Structural and functional patterns in healthy aging, mild cognitive impairment, and Alzheimer disease

Area of Science:

• Neuroimaging
• Neurology
• Biomedical Engineering

Background:

• Mild cognitive impairment (MCI) is a transitional stage between normal aging and Alzheimer disease (AD).
• Accurate diagnosis of MCI and AD is crucial for timely intervention and management.
• Current diagnostic methods have limitations in early and precise detection.

Purpose of the Study:

• To evaluate the combined diagnostic utility of magnetic resonance imaging (MRI) and magnetoencephalography (MEG) for Alzheimer disease (AD) and mild cognitive impairment (MCI).
• To assess the individual and combined contributions of volumetric MRI and MEG in differentiating AD, MCI, and control groups.

Main Methods:

• Whole-head magnetoencephalography (MEG) recordings were acquired from participants diagnosed with AD, MCI, and controls.
• Volumetric magnetic resonance imaging (MRI) data, including global brain, temporal lobe, and hippocampal volumes, were obtained.
• Classification algorithms were applied to MRI and MEG data, both individually and in combination.

Main Results:

• Reduced hippocampal volume differentiated AD and MCI patients from controls, achieving 91.3% (AD vs. Control) and 83.3% (MCI vs. Control) correct classification.
• MEG revealed significantly higher theta and delta activity in AD patients compared to MCI and controls, particularly in parietal, temporal, and occipital regions.
• Individual MEG measures showed varying classification rates (e.g., Left parietal theta: 78.3% for Controls vs. MCIs).

Conclusions:

• Hippocampal volume reduction is a key MRI indicator for distinguishing AD and MCI from controls.
• MEG-detected alterations in brain activity (theta and delta waves) are characteristic of AD.
• The integration of MRI and MEG significantly enhances diagnostic accuracy for MCI and AD, underscoring the value of multimodal neuroimaging approaches.