Superior Memory Reduces 8-year Risk of Mild Cognitive Impairment and Dementia But Not Amyloid Beta-Associated Cognitive Decline in Older Adults

Author: Dang, Christa; Harrington, Karra D.; Lim, Yen Ying; Ames, David; Hassenstab, Jason; Laws, Simon M.; Yassi, Nawaf; Hickey, Martha; Rainey-Smith, Stephanie R.; Robertson, Joanne; Rowe, Christopher C.; Sohrabi, Hamid R.; Salvado, Olivier; Weinborn, Michael; Villemagne, Victor L.; Masters, Colin L.; Maruff, Paul; AIBL Research Group

Description: OBJECTIVE: To prospectively examine 8-year risk of clinical disease progression to mild cognitive impairment (MCI)/dementia in older adults greater than or equal to 60 with superior episodic memory (SuperAgers) compared to those cognitively normal for their age (CNFA). Additionally, to determine the extent to which SuperAgers were resilient to the negative effects of elevated amyloid-beta (AB+) on cognition.

METHOD: Participants were classified as SuperAgers based on episodic memory performance consistent with younger adults aged 30-44 and no impairment on non-memory tests (n = 179), and were matched with CNFA on age, sex, education, and follow-up time (n = 179). Subdistribution hazard models examined risk of clinical progression to MCI/dementia. Linear mixed models assessed the effect of AB+ on cognition over time.

RESULTS: Prevalence of AB+ and APOE e4 was equivalent between SuperAgers and CNFA. SuperAgers had 69%-73% reduced risk of clinical progression to MCI/dementia compared to CNFA (HR: 0.27-0.31, 95% CI: 0.11-0.73, p<.001). AB+ was associated with cognitive decline in verbal memory and executive function, regardless of SuperAger/CNFA classification. In the absence of AB+, equivalent age-related changes in cognition were observed between SuperAgers and CNFA.

CONCLUSIONS: SuperAgers displayed resilience against clinical progression to MCI/dementia compared to CNFA despite equivalent risk for Alzheimer’s disease (AD); however, SuperAgers had no greater protection from AB+ than CNFA. The deleterious effects of AB on cognition persist regardless of baseline cognitive ability. Thus, superior cognitive performance does not reflect resistance against the neuropathological processes associated with AD, and the observed resilience for SuperAgers may instead reflect neuropsychological criteria for cognitive impairment.

Subject headings: Aged; Aged; 80 and over; Amyloid beta-Peptides; Attention; Cognition; Cognitive Dysfunction; Dementia; Disease Progression; Executive Function; Female; Humans; Male; Memory; Neuropsychological Tests; Alzheimer’s disease; Elderly/geriatrics/aging; Mild cognitive impairment

Publication year: 2019

Journal or book title: Archives of Clinical Neuropsychology: The Official Journal of the National Academy of Neuropsychologists

Volume: 34

Issue: 5

Pages: 585-598

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Serial number: 3172

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