine, Austin Health, The University of Melbourne, Melbourne, Victoria, Australia.
¹⁴ CSIRO Health and Biosecurity, The Australian eHealth Research Centre, Brisbane, Queensland, Australia.
¹⁵ Department of Neurology, Warren Alpert School of Medicine, Brown University, Providence, RI, USA.
¹⁶ Department of Neurology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, USA.

Abstract

Introduction: High levels of amyloid β (Aβ) are associated with cognitive decline in cognitively normal (CN) older adults. This study investigated the nature of cognitive decline in healthy individuals who did not progress to mild cognitive impairment or dementia.

Method: Cognition was measured over 72 months and compared between low (Aβ-) and high (Aβ+) CN older adults (n = 335) who did not progress to mild cognitive impairment or dementia and who remained free of severe or uncontrolled systemic illness.

Results: Compared to the Aβ- group, the Aβ+ group showed no cognitive impairment at baseline but showed substantial decline in verbal learning, episodic memory, and attention over 72 months.

Discussion: Moderate cognitive decline, particularly for learning and memory, was associated with Aβ+ in CN older adults in the absence of clinical disease progression and uncontrolled or serious comorbid illness.

Keywords: Alzheimer disease; Amyloid; Cognitive aging; Memory; Normal aging.