Early Detection of Amyloid‐Related Changes in Memory among Cognitively Unimpaired Older Adults with Daily Digital Testing

Objective This study was undertaken to determine whether assessing learning over days reveals Alzheimer disease (AD) biomarker‐related declines in memory consolidation that are otherwise undetectable with single time point assessments. Methods Thirty‐six (21.9%) cognitively unimpaired older adults (aged 60–91 years) were classified with elevated β‐amyloid (Aβ+) and 128 (78%) were Aβ− using positron emission tomography with 11CPittsburgh compound B. Participants completed the multiday Boston Remote Assessment for Neurocognitive Health (BRANCH) for 12 min/day on personal devices (ie, smartphones, laptops), which captures the trajectory of daily learning of the same content on 3 repeated tests (Digit Signs, Groceries‐Prices, Face‐Name). Learning is computed as a composite of accuracy across all 3 measures. Participants also completed standard in‐clinic cognitive tests as part of the Preclinical Alzheimer's Cognitive Composite (PACC‐5), with 123 participants undergoing PACC‐5 follow‐up after 1.07 (standard deviation = 0.25) years. Results At the cross‐section, there were no statistically significant differences in performance between Aβ+/− participants on any standard in‐clinic cognitive tests (eg, PACC‐5) or on day 1 of multiday BRANCH. Aβ+ participants exhibited diminished 7‐day learning curves on multiday BRANCH after 4 days of testing relative to Aβ− participants (Cohen d = 0.49, 95% confidence interval = 0.10–0.87). Diminished learning curves were associated with greater annual PACC‐5 decline (r = 0.54, p