Differences in structural and functional default mode network connectivity in amyloid positive mild cognitive...

Area of Science:

• Neuroscience
• Biomarkers
• Alzheimer's Disease Research

Background:

• The default mode network (DMN) is a potential Alzheimer's disease (AD) biomarker.
• It remains unclear if DMN can predict conversion from amnestic mild cognitive impairment with altered amyloid (aMCI-Aβ+) to AD.
• Investigating structural and functional connectivity, hippocampal volumes, and CSF biomarkers is crucial.

Purpose of the Study:

• To determine if DMN structural and functional connectivity, hippocampal volumes, and CSF biomarkers can differentiate aMCI-Aβ+ converters from non-converters.
• To assess the predictive value of these markers for AD progression in aMCI-Aβ+ individuals.

Main Methods:

• Followed 48 individuals (18 controls, 30 aMCI-Aβ+) for 13 months.
• Utilized diffusion tensor imaging, functional connectivity (FC) analysis, hippocampal volume (HV) measurement, and CSF biomarker assays (Aβ42, p-Tau, t-Tau).
• Employed MANOVAs and univariate analyses for group comparisons.

Main Results:

• 26.6% of aMCI-Aβ+ individuals converted to AD dementia.
• No significant differences were found in CSF biomarkers or DMN functional connectivity between converters and non-converters.
• aMCI-Aβ+ converters exhibited smaller right hippocampal volumes and greater radial diffusivity in the right cingulum parahippocampal bundle compared to controls and/or non-converters.

Conclusions:

• Structural DMN alterations, specifically in the right hippocampus and cingulum parahippocampal bundle, may differentiate aMCI-Aβ+ individuals who convert to AD dementia.
• Functional DMN connectivity did not show significant differences between converters and non-converters in this study.
• These findings suggest structural DMN changes are more promising biomarkers for predicting AD conversion in aMCI-Aβ+ individuals.