Evolution of global and local grey matter atrophy on serial MRI scans during the progression from MCI to AD

Area of Science:

• Neuroimaging
• Neurodegeneration
• Cognitive Neurology

Background:

• Mild cognitive impairment (MCI) is a prodromal stage for dementia, particularly Alzheimer's disease (AD).
• Understanding the neuroanatomical differences between progressive and stable MCI is crucial for early detection and intervention.
• Grey matter (GM) changes precede clinical diagnosis in neurodegenerative diseases.

Purpose of the Study:

• To characterize grey matter (GM) distribution and dynamics in progressive versus stable MCI over a two-year period before Alzheimer's disease (AD) conversion.
• To identify specific brain regions affected by GM loss in individuals who progress from MCI to AD.

Main Methods:

• Longitudinal voxel-based morphometry (VBM) analysis of three serial MRI scans.
• Inclusion of 48 stable MCI and 12 progressive MCI cases.
• Scans acquired at approximately 1-year intervals, with the final scan for the progressive group at AD diagnosis.

Main Results:

• Cross-sectional analysis revealed lower GM volumes in the parahippocampal gyrus, precuneus, and posterior cingulate 12 months before AD diagnosis in the progressive MCI group.
• Longitudinal VBM showed accelerated GM loss in temporal neocortex, parahippocampal cortex, and cingulate gyrus in progressive MCI.
• Affected regions also included the frontal lobe, insula, and cerebellum in the progressive MCI group.

Conclusions:

• Progressive MCI exhibits significant grey matter atrophy in specific cortical and subcortical regions preceding clinical Alzheimer's disease diagnosis.
• These findings offer insights into the neurodegenerative processes underlying MCI progression to AD.
• Further studies are needed to verify the clinical relevance of these observed neuroanatomical changes.