# Specificity of functional network connectivity during the AD prodromal phase in mild cognitive impairment

## TL;DR

This study compares brain network connectivity in different types of mild cognitive impairment to understand why one type is more likely to progress to Alzheimer's disease.

## Contribution

The study identifies specific intra- and inter-network functional connectivity differences between aMCI and naMCI that may explain AD progression risk.

## Key findings

- aMCI showed altered intra-network connectivity in the DMN, DAN, SMN, and SN compared to naMCI.
- Inter-network differences were observed in DAN-DMN, DMN-SN, and SN-SMN connections in aMCI.
- These connectivity patterns may help predict which MCI cases are more likely to progress to AD.

## Abstract

Mild cognitive impairment (MCI) is a precursor state of Alzheimer’s disease (AD) and has attracted attention, but why amnestic mild cognitive impairment (aMCI) is more likely to progress to AD than non-amnestic mild cognitive impairment (naMCI) is unclear. The present study of aMCI compares differences in intra- and inter-network functional connectivity (FC) across multiple networks in naMCI and further correlates FC with cognitive assessment scores to assess their ability to predict AD progression.

Resting-state functional magnetic resonance imaging (rs-fMRI) was performed in 30 naMCI and 40 aMCI cases, and 12 resting-state networks (RSNs) were identified by independent component analysis (ICA). Two-sample t-tests were performed to detect intra-network FC differences, and functional network connectivity (FNC) was calculated to compare inter-network FC differences. Subsequently, Pearson or Spearman correlation analyses were used to explore the correlation between altered FC and cognitive assessment scores.

The aMCI compared to the naMCI differed within the (Default mode network) DMN, (Dorsal attention network) DAN, (Sensorimotor system) SMN, and (Salience network) SN networks (corrected for FWEc, P< 0.05), and inter-network differences in DAN-DMN, DMN-SN, SN-SMN (corrected for FWEc, P<0.05).

aMCI contrasts naMCI with widespread intra- and inter-static FNC differences, mainly involving the DMN, DAN, SMN, and SN. these network interactions provide a powerful method for assessing and predicting why aMCI is more likely to progress to AD, and contribute to our understanding of the neurological mechanisms underlying the pathological process of AD.