2007-02-20

Future Scent



Lavender essential oil aromatherapy carries a long list of pseudoscience claims, and though some are outrageous, it seems aromatherapy for relaxation may have some science to back it up. Smelling lavender and rosemary increases free radical scavenging activity and decreases cortisol level in saliva, Atsumi and Tonosaki [who are dentists, not psychiatrists], Psychiatry Research, Feb 2007 (epub). "Our study may be the first to report the cortisol-lowering effect of smell in human saliva," they said, concluding that lavender and rosemary scents may provide protection against oxidative stress.

Does this justify my rosemary mint shampoo and lavender soy moisturizer as medical expenses? I wonder what Ben Goldacre would say.

The handful of other aromatherapy studies include Ambient odors of orange and lavender reduce anxiety and improve mood in a dental office, Lehrner et al., Physiol Behav. 2005 Sep 15;86(1-2):92-5, and Aromas of rosemary and lavender essential oils differentially affect cognition and mood in healthy adults, Moss et al., Int J Neurosci. 2003 Jan;113(1):15-38. The latter reported:

... lavender produced a significant decrement in performance of working memory, and impaired reaction times for both memory and attention based tasks compared to controls. In contrast, rosemary produced a significant enhancement of performance for overall quality of memory and secondary memory factors, but also produced an impairment of speed of memory compared to controls. With regard to mood, comparisons of the change in ratings from baseline to post-test revealed that following the completion of the cognitive assessment battery, both the control and lavender groups were significantly less alert than the rosemary condition; however, the control group was significantly less content than both rosemary and lavender conditions. These findings indicate that the olfactory properties of these essential oils can produce objective effects on cognitive performance, as well as subjective effects on mood.


The Reebok Zan Chi Aromatherapy tank top is designed to release lavender or peppermint scent from heat-sensitive fabric but has yet to be studied empirically. Maybe it'd be useful for anxiety-provoking situations beyond yoga, but there's no FDA approval for it or any other of the vast range of aromatherapy products for mental health.

One neuroimaging study, EEG asymmetry responses to lavender and rosemary aromas in adults and infants, Sanders et al., Int J Neurosci, 2002 Nov;112(11):1305-20., recorded a shift from left frontal activity to right frontal (indicating a calmer emotional state), could blossom into a whole new subtype of neuromarketing (neuroperfumery?) for products like Smiley.

Touting itself as an "olfactive antidepressant," Smiley is a perfume containing "micronutrients to activate happiness." Theobromine and phenylethylamine are mixed into extrait de parfum ("maximum dose"), eau de toilette ("normal dose"), and a tanning simulator lotion (dose unspecified). The "pharmacodynamic action" of those neurochemicals is usually delivered via chocolate - ingested - not perfume - an ambient whiff. You could dip yourself in melted chocolate and still not feel elation from phenylethylamine transdermally.

But Smiley doesn't take itself or its scientific claims entirely seriously (being a chic concept from a French parfumier) so at least some consumers won't either. Visual designer ora-ito said, "I was immediately seduced by the idea of taking part in the creation of the very first perfume-treatment! For the Damien Hirst fan that I am, it's a kid's dream coming true to develop an ironic clinical universe." There's a photo of 50 Cents (sic) hyping the brand at Cannes. Ironic is key.

No word from Clinique, manufacturers of Happy.

Makers of lavender and rosemary essential oils must be thrilled by this latest study, but buyer beware. Though hawked by the Discovery Channel, Lovey the Lavender Lamb hasn't been in a lab.





[Cross-posted to Omni Brain]

5 Comments:

Anonymous Roger said...

I think "point of sale" olfactory neuromarketing could be an interesting area of research. Coffee shops, bakeries, etc., have used enticing aromas since their inception. It wouldn't surprise me, though, if seemingly unrelated aromas had an effect on purchasing behavior. Great post!

20/2/07 05:22  
Blogger Sandra said...

Yes, good idea.

20/2/07 18:23  
Blogger Psamathos said...

I am just a little skeptical about some of these papers. Sure, they may show statistically significant effects, but are they relevant? I'm looking at the rosemary and lavender study right now, and here are some of their "significant" findings.

Relevant to controls:
Lavender increased choice reaction time by 40ms.
Rosemary increased spatial memory reaction time by 200ms.
Rosemary increased numerical working memory reaction time by 80ms.
Lavender increased word recognition reaction time by 150ms.

So apparently essential oils "can significantly affect aspects of cognitive performance," but is this effect at all relevant? I like this little bit, which tells you how relevant these results are to actual experience: "In spite of increased subjective alertness ... objective performance [in the rosemary condition] did not improve, which suggests that the enhancements observed for memory may be independent of subjective state." In other words, the effect is too small to notice.

What tells you about the mindset of the people doing this study is that they reference Shakespeare to try to support these findings as "in line with tradition." Completely irrelevant, despite the attractiveness of making that post-hoc connection. Why are they even considering pre-scientific mythologies? Let's stick to the evidence at hand, please.

As a related example, another paper on the efficacy of Ginseng and Ginkgo showed "significant differences" on the order of 0.2 ms for the attentional score, and 40 ms for the memory score. With values this small, it doesn't matter if it's statistically significant, since any effect is completely irrelevant to real performance.

22/2/07 21:23  
Anonymous perfume said...

I think oil factory neuromarketing could be an interesting area of research.

10/5/07 05:58  
Anonymous Anonymous said...

"You could dip yourself in melted chocolate and still not feel elation from phenylethylamine transdermally."

Actually PEA/phenylethylamine is mostly destroyed by the liver when digested. Transdermal is a more effective method of delivery since it bypasses the digestive process.
You do need an effective chemical for transdermal delivery like dmso. alcohol may work to some degree. I imagine the perfume contains alcohol.

15/1/09 01:31  

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