Longitudinal Changes in Functional Brain Connectivity Predicts Conversion to Alzheimer's Disease.

Area of Science:

• Neuroscience
• Medical Imaging
• Neurology

Background:

• Alzheimer's disease (AD) diagnosis often occurs late, necessitating early biomarkers.
• Mild cognitive impairment (MCI) is a prodromal stage for AD, offering a window for early detection.
• Understanding structural and functional brain changes in MCI is crucial for predicting AD progression.

Purpose of the Study:

• To identify prognostic biomarkers for Alzheimer's disease (AD) conversion in patients with amnestic mild cognitive impairment (MCI).
• To longitudinally investigate structural and functional brain modifications over two years in pre-dementia stages.
• To compare brain changes between MCI patients who convert to AD and those who do not.

Main Methods:

• Longitudinal study of 31 patients with amnestic MCI over a 2-year follow-up.
• Clinical, neuropsychological, and magnetic resonance imaging (MRI) assessments.
• Retrospective classification of patients into AD Converters and Non-Converters for comparative analysis.

Main Results:

• Baseline MRI revealed greater grey matter atrophy and default-mode network (DMN) disconnection in Converters.
• Longitudinal analysis showed accelerated frontotemporal grey matter atrophy and increased precuneus connectivity in Converters.
• Discriminant analysis identified precuneus DMN functional connectivity as a highly accurate predictor of AD conversion.

Conclusions:

• Baseline functional connectivity of the precuneus within the DMN is a sensitive and specific biomarker for predicting AD conversion in MCI patients.
• Early structural and functional brain alterations in MCI can predict future progression to Alzheimer's disease.
• This finding supports the potential of DMN connectivity as an early diagnostic and prognostic tool for Alzheimer's disease.