Longitudinal Changes in P3 Event‐related Potential among Older Adults with Preclinical Alzheimer’s Disease: A 1‐year Follow‐Up

Abstract

AbstractBackgroundThe third positive peak of the event‐related potential (ERP P3) is understood to reflect neural resource utilization during working memory. We previously showed lower P3 ERP amplitude of the task effect in older adults with preclinical Alzheimer’s disease (AD). The aim of this study was to compare changes from baseline to 1‐year follow‐up in P3 ERP between older adults with and without preclinical AD.MethodCognitively normal, beta‐amyloid positive (CNAβ+, n = 14) participants and beta‐amyloid negative (CNAβ‐, n = 15) controls completed a working memory task (n‐back) with three levels of difficulty (0, 1, 2) at baseline and 1‐year follow‐up. ERP P3 peak amplitude and latency of the task effect (non‐target minus target) were extracted from continuous electroencephalography recording. The frontal midline channel Fz was identified a priori as the main channel of interest. Aβ accumulation was characterized with [18F] Florbetapir positron emission tomography scans. Independent t‐tests, Fisher’s Exact, or Mann‐Whitney U tests were employed to compare baseline characteristics between groups. Linear mixed models with random intercept were used to compare changes in P3 peak amplitude and latency. Group (CNAβ+ vs CNAβ‐), time (baseline, 1‐year), and n‐back (0, 1, 2) were entered as main effects. The main analysis of interest was the interaction between group and time.ResultBaseline age, sex, MOCA scores, and n‐back accuracy and response times did not differ (p>0.11) between CNAβ+ and CNAβ‐ groups [Table 1]. Additionally, no longitudinal changes in MOCA scores or n‐back performance were observed between groups (p>0.41). A significant group by time interaction effect in P3 peak amplitude at Fz was found between CNAβ+ and CNAβ‐ participants (p = 0.049). The P3 peak amplitude increased by 48% in CNAβ+ participants, whereas only a 19% increase was observed in CNAβ‐ participants.ConclusionThe ERP revealed significant changes over time in P3 amplitude for the CNAβ+ participants compared to the CNAβ‐ controls. The greater increase of CNAβ+ task effect amplitude likely represents a growing imbalance in task specific resource allocation. Further investigation of this phenomenon is warranted to evaluate neuronal activity of preclinical AD and the use of P3 ERP as a potential screening tool.