High-frequency EEG activity moderates the association between amyloid burden and tau in cognitively normal adults
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Background
Resting electroencephalogram (EEG) may capture early excitatory-inhibitory (E-I) imbalance in Alzheimer’s disease, but its relationship to beta-amyloid (Aβ) and tau in cognitively normal adults is unclear.
Methods
We analyzed resting-state EEG from 24 older adults: 21 cognitively normal (13 Aβ-negative, 8 Aβ-positive) and 3 with MCI/AD (all Aβ-positive), with Aβ positron emission tomography (PET); 20 cognitively normal adults also had tau PET. Four parietal EEG measures reflecting excitation-inhibition (E-I) balance and neuronal excitability (periodic gamma power, alpha-gamma and theta-gamma phase-amplitude coupling [PAC], and the aperiodic exponent) were assessed for associations with Aβ burden and early medial temporal lobe (MTL) tau, adjusting for age and sex.
Results
In 21 cognitively normal adults, higher Aβ burden was associated with higher parietal periodic gamma power (β = +0.50, p = 0.025). No E-I measure was associated with MTL tau across all participants. However, in Aβ-positive adults, higher periodic gamma was associated with higher MTL tau, most strongly in the entorhinal cortex (ρ = +0.90, p = 0.002), with no association in Aβ-negative adults. Importantly, periodic gamma also moderated the association between Aβ and MTL tau (p = 0.012; consistent across MTL regions after FDR correction).
Conclusions
In this pilot study, parietal periodic gamma, an EEG marker of cortical excitability, increased with Aβ burden and was related to MTL tau only in the presence of Aβ. Periodic gamma power may serve as a candidate marker of Aβ-associated E-I imbalance and early AD progression.
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High-frequency EEG activity moderates the association between amyloid burden and tau in cognitively normal adults #NeuroDegeneration 🧪🧠 https://www.medrxiv.org/content/10.64898/2026.10.30.26366850v1
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