Altered resting state networks in mild cognitive impairment and mild Alzheimer's disease: an fMRI study

Area of Science:

• Neuroscience
• Medical Imaging
• Cognitive Science

Background:

• The default mode network (DMN) is crucial for cognitive functions.
• Understanding DMN activity changes is vital for early detection of neurodegenerative diseases like Alzheimer's disease (AD).
• Mild cognitive impairment (MCI) represents a potential transitional stage between healthy aging and dementia.

Purpose of the Study:

• To investigate the activity and reactivity of the DMN in individuals with MCI, mild AD, and healthy elderly controls (HC).
• To determine if DMN alterations can serve as an early diagnostic marker for AD pathology.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed to measure brain activity.
• The study involved 28 individuals with MCI, 18 patients with mild AD, and 41 HC.
• DMN activity was assessed through deactivations during visual encoding and nonspatial working memory tasks.

Main Results:

• DMN deactivation was observed in the anterior frontal cortex, precuneus, and posterior cingulate cortex.
• MCI patients exhibited less DMN deactivation than HC but more than AD patients.
• The early phase of DMN deactivation, particularly in the anterior frontal cortex, significantly differentiated MCI from HC and AD.

Conclusions:

• Altered DMN activity, especially in the anterior frontal cortex and precuneus, may serve as an early indicator of AD.
• Findings support the view of MCI as a transitional state and highlight early DMN changes in MCI.
• DMN reactivity patterns offer potential for distinguishing between healthy aging, MCI, and early AD.