Interindividual and intraindividual variability in amnestic mild cognitive impairment (aMCI) measured with an online cognitive assessment

Abstract

Introduction: Mean cognitive performance is worse in amnestic mild cognitive impairment (aMCI) compared to control groups. However, studies on variability of cognitive performance in aMCI have yielded inconclusive results, with many differences in variability measures and samples from one study to another.Methods: We examined variability in aMCI using an existing older adult sample (n=91; 51 with aMCI, 40 with normal cognition for age), measured with an online self-administered computerized cognitive assessment (Cogniciti's Brain Health Assessment). Our methodology extended past findings by using pure measures of variability (controlling for confounding effects of group performance or practice), and a clinically representative aMCI sample (reflecting the continuum of cognitive performance between normal cognition and aMCI).Results: Between-group t-tests showed significantly greater between-person variability (interindividual variability or diversity) in overall cognitive performance in aMCI than controls, with a small to moderate effect size, d = 0.44. No significant group differences were found in within-person variability (intraindividual variability) across cognitive tasks (dispersion) or across trials of a response time task (inconsistency), which may be because we used a sample measuring the continuum of cognitive performance. Exploratory correlation analyses showed that a worse overall score was associated with greater inter-and intraindividual variability, and that variability measures were correlated with each other, indicating people with worse cognitive performance were more variable.Discussion: The current study demonstrates that self-administered online tests can be used to remotely assess different types of variability in people at risk of Alzheimer`s. Our findings show small but significantly more interindividual differences in people with aMCI. This diversity is considered as 'noise' in standard assessments of mean performance, but offers an interesting and cognitively informative 'signal' in itself.

Variability across subjects in free recall versus cued recall

“…We have presented evidence that individuals vary more from one another on cued recall tasks than on free recall tasks. Examinations of differences in inter-individual variability have proven fruitful in other domains (e.g., Christensen et al, 1999, LaPlume et al, 2021Yao et al,…”

“…Examinations of variability in cognitive performance (both within-and acrossparticipants) have been applied fruitfully in other domains such as cognitive ageing, where researchers have found increasing variability with age and evidence of links between intraindividual variability and developmental outcomes (e.g., Christensen et al, 1999, LaPlume et al, 2021Yao et al, 2016). However, we are not aware of research directly comparing variability in performance on standard FR and CR tests.…”

Evidence-based yet still challenging! Research on physical activity in old age

“…Compared to other age groups, old age is typified by increased heterogeneity, which complicates research [14] and renders practice harder to conduct [15]. This heterogeneity is typical of physical performance (e.g., [16]), as well as cognitive (e.g., [17]) and behavioral (e.g., [18]) performance.…”