Ancient Greeks held essential oils in the highest esteem, believing that rosemary oil in particular could improve memory. In the 15th century, rosemary was believed to be a disinfectant. The documented clinical use of essential oils for mood-disorders goes back to 1920s Europe. Throughout the centuries, people have reported the same effects for the same oils.
In the last decade, researchers who hadn’t often officially studied essential oils, wanted to know – Is this just a belief? Or do these claimed far-reaching complex oils produce an actual biological shift?
In a controlled blind study in 2003, published in International Journal of Neuroscience, researchers not only confirmed one wide belief about rosemary oil, but unwittingly showed the importance of knowing the recommended uses of oils like lavender.
M. Moss et al wanted to evaluate the olfactory impact of the essential oils (EOs) of lavender (Lavandula angustifolia) and rosemary (rosemarinus officinalis) on cognitive performance and mood in healthy volunteers.
One hundred and forty-four participants believed they were merely taking a Cognitive Drug Research (CDR) computerized cognitive assessment battery test. Each individual was randomly placed in one of three cubicles with doors: one containing rosemary EO aroma, one containing lavender EO aroma, and the other, none (control).
Before exposure to the aroma (or none) they completed visual analogue mood questionnaires, and subsequently after completion of the test battery. The participants were deceived as to the genuine aim of the study until the completion of testing to prevent expectancy effects from possibly influencing the data. The CDR was testing their cognition and memory with or without exposure to the EO.
Notably, lavender actually showed a significant decline in performance of working memory and delayed reaction times for memory and attention based tasks compared to controls. (It’s usually used for anxiety)
Rosemary, in contrast, significantly enhanced performance for overall memory quality and secondary memory factors, but the researchers thought it impaired the speed of memory compared to controls. Better memory, less speed execution of memory.
As for the mood factor – while both the control and lavender groups were less alert than the rosemary group – both lavender and rosemary groups were found to be more content than the control group.
One psychiatry critique (against rosemary?) thought that the results of this study were mixed at best, although this study continues to be cited in not only other EO studies, but cognitive and mental health ones as well. Interestingly, the critique mentioned another study showing that instead of rosemary decreasing anxiety – it might actually increase it during an anxiety attack. (It makes sense when you consider the keen alert factor of rosemary)
By sorting through belief and fact, researchers are confirming age old beliefs about the health benefits of EOs, but also proving the importance of knowing the EOs’ intended purpose. Knowing that difference can improve your well-being and prevent unintended results.
In conclusion, M. Moss et al write:
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.
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