Resting-state brain waves may help explain how the molecular hallmarks of Alzheimer’s disease translate into memory problems, according to a study published in Alzheimer’s Research & Therapy. Researchers report that reduced beta-band oscillatory activity, measured with a simple non-invasive electroencephalogram (EEG), appears to act as a bridge between amyloid-β pathology and impaired memory, while tau pathology shows a more direct relationship with cognitive decline.

The study compared 36 participants with biomarker-confirmed, amyloid-positive Alzheimer’s disease-related mild cognitive impairment (AD-MCI) against 38 cognitively normal older adults. All participants underwent resting-state EEG recordings, in which brain activity is measured while a person sits quietly without performing a task. The patients with AD-MCI additionally received positron emission tomography (PET) scans to quantify their amyloid-β and tau burdens, the two protein pathologies that define Alzheimer’s disease.

The researchers analyzed power spectral density across EEG frequency bands and found a clear pattern of group differences. This spectral shift suggests that even at rest, the brains of people in the early symptomatic stage of Alzheimer’s disease oscillate differently from those of healthy older adults.

Correlating the EEG measures with PET biomarkers revealed distinct roles for the two proteins. Greater amyloid burden was associated with lower beta-band activity across multiple brain regions. Higher tau burden was associated with reduced beta activity as well, but tau was also linked to regionally increased delta and theta activity. In other words, both pathologies related to beta-band suppression, while the slowing of brain rhythms appeared more specifically tied to tau.

Cognition was assessed with the Cognitive Abilities Screening Instrument (CASI). Poorer memory performance was associated with reduced beta activity and increased theta activity, tying the same oscillatory markers to measurable cognitive deficits. Notably, the two pathologies diverged in how they related to memory. Amyloid burden showed no robust direct association with memory performance once the data were examined closely, but it was indirectly associated with memory through beta-band activity. Tau burden, by contrast, was directly associated with poorer memory, and no significant mediation effects through beta activity were observed for tau.

To test these pathways formally, the team used regression-based mediation analyses with adjustment for age, sex, education, and APOE ε4 status, key demographic and genetic factors that could otherwise confound the results.

The authors conclude that beta-band activity may represent a systems-level correlate linking Alzheimer’s pathology and cognition.

Several limitations should be kept in mind. The study was cross-sectional, so it captures associations at a single point in time and cannot establish causal sequences or long-term trajectories. The sample sizes were modest, with 36 patients and 38 controls, and the cohort consisted of older adults at the mild cognitive impairment stage rather than the full Alzheimer’s disease continuum. The article was published as an accepted-manuscript version shared early for faster access, subject to further edits before the final Version of Record. Mediation analysis identifies statistical pathways rather than proven mechanisms, and the cross-sectional design and modest sample sizes mean the findings describe associations at a single point in time.

Subject of Research: Resting-state EEG beta-band activity as a link between amyloid and tau pathology and memory impairment in Alzheimer's disease

Article Title: Resting-state beta-band oscillatory dysfunction bridges Alzheimer’s pathology and memory impairment

Article References: Cheng, C.-H., Lu, H., Chang, H.-I., Huang, S.-H., Lin, T.-Y., Hsueh, C.-Y., & Chang, C.-C. (2026). Resting-state beta-band oscillatory dysfunction bridges Alzheimer’s pathology and memory impairment. Alzheimer's Research & Therapy. https://doi.org/10.1186/s13195-026-02234-x

Image Credits: AI Generated

DOI: 10.1186/s13195-026-02234-x

Keywords: Alzheimer's disease, resting-state EEG, beta-band oscillations, amyloid-beta, tau PET, mild cognitive impairment, memory, biomarkers, mediation analysis, power spectral density, CASI, APOE ε4