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Background <p>With increasing life expectancy, age-related cognitive disorders including mild cognitive impairment (MCI) represent major public health challenges, and amnestic MCI (aMCI) has the greatest risk of progression to dementia due to Alzheimer’s disease (AD). Event-related potentials (ERPs), particularly the P200 component, have been studied as potential biomarkers, but conventional grand-averaged approaches often yield inconsistent results. This study examined the temporal dynamics of prefrontal ERPs in a large cohort of older adults to assess neural adaptation processes associated with early cognitive decline.</p> Method <p>The participants included 636 older adults from the Gwangju Alzheimer’s and Related Dementia cohort. Two-channel prefrontal ERPs were recorded using a portable EEG system during an auditory oddball task, focusing on standard stimuli. Temporal dynamics based on the time-averaged P200 amplitude (TAP2A) were evaluated using time–trial plots, temporal segmentation into 18 epoch bins, repeated-measures ANOVAs, effect size estimation, individual slope regression and group comparisons.</p> Results <p>Time–trial plots revealed blurred and attenuated P200 responses in aMCI patients, whereas the responses of cognitively normal (CN) participants remained relatively stable. Although the time × group interaction was not significant, a significant main effect of time was primarily driven by aMCI. Post hoc pairwise comparisons revealed significant decreases in TAP2A beginning at the 12th epoch, with a medium-to-large effect size (partial η² = 0.101). Group-level slopes of -0.0027, -0.0047, and − 0.0033 were derived from individual coefficients for the CN, aMCI, and nonamnestic MCI (naMCI) groups. The linear model provided a better fit for the aMCI group (R<sup>2</sup> = 0.796) than for the CN (R<sup>2</sup> = 0.375) and naMCI (R<sup>2</sup> = 0.547) groups, suggesting accelerated trial-by-trial decline. The group comparison revealed significant differences between the CN and aMCI groups in later time bins (epochs 12–18, <i>p</i> &lt; 0.01).</p> Discussion <p>aMCI was associated with accelerated neural adaptation, reflected by trial-by-trial reductions in TAP2A that may indicate altered attentional allocation and reduced neural efficiency. Compared with static measures, temporal dynamics appeared more sensitive to group-related differences among aMCI, CN, and naMCI participants. These findings suggest that slope-based temporal indices may hold exploratory potential as noninvasive indicators of memory-related cognitive change, complementing neuropsychological assessments and contributing to the early characterization of individuals who may be at increased risk of developing AD.</p>

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Altered temporal dynamics of prefrontal ERP responses reflecting neural adaptation in patients with amnestic mild cognitive impairment

  • 期刊论文

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  • 发表日期：

    2026年1月7日

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  • Jang-Han Bae,
  • Minho Choi,
  • Kun Ho Lee,
  • Jaeuk U. Kim

摘要

Background

With increasing life expectancy, age-related cognitive disorders including mild cognitive impairment (MCI) represent major public health challenges, and amnestic MCI (aMCI) has the greatest risk of progression to dementia due to Alzheimer’s disease (AD). Event-related potentials (ERPs), particularly the P200 component, have been studied as potential biomarkers, but conventional grand-averaged approaches often yield inconsistent results. This study examined the temporal dynamics of prefrontal ERPs in a large cohort of older adults to assess neural adaptation processes associated with early cognitive decline.

Method

The participants included 636 older adults from the Gwangju Alzheimer’s and Related Dementia cohort. Two-channel prefrontal ERPs were recorded using a portable EEG system during an auditory oddball task, focusing on standard stimuli. Temporal dynamics based on the time-averaged P200 amplitude (TAP2A) were evaluated using time–trial plots, temporal segmentation into 18 epoch bins, repeated-measures ANOVAs, effect size estimation, individual slope regression and group comparisons.

Results

Time–trial plots revealed blurred and attenuated P200 responses in aMCI patients, whereas the responses of cognitively normal (CN) participants remained relatively stable. Although the time × group interaction was not significant, a significant main effect of time was primarily driven by aMCI. Post hoc pairwise comparisons revealed significant decreases in TAP2A beginning at the 12th epoch, with a medium-to-large effect size (partial η² = 0.101). Group-level slopes of -0.0027, -0.0047, and − 0.0033 were derived from individual coefficients for the CN, aMCI, and nonamnestic MCI (naMCI) groups. The linear model provided a better fit for the aMCI group (R2 = 0.796) than for the CN (R2 = 0.375) and naMCI (R2 = 0.547) groups, suggesting accelerated trial-by-trial decline. The group comparison revealed significant differences between the CN and aMCI groups in later time bins (epochs 12–18, p < 0.01).

Discussion

aMCI was associated with accelerated neural adaptation, reflected by trial-by-trial reductions in TAP2A that may indicate altered attentional allocation and reduced neural efficiency. Compared with static measures, temporal dynamics appeared more sensitive to group-related differences among aMCI, CN, and naMCI participants. These findings suggest that slope-based temporal indices may hold exploratory potential as noninvasive indicators of memory-related cognitive change, complementing neuropsychological assessments and contributing to the early characterization of individuals who may be at increased risk of developing AD.