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Association of β-Amyloid and Apolipoprotein E ε4 With Memory Decline in Preclinical Alzheimer Disease.
JAMA Neurol. 2018 04 01; 75(4):488-494.JN

Abstract

Importance

Older age, high levels of β-amyloid (Aβ), and the presence of the apolipoprotein E (APOE) ε4 allele are risk factors for Alzheimer disease (AD). However, the extent to which increasing age, Aβ, and ε4 are associated with memory decline remains unclear, and the age at which memory decline begins for Aβ-positive ε4 carriers and noncarriers has not been determined.

Objective

To determine the association of age, Aβ level, and APOE ε4 with memory decline in a large group of cognitively healthy older adults.

Design, Setting, and Participants

This longitudinal observational study included cognitively healthy older adults (age >60 years) enrolled in the Australian Imaging, Biomarkers and Lifestyle (AIBL) study from March 31, 2006, through March 31, 2017; of 1583 individuals enrolled, 1136 refused or were excluded owing to other criteria (eg, having mild cognitive impairment or AD). Participants underwent Aβ imaging in research clinics in Perth and Melbourne and more than 72 months of follow-up (at 18-month intervals). The association of age with memory was fitted to a quadratic model. Age was treated as a continuous, time-dependent variable.

Exposures

β-Amyloid imaging using positron emission tomography, genotyping for APOE ɛ4, and longitudinal neuropsychological assessments of episodic memory during the 72-month follow-up.

Main Outcomes and Measures

Episodic memory composite score.

Results

Of the 447 participants, 203 (45.4%) were men and 244 (54.6%) were women; mean (SD) age was 72.5 (6.6) years. Equal proportions of female participants were observed in each Aβ-ɛ4 group (24 of 51 Aβ-positive ε4 noncarriers [47.1%] ; 35 of 64 Aβ-negative ε4 carriers [54.7%]; 40 of 72 Aβ-positive ε4 carriers [55.6%]; and 145 of 260 Aβ-negative ε4 noncarriers [55.8%]). Adults with Aβ findings (mean [SD] age, 74.4 [6.8] years) were approximately 4 years older than those negative for Aβ (mean [SD] age, 69.8 [6.1] years). Memory decline diverged significantly from Aβ-negative ɛ4 noncarriers at an earlier age in Aβ-positive ɛ4 carriers (64.5 years) than in Aβ-positive ɛ4 noncarriers (76.5 years), such that by 85 years of age, Aβ-positive ε4 carriers performed approximately 1.5 SD units worse on the episodic memory composite than Aβ-negative ε4 noncarriers and approximately 0.8 SD units worse than Aβ-positive ε4 noncarriers. Memory performance of Aβ-negative ɛ4 carriers did not differ from that of the Aβ-negative ɛ4 noncarriers (estimate [SE], 0.001 [0.001]; t = 0.526; P = .77).

Conclusions and Relevance

Prior work has shown that Aβ and ε4 combine to influence memory decline in nondemented older adults. Results of this study indicate that increasing age may further exacerbate these effects. The estimates provided may be used to determine the risk of memory decline associated with Aβ and ε4 at each age.

Authors+Show Affiliations

The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia.CogState, Ltd, Melbourne, Victoria, Australia.Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut.Centre of Excellence for Alzheimer's Disease Research and Care, Edith Cowan University, Joondalup, Western Australia, Australia. Sir James McCusker Alzheimer's Disease Research Unit, Hollywood Private Hospital, Perth, Western Australia, Australia. Cooperative Research Centre for Mental Health, Carlton, Victoria, Australia.Commonwealth Scientific and Industrial Research Organisation Preventative Health National Research Flagship, Australian e-Health Research Centre, Brisbane, Queensland, Australia.Academic Unit for Psychiatry of Old Age, St Vincent's Health, University of Melbourne, Kew, Victoria, Australia. National Ageing Research Institute, Parkville, Victoria, Australia.The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia. Department of Nuclear Medicine and Centre for PET (Positron Emission Tomography), Austin Health, Heidelberg, Victoria, Australia. Department of Medicine, Austin Health, University of Melbourne, Heidelberg, Victoria, Australia.The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia.Centre of Excellence for Alzheimer's Disease Research and Care, Edith Cowan University, Joondalup, Western Australia, Australia.Centre of Excellence for Alzheimer's Disease Research and Care, Edith Cowan University, Joondalup, Western Australia, Australia.Department of Nuclear Medicine and Centre for PET (Positron Emission Tomography), Austin Health, Heidelberg, Victoria, Australia. Department of Medicine, Austin Health, University of Melbourne, Heidelberg, Victoria, Australia.The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia.The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia. CogState, Ltd, Melbourne, Victoria, Australia.

