Mayo normative studies: A conditional normative model for longitudinal change on the Auditory Verbal Learning Test and preliminary validation in preclinical Alzheimer's disease
Eva Alden, Emily S. Lundt, Erin Twohy, Teresa J. Christianson, Walter K. Kremers, Mary M. Machulda, Clifford R. Jack, David S. Knopman, Michelle M. Mielke, Ronald C. Petersen, Nikki H. Stricker
Abstract
Abstract Introduction The aim of this study was to develop a conditional normative model for Rey's Auditory Verbal Learning Test (AVLT) that accounts for practice effects. Methods In our normative sample, robust conditional norms were derived from 1001 cognitively unimpaired (CU) adults ages 50 to 89 who completed the AVLT up to eight times. Linear mixed‐effects models adjusted for baseline performance, prior test exposures, time, demographics, and interaction terms. In our preliminary validation, mean performance on conditional and typical normative scores across two to four completed follow‐up tests in preclinical Alzheimer's disease participants at baseline with positive amyloid and tau positron emission ( n = 27 CU amyloid [A]+tau[T]+) was compared to biomarker negative individuals ( n = 269 CU A–T–). Results AVLT performance using typical norms did not differ across A+T+ and A–T– groups. Conditional norms z‐scores were lower in the A+T+ relative to the A–T– group for 30‐minute recall ( P = .033) and sum of trials ( P = .030). Discussion Conditional normative methods that account for practice effects show promise for identifying longitudinal cognitive decline.