Alpha desynchronization during simple working memory unmasks pathological aging in cognitively healthy individuals

Area of Science:

• Neuroscience
• Biomarkers
• Cognitive Science

Background:

• Early detection of Alzheimer's disease (AD) is crucial for intervention.
• Cognitive challenge combined with objective physiological measures may reveal subtle neurological changes.
• Frontal alpha event-related desynchronization (ERD) is a potential indicator of brain activity.

Purpose of the Study:

• To investigate if cognitive challenge and objective physiology can identify abnormal frontal alpha ERD in early Alzheimer's disease (AD).
• To differentiate between cognitively healthy individuals with normal (CH-NAT) versus pathological (CH-PAT) amyloid/tau ratios using quantitative electroencephalography (qEEG).

Main Methods:

• Utilized qEEG to analyze brain activity during N-back working memory (WM) tasks (N=0 and N=2) in aging participants.
• Assessed alpha power and alpha spectral entropy (SE) at rest and during ERD (250-750 ms).
• Compared qEEG measures between CH-NAT (n=10) and CH-PAT (n=14) subgroups (ages 60-100).

Main Results:

• During 0-back WM, behavioral performance was similar between groups.
• qEEG differentiated groups: CH-PAT showed decreased alpha ERD across all regions, unlike CH-NAT (parietal region only).
• Alpha SE increased in frontal/left lateral regions for CH-PAT and was higher frontally compared to CH-NAT (p<0.01).

Conclusions:

• Alpha ERD and SE analyses indicate frontal lobe dysfunction during WM processing in the CH-PAT stage.
• These qEEG measures show potential as early biomarkers for Alzheimer's disease.
• Further research is needed to establish the clinical significance of these findings.