EEG markers for cognitive decline in elderly subjects with subjective memory complaints

Area of Science:

• Neuroscience
• Cognitive Science
• Biophysics

Background:

• Early detection of cognitive decline is crucial for Alzheimer's disease (AD) treatment.
• Existing studies often use a limited set of measures for identifying early decline.
• Subjective memory complaints (SMC) may indicate early neuropsychological decline.

Purpose of the Study:

• To identify the profile of brain function measures that best define early neuropsychological decline.
• To compare electroencephalography (EEG) measures between individuals with SMC and controls.
• To relate identified EEG markers to cognitive performance.

Main Methods:

• Compared subjects with SMC to normative controls using a wide range of EEG measures.
• Included novel measures like event-related spatio-temporal waves and biophysical modeling.
• Assessed cognitive performance on learning and executive function tasks.

Main Results:

• Individuals with SMC showed elevated alpha power and increased spatio-temporal wave events.
• Higher alpha power and altered wave activity correlated with declines in verbal memory, maze performance, and working memory reaction time.
• Biophysical modeling suggested decreased cortical/thalamic inhibitory gains and slowed dendritic time-constants in SMC subjects.

Conclusions:

• A distinct electrophysiological profile characterizes early cognitive decline in individuals with SMC.
• These changes suggest nonlinear progression in electrophysiological alterations from early decline to dementia.
• Electrophysiological changes in SMC can have varied relationships with memory-related task performance.