Long-lasting effects of lavender exposure on brain resting-state networks in healthy women

TL;DR

Exposure to lavender can change brain activity patterns in healthy women, with effects lasting up to two hours after exposure.

Contribution

This study shows prolonged odor exposure to lavender affects brain networks, with effects persisting after exposure ends.

Findings

Functional connectivity increased in the salience network during lavender exposure.

A negative correlation between the salience and default mode networks emerged after exposure.

Two hours post-exposure, functional connectivity between these networks turned positive.

Abstract

Most brain imaging studies on olfaction focus on short-term odorant stimuli, with few examining long-lasting odor exposure or its after-effects. In this study, we utilized resting-state fMRI (rsfMRI) to investigate the effects of prolonged odor exposure to lavender on brain activity and whether these persist post-exposure.

Fourteen healthy women underwent two fMRI sessions, conducted one week apart, in a randomized order. Both sessions included rsfMRI scans before, during, and up to 2 h after a 14 min exposure to either lavender essential oil or a non-odorant control.

An Independent Component Analysis identified the salience network (SAL) and default mode network (DMN) as the most consistent resting-state networks. A two-factorial ANOVA revealed significant time-varying interaction effects between the SAL and DMN. During odor exposure, functional connectivity (FC) increased within the SAL, and a negative correlation between the SAL and DMN appeared, which intensified immediately after exposure. Two hours post-exposure, the FC between SAL and DMN turned positive.

These findings suggest that prolonged odorant exposure to lavender can induce long-lasting brain effects detectable up to 2 h afterwards in women. This proof-of-concept study should be extended to other odorants and to men, and offers new possibilities for exploring the effects of aromatherapy or other odor exposure interventions on brain activity.

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