Differential medial temporal lobe and default-mode network functional connectivity and morphometric changes in...

Area of Science:

• Neuroimaging
• Neurology
• Alzheimer's Disease Research

Background:

• Alzheimer's Disease (AD) is characterized by progressive neurodegeneration.
• Early detection of AD biomarkers is crucial for timely intervention.
• Distinguishing early mild cognitive impairment (MCI) from cognitively normal states is challenging.

Purpose of the Study:

• To investigate medial temporal lobe resting-state functional connectivity (rsFC) and morphometric changes in the transition from cognitively normal to early MCI.
• To identify early AD biomarkers that may precede clinical diagnosis.

Main Methods:

• Utilized a dataset of 105 subjects from the Alzheimer's Disease Neuroimaging Initiative (ADNI).
• Employed FreeSurfer for morphometric analysis (atrophy, cortical thinning).
• Analyzed rsFC in the medial temporal lobe and default-mode network (DMN) regions.

Main Results:

• Morphometric changes (atrophy, thinning) were evident in mild AD but not early MCI.
• rsFC disruptions were detected earlier, in early MCI, affecting medial temporal lobe and DMN regions.
• Specific findings include focal rsFC organization, hyperconnectivity in ventral MTL, and hypoconnectivity between dorsal MTL and DMN nodes.

Conclusions:

• Medial temporal lobe rsFC is a sensitive indicator of early AD neuropathology.
• rsFC changes may serve as an early biomarker, potentially preceding clinical and even some structural changes.
• These findings highlight rsFC's role in the AD pathophysiological cascade.