EEG oscillations during word processing predict MCI conversion to Alzheimer's disease

Area of Science:

• Neuroscience
• Cognitive Science
• Neurology

Background:

• Mild cognitive impairment (MCI) is a precursor to dementia, with Alzheimer's disease (AD) characterized by language decline.
• Identifying early biomarkers for AD conversion in MCI patients is crucial for timely intervention.

Purpose of the Study:

• To investigate if electroencephalography (EEG) anomalies during a word comprehension task can predict conversion from MCI to AD.
• To explore differences in brain activity between MCI patients who convert to AD and those who do not, as well as healthy controls.

Main Methods:

• Studied 25 amnestic MCI patients (some converting to AD within 3 years) and 11 elderly controls.
• Utilized a word comprehension task involving auditory category descriptions and visual target words (semantically congruent or incongruent).
• Analyzed EEG activity, focusing on theta (3-5 Hz) and alpha (9-11 Hz) oscillations during word processing and repetition.

Main Results:

• MCI patients converting to AD showed diminished early posterior-parietal theta activity upon initial word presentation compared to non-converters and controls.
• MCI converters displayed distinct oscillatory patterns for processing semantically congruent words, indicating lexical and meaning processing deficits.
• Both MCI groups exhibited abnormal oscillatory signatures for verbal learning/memory of repeated words, with attenuated alpha suppression compared to controls.

Conclusions:

• Subtle breakdowns in language comprehension networks, detectable via EEG, may precede Alzheimer's disease conversion.
• EEG analysis during specific cognitive tasks offers potential as a predictive biomarker for AD progression in MCI patients.
• These findings highlight the role of language processing deficits in the early stages of Alzheimer's disease.