Delayed primacy recall performance predicts Alzheimer's disease pathology from unimpaired cognitive baseline.

Introduction: We propose a novel method to assess delayed primacy in the CERAD memory test. We then examine whether this measure predicts Alzheimer's disease (AD) neuropathology in individuals who were clinically unimpaired at baseline.

Methods: A total of 1096 individuals were selected from the Rush Alzheimer's Disease Center database registry. All participants were clinically unimpaired at baseline, and had subsequently undergone brain autopsy. Average age at baseline was 78.8 (6.92). A Bayesian regression analysis was carried out with global pathology as outcome; demographic, clinical and data as covariates; and cognitive predictors, including delayed primacy.

Results: Global AD pathology was best predicted by delayed primacy. Secondary analyses showed that delayed primacy was mostly associated with neuritic plaques, whereas total delayed recall was associated with neurofibrillary tangles.

Discussion: We conclude that CERAD-derived delayed primacy is a useful metric for early detection and diagnosis of AD in unimpaired individuals.