Reliability of P3 Event-Related Potential During Working Memory Across the Spectrum of Cognitive Aging

Abstract

Event-related potentials (ERPs) offer unparalleled temporal resolution in tracing distinct electrophysiological processes related to normal and pathological cognitive aging. The stability of ERPs in older individuals with a vast range of cognitive ability has not been established. In this test-retest reliability study, 39 older individuals (age 74.10 (5.4) years; 23 (59%) women; 15 non β-amyloid elevated, 16 β-amyloid elevated, 8 cognitively impaired) with scores on the Montreal Cognitive Assessment (MOCA) ranging between 3 and 30 completed a working memory (n-back) test with three levels of difficulty at baseline and 2-week follow-up. The main aim was to evaluate stability of the ERP on grand averaged task effects for both visits in the total sample (n = 39). Secondary aims were to evaluate the effect of age, group (non β-amyloid elevated; β-amyloid elevated, cognitively impaired), cognitive status (MOCA), and task difficulty on ERP reliability. P3 peak amplitude and latency were measured in predetermined channels. P3 peak amplitude at Fz, our main outcome variable, showed excellent reliability in 0back (intraclass correlation coefficient (ICC), 95% confidence interval = 0.82 (0.67-0.90) and 1-back (ICC = 0.87 (0.76-0.93), however, only fair reliability in 2-back (ICC = 0.53 (0.09-0.75). Reliability of P3 peak latencies was substantially lower, with ICCs ranging between 0.17 for 2-back and 0.54 for 0-back. Generalized linear mixed models showed no confounding effect of age, group, or task difficulty on stability of P3 amplitude and latency of Fz. By contrast, MOCA scores tended to negatively correlate with P3 amplitude of Fz (p = 0.07). We conclude that P3 peak amplitude, and to lesser extent P3 peak latency, provide a stable measure of electrophysiological processes in older individuals.

Psychometric Properties of NASA-TLX and Index of Cognitive Activity as Measures of Cognitive Workload in Older Adults

“…These correlation coefficients are slightly higher than those found in our study (ranging between 0.55 and 0.68), which may be because our study focused on older adults with a wide range of cognitive ability. Previous studies have shown a potential confounding effect of cognitive impairment on the reliability of EEG ERP [ 9 , 60 ].…”

“…An extensive description of the 7-min test is provided elsewhere [ 9 ]. In short, each n -back test comprised 180 trials, including 60 (33.3%) target trials and 120 (66.7%) nontarget trials.…”

“…The P3 peak amplitude of the task effect was considered the main outcome measure to test convergent validity against, but we also calculated the P3 peak latency. The P3 peak amplitude and, to a lesser extent, the P3 peak latency are reliable measures of cognitive workload [ 9 ].…”

“…Performance measures such as accuracy and response times are considered indirect measures of cognitive workload expenditure because they do not directly capture brain activity. Accuracy and response times on the n -back test are highly reliable performance measures of working memory in older adults [ 9 ]. The n -back is arguably the most ubiquitous working memory test across the age spectrum [ 10 ], yet previous studies have shown that the n -back test hosts an array of control processes, including speed of processing, storage, comparison processes, updating, keeping track, task mixing, task shifting, and resistance to interference [ 10 , 11 , 12 ].…”

“…The P3 is a positive peak at around 300 ms observed in visual or auditory working memory tasks. This component is considered a sensitive and reliable measure of cognitive workload, including in older adults with cognitive impairment [ 4 , 9 , 34 , 35 , 36 ]. EEG recordings show smaller ERP P3 amplitudes and longer P3 latencies in individuals with AD compared to controls [ 37 , 38 ].…”