A passive, neural correlate of verbal fluency in Mild Cognitive Impairment using Fastball neurocognitive assessment

Abstract

AbstractBackgroundFastball provides a passive and objective measure of an individual’s ability to discriminate between different visual categories using Fast Periodic Visual Stimulation and EEG. Our previous work adapted this approach to assess recognition memory in Alzheimer’s disease (Stothart et al., Brain, 2021). This research builds on previous findings by expanding the range of cognitive functions assessed to include visuo‐perceptual performance, and working with patients in an earlier stage of dementia, i.e., Mild Cognitive Impairment (MCI). The aim was to determine whether Fastball responses are sensitive to visuo‐perceptual performance in the early stages of dementia (MCI).MethodAll EEG data were collected in patients' homes using low‐cost, portable systems. Healthy older adult controls (n = 56, ACE‐III = 96 +‐ 6) and MCI patients (n = 50, ACE‐III = 82 +‐ 21) completed a battery of Fastball and neuropsychological tasks (ACE‐III, Freiburg visual acuity) designed to assess visuo‐perceptual performance. We created a letter recognition Fastball task using diffeomorphically scrambled letters as standards and whole letters as oddballs, see Figure 1.ResultA one‐way (Group; Old vs MCI) ANCOVA, controlling for basic steady state magnitude, was conducted to test for differences in oddball responses. Controls had significantly increased oddball responses compared with MCI patients (F (1,103) = 9.61, p = .003, d = 0.48). Oddball responses did not correlate with any neuropsychological measure of vision, but correlated strongly with verbal fluency performance as measured by the ACE‐III, (MCI patients (r(48) = .46, p = .001), controls (r(54) = .34, p = .01)), see Figure 2. There were no correlations between oddball responses and any other neuropsychological measure.ConclusionThese results were not anticipated as we originally hypothesised that oddball responses would correlate with visual performance. Instead, the specific relationship with verbal fluency performance indicates that the Fastball letter recognition task may provide a novel, passive correlate of verbal fluency performance in early dementia. We propose that whole letter oddball stimuli are more salient to participants with greater verbal fluency, resulting in larger oddball responses. A passive measure of verbal fluency could potentially bypass educational and linguistic confounds that can affect traditional measures of verbal fluency performance.