The scent of lavender has long been thought to have calming, antianxiety effects, but the biological mechanism behind this phenomenon has been something of a mystery — until now.
Researchers in Japan [working with mice] found that the vaporized lavender compound linalool triggers a relaxing effect by directly stimulating olfactory sensory neurons.
Clinical use of linalool in human anxiety disorders would require establishing a mechanism for it's anxiolytic effects. The study, published onlineOctober 23 in Frontiers in Behavioral Neuroscience. offers findings toward providing that foundation.
"We confirmed the anxiolytic effects ... in normal mice." ... The effects were "triggered by olfactory input evoked by linalool odor. Absorption to blood flow is not necessary," study investigator Hideki Kashiwadani, PhD, from Kagoshima University, Japan, told Medscape Medical News.
... there was no anxiolytic effect in anosmic mice, whose olfactory neurons had been destroyed. This confirmed that the calming effect seen in normal mice was triggered by [odor chemoreception alone].
...{Notably,] the animals' movements did not become impaired after [smelling] linalool. By contrast, benzodiazepines and linalool injections had effects on movement that were similar to those caused by alcohol.…...
—Lavender's Antianxiety Effects Nothing to Sniff At
by Megan Brooks for MEDSCAPE, October 25, 2018
Prior studies hadn’t addressed the site of action of linalool, assumptions being that inhalation led to bloodstream absorption, in turn to direct effects on gamma-aminobutyric acid A (GABAA) receptors, the same as benzodiazepines do. In normal mice pretreated with flumazenil (which blocks those receptors), linolool evoked no anxiolytic effect and clarified the mechanism’s route.
The study utilized the fact that “...the olfactory system of humans has basically quite similar structure with that of mice." Kashiwadani plans to undertake human studies in the near future, anticipating application for preoperative patients the way that anxiolytic drugs are currently used, to alleviate preoperative stress and facilitate general anesthesia.
Applicability of non-drug anti-anxiety approachs would be particularly beneficial for patients whose age —very, very young or very old— and/or comorbidities pose safety hazards in administration or toleration of conventional drugs.
In light of other recent researchelsewhere finding “Hospitalizations [and] Critical Illness Linked to Dementia-Related Brain Changes”, the increasing public and professional understanding of iatrogenic harmfrom adverse drug effects, and the resultantdeprescribing trends —not opioids alone, but also benzos and z-drugs, other antipsychotics and anti-insomnia meds, preventives of many kinds, and so on—on top of all our anxieties over the current political/governmental climate (and the global climate, and… and… and...), some return to the roots of medicine so we participate more optimally just might be a welcome alternativeto medical business as usual.