Pub Type(s)

Journal Article
Observational Study
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

29356823

Citation

Lim, Yen Ying, et al. "Association of β-Amyloid and Apolipoprotein E Ε4 With Memory Decline in Preclinical Alzheimer Disease." JAMA Neurology, vol. 75, no. 4, 2018, pp. 488-494.
Lim YY, Kalinowski P, Pietrzak RH, et al. Association of β-Amyloid and Apolipoprotein E ε4 With Memory Decline in Preclinical Alzheimer Disease. JAMA Neurol. 2018;75(4):488-494.
Lim, Y. Y., Kalinowski, P., Pietrzak, R. H., Laws, S. M., Burnham, S. C., Ames, D., Villemagne, V. L., Fowler, C. J., Rainey-Smith, S. R., Martins, R. N., Rowe, C. C., Masters, C. L., & Maruff, P. T. (2018). Association of β-Amyloid and Apolipoprotein E ε4 With Memory Decline in Preclinical Alzheimer Disease. JAMA Neurology, 75(4), 488-494. https://doi.org/10.1001/jamaneurol.2017.4325
Lim YY, et al. Association of β-Amyloid and Apolipoprotein E Ε4 With Memory Decline in Preclinical Alzheimer Disease. JAMA Neurol. 2018 04 1;75(4):488-494. PubMed PMID: 29356823.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Association of β-Amyloid and Apolipoprotein E ε4 With Memory Decline in Preclinical Alzheimer Disease. AU - Lim,Yen Ying, AU - Kalinowski,Pawel, AU - Pietrzak,Robert H, AU - Laws,Simon M, AU - Burnham,Samantha C, AU - Ames,David, AU - Villemagne,Victor L, AU - Fowler,Christopher J, AU - Rainey-Smith,Stephanie R, AU - Martins,Ralph N, AU - Rowe,Christopher C, AU - Masters,Colin L, AU - Maruff,Paul T, PY - 2018/1/23/pubmed PY - 2019/9/11/medline PY - 2018/1/23/entrez SP - 488 EP - 494 JF - JAMA neurology JO - JAMA Neurol VL - 75 IS - 4 N2 - Importance: Older age, high levels of β-amyloid (Aβ), and the presence of the apolipoprotein E (APOE) ε4 allele are risk factors for Alzheimer disease (AD). However, the extent to which increasing age, Aβ, and ε4 are associated with memory decline remains unclear, and the age at which memory decline begins for Aβ-positive ε4 carriers and noncarriers has not been determined. Objective: To determine the association of age, Aβ level, and APOE ε4 with memory decline in a large group of cognitively healthy older adults. Design, Setting, and Participants: This longitudinal observational study included cognitively healthy older adults (age >60 years) enrolled in the Australian Imaging, Biomarkers and Lifestyle (AIBL) study from March 31, 2006, through March 31, 2017; of 1583 individuals enrolled, 1136 refused or were excluded owing to other criteria (eg, having mild cognitive impairment or AD). Participants underwent Aβ imaging in research clinics in Perth and Melbourne and more than 72 months of follow-up (at 18-month intervals). The association of age with memory was fitted to a quadratic model. Age was treated as a continuous, time-dependent variable. Exposures: β-Amyloid imaging using positron emission tomography, genotyping for APOE ɛ4, and longitudinal neuropsychological assessments of episodic memory during the 72-month follow-up. Main Outcomes and Measures: Episodic memory composite score. Results: Of the 447 participants, 203 (45.4%) were men and 244 (54.6%) were women; mean (SD) age was 72.5 (6.6) years. Equal proportions of female participants were observed in each Aβ-ɛ4 group (24 of 51 Aβ-positive ε4 noncarriers [47.1%] ; 35 of 64 Aβ-negative ε4 carriers [54.7%]; 40 of 72 Aβ-positive ε4 carriers [55.6%]; and 145 of 260 Aβ-negative ε4 noncarriers [55.8%]). Adults with Aβ findings (mean [SD] age, 74.4 [6.8] years) were approximately 4 years older than those negative for Aβ (mean [SD] age, 69.8 [6.1] years). Memory decline diverged significantly from Aβ-negative ɛ4 noncarriers at an earlier age in Aβ-positive ɛ4 carriers (64.5 years) than in Aβ-positive ɛ4 noncarriers (76.5 years), such that by 85 years of age, Aβ-positive ε4 carriers performed approximately 1.5 SD units worse on the episodic memory composite than Aβ-negative ε4 noncarriers and approximately 0.8 SD units worse than Aβ-positive ε4 noncarriers. Memory performance of Aβ-negative ɛ4 carriers did not differ from that of the Aβ-negative ɛ4 noncarriers (estimate [SE], 0.001 [0.001]; t = 0.526; P = .77). Conclusions and Relevance: Prior work has shown that Aβ and ε4 combine to influence memory decline in nondemented older adults. Results of this study indicate that increasing age may further exacerbate these effects. The estimates provided may be used to determine the risk of memory decline associated with Aβ and ε4 at each age. SN - 2168-6157 UR - https://www.unboundmedicine.com/medline/citation/29356823/Association_of_β_Amyloid_and_Apolipoprotein_E_ε4_With_Memory_Decline_in_Preclinical_Alzheimer_Disease_ L2 - https://jamanetwork.com/journals/jamaneurology/fullarticle/10.1001/jamaneurol.2017.4325 DB - PRIME DP - Unbound Medicine ER -