# Altered Prefrontal Dynamic Functional Connectivity in Vascular Dementia During Olfactory Stimulation: An fNIRS Study

## TL;DR

This study uses fNIRS to show that vascular dementia patients have more variable brain connectivity during smell tests compared to healthy people.

## Contribution

The study introduces olfactory-evoked dynamic functional connectivity as a potential non-invasive tool for understanding vascular dementia.

## Key findings

- VD patients showed more extensive dFC fluctuations during olfactory stimulation.
- Differences in dFC were observed in oxy- and deoxyhemoglobin signals across multiple brain regions.
- Effect sizes between groups were moderate to large during olfactory stimulation.

## Abstract

In this study, we employed functional near-infrared spectroscopy (fNIRS) to explore dynamic functional connectivity (dFC) responses to olfactory stimulation in thirteen healthy control participants and seven patients with vascular dementia (VD). Participants underwent five rest and odor exposure cycles, and dFC was estimated using a sliding window correlation approach. The healthy control group exhibited limited changes, while the VD group exhibited more extensive fluctuations in both oxy- and deoxyhemoglobin dFC across multiple regions during several stimulation periods. Between-group analyses revealed differences, particularly during olfactory stimulation, with moderate to large effect sizes. These preliminary findings suggest that olfactory-evoked dFC may reflect altered brain network dynamics in VD and could potentially serve as a non-invasive, accessible tool to help understand vascular dementia.