Year: 2019
Type: article
Abstract: Previous studies in the Arizona APOE ε4 Gene Does Study have shown differential effects of APOE ε4 status on delayed recall verbal memory trajectories in cognitively unimpaired (CU) older adults. Specifically, ε4 homozygotes (HMs) showed accelerating declines relative to ε4 heterozygotes (HTs) and non-carriers (NCs). However, very few studies have investigated the trajectory of verbal learning changes in CU older adults. The aim of this study was to determine if APOE ε4 status has differential effects on three complimentary indices of verbal learning from the auditory verbal learning test (AVLT) in CU older adults. Data from 545 CU older adults participating in a longitudinal imaging and cognition study were analyzed. APOE ε4 status breakdown was: HM = 73, HT = 158, NC = 314. Mean age at baseline was 60.0±7.4 years and the mean education level was 15.8±2.3 years. The average follow-up length was 10.0±5.8 years. Verbal learning measures included Total Learning (TL), Learning Over Trials (LOT), and Learning Slope (LS). Linear mixed effects models that adjusted for age, education, sex, and baseline scores were used to derive subject-based slopes that were compared between NCs, HTs, and HMs using a one-way ANOVA. Cohen's d was used to quantify the effect size for significant groupwise comparisons. At baseline, TL (p = 0.50), LOT (p = 0.81), and LS (p = 0.81) showed no significant APOE group differences. Subject-based slopes for TL showed significant differences (HM<HT, NC; both p<0.001; NC vs HM d = 0.63, NC vs HM d = 0.41. LOT was significantly different between HMs and NCs (NC>HM, p<0.001, d = 0.43) and LS showed no significant differences (p = 0.08). These results demonstrate APOE-dependent verbal learning differences in CU older adults. Greater decline among HMs on these indices suggests their utility in detecting subtle cognitive changes that may precede clinically manifest MCI/AD. These findings also suggest that cognitive changes beyond delayed recall are present in those at high risk of developing MCI/AD.
Source: Alzheimer s & Dementia
Language: English
Subfield: Psychiatry and Mental health
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2980964587