- Harmonized cognitive composites mask varying measurement precision across visits, age, and diagnosis, which is typically ignored in longitudinal models.
- Study compared naïve mixed-effects model with two precision-aware approaches: frequentist precision-weighted and Bayesian measurement-error models using NACC harmonised memory scores.
- Precision-aware models changed age-dependent memory trajectories and estimated threshold crossing 1.5 to 3 years earlier than naïve models.
Alzheimers Dement. 2026 Nov;22(11):e71976. doi: 10.1002/alz.71976.
ABSTRACT
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.
PMID:42982742 | DOI:10.1002/alz.71976
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