Reduced awareness of cognitive decline is associated with brain amyloid load in asymptomatic elderly individuals at risk for AD: A longitudinal study

Abstract

AbstractBackgroundIt has recently been proposed that the awareness of cognitive decline (ACD) may already be slightly reduced in the preclinical phase of AD, in the presence of subtle cognitive changes. This is a recent field of research, and the few studies available do not allow to appreciate the actual evolution of ACD in the pre‐dementia phases of AD. The present study describes the longitudinal trajectory of an index of ACD (ACDI) over 3 years in a cohort of cognitively‐normal elderly, its association to AD biomarkers, as well as its impact on cognitive scores’ evolution.Method314 elderly memory complainers, as just as many study‐partners, were followed‐up for 3 years. Brain glucose metabolism and amyloid load were assessed at baseline; screening cognitive tests were performed every 6 months, and a comprehensive neuropsychological evaluation every 12 months. The ACDI was based on the subject‐informant discrepancy on a questionnaire evaluating the subject’s cognitive decline. We performed a Latent Class Linear Mixed Model (LCLMM) to identify different trends of evolution of the ACDI over time, and Generalized Linear Mixed Models to analyse the impact of the baseline ACDI on the evolution of cognitive scores.ResultThe LCLMM identified three classes of subjects sharing similar longitudinal trajectories of the ACDI. Most subjects (76.8%) have accurate ACD (Class 2), and have been considered as the reference group. 18.95% of subjects showed heightened ACD (“worried‐well” individuals). They were comparable to subjects with accurate ACD in terms of AD biomarkers. 4.25% of the sample showing low ACD had higher amyloid burden than the reference group, and were mostly men. The GLMM found no overall effect of baseline ACDI on the evolution of the cognitive scores.ConclusionThe study of ACD in AD, its evolution and correlates is a topic of growing interest, as it is, notably, a piece of the larger understanding of the pre‐dementia phases of AD. This can be useful for a timely diagnosis of AD, and for the selection of populations to be included in clinical trials.