# Exploring the pathogenic mechanisms of dementia risk factors: a task-fMRI study of mild cognitive impairment

## TL;DR

This study uses fMRI to explore how dementia risk factors affect brain activity in mild cognitive impairment patients, focusing on the default mode network.

## Contribution

The study identifies a novel link between dementia risk factors and increased default mode network activity during memory retrieval.

## Key findings

- Higher risk factor scores correlate with worse cognitive performance across multiple tests.
- Increased risk factor scores are associated with heightened brain activity in the default mode network during retrieval.
- Elevated default mode network activity may contribute to amyloid-β accumulation, a hallmark of Alzheimer's disease.

## Abstract

To investigate the mechanism by which risk factors influence brain functioning using task-based functional magnetic resonance imaging (fMRI), providing a theoretical basis for controlling these risk factors.

Risk factors associated with MCI-to-AD conversion were collected from 31 amnestic mild cognitive impairment (aMCI) patients and scored according to the Cardiovascular Risk Factors, Aging, and Dementia (CAIDE) dementia risk scale. The relationships between risk scores, cognitive function, and task-based fMRI brain activity were analyzed.

Risk factor score was negatively correlated with multiple cognitive performances, including the Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Auditory Verbal Learning Test (AVLT) immediate recall and delayed recall, digit span forward and backward, and Boston Naming Test (BNT). Task-based fMRI whole-brain and region-of-interest (ROI) analyses revealed a positive correlation between risk factor score and brain activity in default mode network (DMN) during the retrieval phase.

Risk factors can abnormally increase brain activity in DMN. Given the close association between amyloid-β (Aβ) deposition and reduced DMN deactivation, these risk factors may elevate DMN activity, thereby facilitate Aβ accumulation in these regions.