Measurement precision matters: Accounting for uncertainty alters estimated memory trajectories across the cognitive spectrum
Emily H. Trittschuh, Phoebe Scollard, Paul K. Crane, Seo‐Eun Choi, Jesse Mez, Andrew J. Saykin, Laura E. Gibbons, Shubhabrata MukherjeeAbstract
INTRODUCTION
Harmonized cognitive composites are widely used to study longitudinal cognitive decline. Although harmonization places scores on a common latent scale, measurement precision varies across visits, age, and diagnosis, but is typically ignored in longitudinal models.
METHODS
We analyzed harmonized memory scores and time‐varying standard errors from the National Alzheimer's Coordinating Center Uniform Data Set. We compared a naïve mixed‐effects model that did not incorporate measurement uncertainty with two precision‐aware models: a frequentist precision‐weighted and a Bayesian measurement‐error model. Comparisons were based on estimated age of memory impairment.
RESULTS
Accounting for measurement precision produced age‐dependent differences in estimated memory trajectories. Naïve models predicted higher memory scores at older ages in cognitively normal and mildly impaired participants but lower scores in Alzheimer's dementia (AD). Precision‐aware models estimated threshold crossing 1.5–3 years earlier than the naïve model.
DISCUSSION
Incorporating visit‐specific measurement precision alters estimated cognitive trajectories and the timing of clinically interpretable memory impairment.