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. 2021;82(1):317-325.
doi: 10.3233/JAD-201304.

In Vivo Amyloid, Neurodegeneration, and Verbal Learning in Late Middle-Aged Hispanics

Mouna Tahmi  1 , Brady Rippon  1 , Priya Palta  1   2 , Greysi Sherwood  1 , Gabriela Hernandez  1 , Luisa Soto  1 , Fernando Ceballos  1 , Michelle Pardo  1 , Krystal Laing  3 , Kay Igwe  3 , Hengda He  4 , Jeanne A Teresi  5 , Herman Moreno  6 , Qolamreza Razlighi  7 , Adam M Brickman  3   8   9 , José A Luchsinger  1   2
Affiliations

In Vivo Amyloid, Neurodegeneration, and Verbal Learning in Late Middle-Aged Hispanics

Mouna Tahmi et al. J Alzheimers Dis. 2021.

Abstract

Background: The National Institute on Aging (NIA)/Alzheimer's Association (AA) 2018 framework conceptualizes Alzheimer's disease (AD) biologically. Evidence of brain amyloid by biomarkers defines AD pathologic change and the Alzheimer's continuum. The presence of tau or neurodegeneration in the absence of amyloid defines non-AD pathologic change.

Objective: To examine the relation of in vivo amyloid and neurodegeneration with verbal learning, one of the cognitive abilities affected early in AD, in late middle age.

Methods: This was a cross-sectional study of amyloid and neurodegeneration biomarkers in a community-based cohort of 350 late-middle aged Hispanics without dementia (mean age: 64.15±3.34; 72.0%women). Amyloid (A) was measured as global standardized uptake value ratio (SUVR) with 18F-Florbetaben positron emission tomography (PET). Neurodegeneration (N) was ascertained as cortical thickness (CT) in AD signature areas using brain magnetic resonance imaging. We examined A/N continuously, categorically, by A/N profiles, and profile categories. The amyloid threshold for positivity was defined using the K means method. The CT threshold was defined as 2 standard deviations below the mean CT. Verbal learning was ascertained using total recall and delayed recall in the Buschke Selective Reminding test (SRT).

Results: Higher cortical thickness was associated with higher performance in SRT delayed recall. Amyloid SUVR was not related to SRT performance. The low CT category was associated with lower performance in SRT delayed recall, while Amyloid categories were not related to any SRT score. The non-AD pathologic change group (A-N+) performed worse in SRT delayed recall compared to the Normal A/N profile group (A-N-).

Conclusion: In late middle-aged Hispanics without dementia, non-AD pathologic change, but not the Alzheimer's continuum, was related to verbal learning.

Keywords: A/T/(N); Hispanics; NIA-AA; amyloid; cognition; neurodegeneration.

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Conflict of interest statement

CONFLICT OF INTEREST/DISCLOSURES STATEMENT

JA Luchsinger receives a stipend from Wolters Kluwer, N.V. as Editor in Chief of the journal Alzheimer’s disease and Associated Disorders, and has served as a paid consultant to vTv therapeutics, Inc. and Recruitment Partners. AM Brickman is a scientific advisor to Regeneron Pharmaceuticals and Cognition Therapeutics and has equity in Mars Holding Ltd. The other authors have no interests to declare.

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